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Окислительный стресс и глутатион в растениях

Журнальные статьи

Ahmad M.S.A., Ashraf M. Essential Roles and Hazardous Effects of Nickel in Plants // Reviews of Environmental Contamination and Toxicology, Vol 214 / ed. Whitacre D.M. 2011. Vol. 214. P. 125–167.

Nickel is one of 23 metal pollutants of great concern to the environment and to human health (Sunderman 1992; Jarup 2003; Duda-Chodak and Baszczyk 2008). Nickel is the 24th most abundant element (twice as Cu) and comprises approximately 0.008% of the content of the earth’s crust; hence, it is a natural component of soil (parent material) and water (Alloway 1995; Hostynek and Maibach 2002; Hedfi et al. 2007). Most of the earth’s nickel, however, is inaccessible, as it is locked in the iron–nickel molten core, which constitutes approximately 10% nickel. The second largest Ni deposits of the earth rest in the sea. It is estimated that the sea contains approximately eight billion tons of Ni, either dissolved in seawater or deposited in the seabed (Birch 1964; Stixrude et al. 1997). Soils may contain nickel levels as low as 0.2 mg kg?1 or as high as 450 mg kg?1. The average nickel content in soil is approximately 20 mg kg?1; however, the content level may vary greatly depending upon the mode of origin of the soil’s parent material (Assembly of Life Sciences 1975; Aubert and Pinta 1978; Wilson and Kordybach 2000). Because organic matter strongly absorbs some metals, particularly nickel, fossil fuels such as coal and oil may contain considerable amounts of nickel (Sigel et al. 2005). Moreover, Ni naturally occurs in a few plants (legumes) where it functions as an essential component of some enzymes (e.g., ureases) that are involved in nitrogen assimilation (Eskew et al. 1984; Brown et al. 1987a; Sakamoto and Bryant 2001).

Anjum N.A. et al. Metal/metalloid stress tolerance in plants: role of ascorbate, its redox couple, and associated enzymes // Protoplasma. 2014. Vol. 251, № 6. P. 1265–1283.

The enhanced generation of reactive oxygen species (ROS) under metal/metalloid stress is most common in plants, and the elevated ROS must be successfully metabolized in order to maintain plant growth, development, and productivity. Ascorbate (AsA) is a highly abundant metabolite and a water-soluble antioxidant, which besides positively influencing various aspects in plants acts also as an enigmatic component of plant defense armory. As a significant component of the ascorbate-glutathione (AsA-GSH) pathway, it performs multiple vital functions in plants including growth and development by either directly or indirectly metabolizing ROS and its products. Enzymes such as monodehydroascorbate reductase (MDHAR, EC and dehydroascorbate reductase (DHAR, EC maintain the reduced form of AsA pool besides metabolically controlling the ratio of AsA with its oxidized form (dehydroascorbate, DHA). Ascorbate peroxidase (APX, EC utilizes the reduced AsA pool as the specific electron donor during ROS metabolism. Thus, AsA, its redox couple (AsA/DHA), and related enzymes (MDHAR, DHAR, and APX) cumulatively form an AsA redox system to efficiently protect plants particularly against potential anomalies caused by ROS and its products. Here we present a critical assessment of the recent research reports available on metal/metalloid-accrued modulation of reduced AsA pool, AsA/DHA redox couple and AsA-related major enzymes, and the cumulative significance of these antioxidant system components in plant metal/metalloid stress tolerance.

Anjum N.A. et al. Modulation of glutathione and its related enzymes in plants’ responses to toxic metals and metalloids-A review // Environmental and Experimental Botany. 2012. Vol. 75. P. 307–324.

The rapid increase in the contamination of the environment by toxic metals (TMs) and metalloids is posing serious threats to biotic communities. Plants are among the organisms most vulnerable to TMs and metalloids due to their sedentary and stationary existence under changing environmental conditions. Toxic metals- and metalloids-stress-impacts cause either directly or indirectly excessive generation of reactive oxygen species (ROS) leading to oxidative stress in plants. Being a significant component of ascorbate-glutathione (AsA-GSH) pathway, tripeptide glutathione (GSH, ?-Glu-Cys-Gly) is involved in both direct and indirect control of ROS and their reaction products concentrations in cells and thus, protects plants against TMs- and metalloids-mediated oxidative stress. Additionally, several GSH-related enzymes such as GSH reductase (GR, EC, GSH peroxidases (GPXs, EC and GSH sulfo-transferases (GSTs, EC cumulatively form an efficient defense system to protect plants against ROS-induced effects in addition to their significance for the detoxification, chelation and compartmentalization of major TMs and metalloids in plants. The present review critically evaluates the recent studies on the modulation of total reduced GSH, GSH/GSSG redox couple, the major GSH-related enzymes and their cumulative significance in plants' adaptation and/or tolerance to TMs and metalloids in detail.

Asrar Z. et al. Calcium and L-histidine effects on ascorbate-glutathione cycle components under nickel-induced oxidative stress in tomato plants // Biologia Plantarum. 2014. Vol. 58, № 4. P. 709–716.

The effects of NiSO4, calcium, and L-histidine (His) on the components of ascorbate-glutathione cycle, antioxidant enzymes and lipid peroxidation in a tomato cultivar Early Urbana Y was investigated. The activities of enzymes including catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione reductase (GR), lipoxygenase (LOX), and phenylalanine ammonia lyase (PAL) were measured. In addition, the content of H2O2, ascorbate (ASC), dehydroascorbate (DHA), reduced glutathione (GSH), chlorophyll (Chl) a+b, carotenoids, proteins, malondialdehyde (MDA), membrane aldehydes, and electrolyte leakage (EL) were determined. Results suggest that the excess of Ni increased the content of H2O2, MDA, membrane aldehydes and proteins in roots as well as GPX, LOX, APX activities, and EL in leaves, whereas Ca and His ameliorated these effects. Moreover, decreasing leaf GSH and DHA content and GR activity were observed under the Ni stress, but these parameters were raised by Ca plus His treatment. However, no improvement in leaf protein, ASC, root GSH content, and activities of PAL and CAT were observed by using Ca or His under Ni stress.

Barrameda-Medina Y. et al. Role of GSH homeostasis under Zn toxicity in plants with different Zn tolerance // Plant Science. 2014. Vol. 227. P. 110–121.

Tripepthide glutathione (GSH) is a pivotal molecule in tolerance to heavy metals, including Zinc (Zn). The aim of our work is to examine the role of GSH metabolism in two different horticultural plants under Zn toxicity in order to select and/or generate plants tolerant to Zn toxicity. We show a comparative analysis of the toxic effect of 0.5 mM Zn between Lactuca sativa cv. Phillipus and Brassica oleracea cv. Bronco. In L. sativa the accumulation of Zn resulted in an increase in reactive oxygen species (ROS), while enzymes of GSH metabolism and the activities of the antioxidant enzymes were negatively affected. On the contrary, oleracea showed the existence of a detoxification mechanism of these ROS. Moreover, while in L sativa increased the oxidized GSH (GSSG) and phytochelatins (PCs) concentration with the reduction of leaves biomass, in B. oleracea the higher concentration of reduced GSH and its use in the detoxification of ROS seems to be a major mechanism to provide tolerance to Zn toxicity without reducing leaf biomass. Our results suggested that under Zn toxicity, B. oleracea is more efficient and tolerant than L sativa through the detoxification of lipid peroxidation products due to the reduced GSH.

Basantani M., Srivastava A. Plant glutathione transferases — a decade falls short // Canadian Journal of Botany. 2007. Vol. 85, № 5. P. 443–456.

The glutathione transferase (GST) superfamily in plants has been subdivided into eight classes, seven of which (phi, tau, zeta, theta, lambda, dehydroascorbate reductase, and tetrachlorohydroquinone dehalogenase) are soluble and one is microsomal. Since their identification in plants in 1970, these enzymes have been well established as phase II detoxification enzymes that perform several other essential functions in plant growth and development. These enzymes catalyze nucleophilic conjugation of the reduced form of the tripeptide glutathione to a wide variety of hydrophobic, electrophilic, and usually cytotoxic substrates. In plants, the conjugated product is either sequestered in the vacuole or transferred to the apoplast. The GSTs of phi and tau classes, which are plant-specific and the most abundant, are chiefly involved in xenobiotic metabolism. Zeta- and theta-class GSTs have very restricted activities towards xenobiotics. Theta-class GSTs are glutathione peroxidases and are involved in oxidative-stress metabolism, whereas zeta-class GSTs act as glutathione-dependent isomerases and catalyze the glutathione-dependent conversion of maleylacetoacetate to fumarylacetoacetate. Zeta-class GSTs participate in tyrosine catabolism. Dehydroascorbate reductase- and lambda-class GSTs function as thioltransferases. Microsomal-class GSTs are members of the MAPEG (membrane-associated proteins in eicosanoid and glutathione metabolism) superfamily. A plethora of studies utilizing both proteomics and genomics approaches have greatly helped in revealing the functional diversity exhibited by these enzymes. The three-dimensional structure of some of the members of the family has been described and this has helped in elucidating the mechanism of action and active-site amino-acid residues of these enzymes. Although a large amount of information is available on this complex enzyme superfamily, more research is necessary to answer additional questions such as, why are phi- and tau-class GSTs more abundant than GSTs from other classes? What functions do phi- and tau-class GSTs perform in plant taxa other than angiosperms? Do more GST classes exist? Future studies on GSTs should focus on these aspects.

Batkova P., Pospisilova J., Synkova H. Production of reactive oxygen species and development of antioxidative systems during in vitro growth and ex vitro transfer // Biologia Plantarum. 2008. Vol. 52, № 3. P. 413–422.

Ex vitro transfer is often stressful for in vitro grown plantlets. Water stress and photoinhibition, often accompanying the acclimatization of in vitro grown plantlets to ex vitro conditions, are probably the main factors promoting production of reactive oxygen species (ROS) and in consequence oxidative stress. The extent of the damaging effects of ROS depends on the effectiveness of the antioxidative systems which include low molecular mass antioxidants (ascorbate, glutathione, tocopherols, carotenoids, phenols) and antioxidative enzymes (superoxide dismutase, ascorbate peroxidase, catalase, glutathione reductase, monodehydroascorbate reductase, dehydroascorbate reductase). This review is focused on ROS production and development of antioxidative system during in vitro growth and their further changes during ex vitro transfer.

Chronopoulou E.G., Labrou N.E. Glutathione transferases: emerging multidisciplinary tools in red and green biotechnology. // Recent patents on biotechnology. 2009. Vol. 3, № 3. P. 211–223.

Cytosolic glutathione transferases (GSTs) are a diverse family of enzymes involved in a wide range of biological processes, many of which involve the conjugation of the tripeptide glutathione (GSH) to an electrophilic substrate. Detailed studies of GSTs are justified because of the considerable interest of these enzymes in medicine, agriculture and analytical biotechnology. For example, in medicine, GSTs are explored as molecular targets for the design of new anticancer drugs as a plausible means to sensitize drug-resistant tumors that overexpress GSTs. In agriculture, GSTs are exploited in the development of transgenic plants with increased resistance to biotic and abiotic stresses. Recently, selected isoenzymes of GSTs have found successful applications in the development of enzyme biosensors for the direct monitoring of environmental pollutants, such as herbicides and insecticides. This review article summarizes recent representative patents related to GSTs and their applications in biotechnology.

Dubreuil-Maurizi C., Poinssot B. Role of glutathione in plant signaling under biotic stress. // Plant signaling & behavior. 2012. Vol. 7, № 2. P. 210–212.

Glutathione (GSH) is a non-protein thiol compound which has been repeatedly reported to play an important role in plant responses during biotic stresses. However, our knowledge of glutathione-related molecular mechanisms underlying plant defense responses still remains limited. We first discovered that the Arabidopsis thaliana phytoalexin deficient 2-1 (pad2-1) mutant was linked to glutathione deficiency since the mutation was identified in the GSH1 gene encoding the first enzyme of glutathione biosynthesis: Glutamate Cysteine Ligase (GCL). Interestingly, this glutathione-deficient mutant pad2-1 also displays a high susceptibility to a wide range of invaders. We recently reported that the glutathione deficiency in pad2-1 is directly related to a low content of GCL protein. In parallel, we highlighted that the altered redox potential in pad2-1 upregulates the oxidative-stress marker genes GR1, GSTF6 and RbohD during infection with the hemibiotrophic oomycete Phytophthora brassicae. Moreover, the impairment of early signaling events such as plasma membrane depolarization, production of nitric oxide and reactive oxygen species also correlates with the reduced hypersensitive response (HR) observed during P. brassicae infection. Concerning the impaired salicylic acid (SA)-dependent pathway in pad2-1, our results indicated that transcripts of IsoChorismate Synthase1 (ICS1, a main enzyme of SA biosynthesis) do not accumulate in response to pathogen. In this review, we integrate previous knowledge and recent discoveries about pad2-1 to better understand the involvement of glutathione in the pad2-1 pleiotropic phenotype observed during biotic stresses.

Freeman J.L. et al. Constitutively elevated salicylic acid signals glutathione-mediated nickel tolerance in Thlaspi nickel hyperaccumulators // Plant Physiology. 2005. Vol. 137, № 3. P. 1082–1091.

Progress is being made in understanding the biochemical and molecular basis of nickel (Ni)/zinc (Zn) hyperaccumulation in Thlaspi; however, the molecular signaling pathways that control these mechanisms are not understood. We observed that elevated concentrations of salicylic acid (SA), a molecule known to be involved in signaling induced pathogen defense responses in plants, is a strong predictor of Ni hyperaccumulation in the six diverse Thlaspi species investigated, including the hyperaccumulators Thlaspi goesingense, Thlaspi rosulare, Thlaspi oxyceras, and Tlilaspi caerulescens and the nonaccumulators Thlaspi arvense and Thlaspi perfoliatum. Furthermore, the SA metabolites phenylalanine, cinnamic acid, salicyloyl-glucose, and catechol are also elevated in the hyperaccumulator T. goesingense when compared to the nonaccumulators Arabidopsis (Arabidopsis thaliana) and T arvense. Elevation of free SA levels in Arabidopsis, both genetically and by exogenous feeding, enhances the specific activity of serine acetyltransferase, leading to elevated glutathione and increased Ni resistance. Such SA-mediated Ni resistance in Arabidopsis phenocopies the glutathione-based Ni tolerance previously observed in Thlaspi, suggesting a biochemical linkage between SA and Ni tolerance in this genus. Intriguingly, the hyperaccumulator T. goesingense also shows enhanced sensitivity to the pathogen powdery mildew (Erysiphe cruciferarum) and fails to induce SA biosynthesis after infection. Nickel hyperaccumulation reverses this pathogen hypersensitivity, suggesting that the interaction between pathogen resistance and Ni tolerance and hyperaccumulation may have played a critical role in the evolution of metal hyperaccumulation in the Thlaspi genus.

Freeman J.L. et al. Increased glutathione biosynthesis plays a role in nickel tolerance in Thlaspi nickel hyperaccumulators // Plant Cell. 2004. Vol. 16, № 8. P. 2176–2191.

Worldwide more than 400 plant species are now known that hyperaccumulate various trace metals (Cd, Co, Cu, Mn, Ni, and Zn), metalloids (As) and nonmetals [Se) in their shoots. Of these, almost one-quarter are Brassicaceae family members, including numerous Thlaspi species that hyperaccumulate Ni up to 3% of there shoot dry weight. We observed that concentrations of glutathione, Cys, and O-acetyl-L-serine (OAS), in shoot tissue, are strongly correlated with the ability to hyperaccumulate Ni in various Thlaspi hyperaccumulators collected from serpentine soils, including Thlaspi goesingense, T. oxyceras, and T. rosulare, and nonaccumulator relatives, including T. perfoliatum, T. arvense, and Arabidopsis thaliana. Further analysis of the Austrian Ni hyperaccumulator T. goesingense revealed that the high concentrations of OAS, Cys, and GSH observed in this hyperaccumulator coincide with constitutively high activity of both serine acetyltransferase (SAT) and glutathione reductase. SAT catalyzes the acetylation Of L-Ser to produce OAS, which acts as both a key positive regulator of sulfur assimilation and forms the carbon skeleton for Cys biosynthesis. These changes in Cys and GSH metabolism also coincide with the ability of T. goesingense to both hyperaccumulate Ni and resist its damaging oxidative effects. Overproduction of T. goesingense SAT in the nonaccumulator Brassicaceae family member Arabidopsis was found to cause accumulation of OAS, Cys, and glutathione, mimicking the biochemical changes observed in the Ni hyperaccumulators. In these transgenic Arabidopsis, glutathione concentrations strongly correlate with increased resistance to both the growth inhibitory and oxidative stress induced effects of Ni. Taken together, such evidence supports our conclusion that elevated GSH concentrations, driven by constitutively elevated SAT activity, are involved in conferring tolerance to Ni-induced oxidative stress in Thlaspi Ni hyperaccumulators.

Gajewska E. et al. Differential response of wheat roots to Cu, Ni and Cd treatment: oxidative stress and defense reactions // Plant Growth Regulation. 2013. Vol. 71, № 1. P. 13–20.

Wheat seedlings cv. Zyta were treated with Cu, Ni and Cd at the concentrations causing approximately 50 % root growth inhibition, i.e. 12.5, 50 and 60 mu M, respectively. Tissue metal accumulation, membrane permeability, lipid peroxidation, protein oxidation, concentration of thiol compounds as well as protease, glutathione S-transferase (GST) and peroxidase (POD) activities were studied in roots after 7 days of metal exposure. The metals showed different concentrations in root tissues with Cu and Cd being accumulated to the smallest and to the greatest extent, respectively. Membrane permeability was significantly enhanced by Cu and Ni but not by Cd treatment. All metals induced similar increase in protein oxidation, while significant enhancement of lipid peroxidation was observed only in the case of Cu treatment. The detected thiol compounds: cysteine (Cys), homocysteine (Hcy), gamma-glutamylcysteine (gamma-GluCys) and glutathione (GSH) were differently influenced by the metal treatment. Ni appeared to be the most effective inductor of GSH accumulation while both Cu and Ni similarly increased Cys content in the roots. Accumulation of gamma-GluCys was found in response to Cu and Cd applications. Concentration of Hcy was enhanced by Cd treatment but exposure to Ni decreased its content below the level of detection. The activity of GST was considerably elevated by Cd and Ni treatments, while POD activity was increased only in response to Cu application. Our study showed that wheat roots differently responded to treatment with metals used at the concentrations having similar impact on growth.

Gajewska E., Sklodowska M. Effect of nickel on ROS content and antioxidative enzyme activities in wheat leaves // Biometals. 2007. Vol. 20, № 1. P. 27–36.

Influence of 100 mu M Ni on growth, Ni accumulation, O-2(.-), H2O2 and lipid peroxides contents as well as the activities of superoxide dismutase ( SOD), catalase ( CAT), ascorbate peroxidase (APX), guaiacol peroxidase ( POD) and glutathione peroxidase ( GSH-Px) were studied in the leaves of wheat plants on the 3rd, 6th and 9th days after treatment. Exposure of the plants to Ni for only 3 days led to almost 200-fold increase in this metal concentration in the leaf tissue but later the rate of Ni accumulation was much slower. Length and fresh weight of the leaves were substantially reduced, up to 25% and 39%, respectively at the end of experiment. Visible symptoms of Ni toxicity: chlorosis and necrosis were observed following the 3rd day. Treatment with Ni resulted in the increase in O-2(.-) and H2O2 contents in the leaves. Both showed their highest values, approximately 250% of those of the control, on the 3rd day and then their levels decreased but still markedly exceeded the control values. SOD and CAT activities decreased signicantly in response to Ni treatment, however a several-fold increase in APX and POD activities was found. No significant changes in lipid peroxides content were observed in the leaves after Ni application. The activity of GSH-Px showed a 29% induction on the 3rd day. Our results indicated that despite prolonged increases in O-2(.-) and H2O2 levels, oxidative damage, measured as the level of lipid peroxidation, did not occur in the leaves of Ni-treated wheat.

Garg N., Manchanda G. ROS generation in plants: Boon or bane? // Plant Biosystems. 2009. Vol. 143, № 1. P. 81–96.

Reactive oxygen species (ROS, partially reduced or activated derivatives of oxygen), are highly reactive and toxic and can lead to oxidative destruction of the cell. ROS production increases when plants are exposed to different kinds of stresses. The chief toxic effect of O2 - and H2O2 resides in their ability to initiate cascade reactions that result in the production of the hydroxyl radical and other destructive species such as lipid peroxides. These dangerous cascades are prevented by efficient operation of the cell's antioxidant defenses. However, in addition to their role as toxic byproducts of aerobic metabolism, recently, a new role for ROS has been identified, i.e. the control and regulation of biological processes, such as growth, cell cycle, programmed cell death, hormone signaling, biotic and abiotic stress responses, and development. This review discusses the biochemical properties and sources and sites of ROS production, ROS-scavenging systems, and the role of ROS as signaling molecules.

Gratao P.L. et al. Antioxidant response of Nicotiana tabacum cv. Bright Yellow 2 cells to cadmium and nickel stress // Plant Cell Tissue and Organ Culture. 2008. Vol. 94, № 1. P. 73–83.

Plant cell cultures are a suitable model system for investigation of the physiological mechanisms of tolerance to environmental stress. We have determined the effects of Cd (0.1 and 0.2 mM CdCl(2)) and Ni (0.075 and 0.75 mM NiCl(2)) on Nicotiana tabacum L. cv. Bright Yellow (TBY-2) cell suspension cultures over a 72-h period. Inhibition of growth, loss of cell viability and lipid peroxidation occurred, in general, only when the TBY-2 cells were grown at 0.2 mM CdCl(2) and at 0.75 mM NiCl(2). At 0.1 mM CdCl(2), a significant increase in growth was determined at the end of the experiment. Increases in the activities of all of the four enzymatic antioxidant defence systems tested, were induced by the two concentrations of Cd and Ni, but at different times during the period of metal exposure. Overall, the cellular antioxidant responses to Cd and Ni were similar and were apparently sufficient to avoid oxidative stress at the lower concentrations of Cd and Ni. The activities of glutathione reductase and glutathione S-transferase increased early but transiently, whereas the activities of catalase and guaiacol peroxidase increased in the latter half of the experimental period. Therefore it is likely that the metabolism of reduced glutathione was enhanced during the initial onset of the stress, while catalase and guaiacol-type peroxidase appeared to play a more important role in the antioxidant response once the stress became severe.

Haensch R., Mendel R.R. Physiological functions of mineral micronutrients (Cu, Zn, Mn, Fe, Ni, Mo, B, Cl) // Current Opinion in Plant Biology. 2009. Vol. 12, № 3. P. 259–266.

Micronutrients are involved in all metabolic and cellular functions. Plants differ in their need for micronutrients, and we will focus here only on those elements that are generally accepted as essential for all higher plants: boron (B), chloride (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn). Several of these elements are redoxactive that makes them essential as catalytically active cofactors in enzymes, others have enzyme-activating functions, and yet others fulfill a structural role in stabilizing proteins. In this review, we focus on the major functions of mineral micronutrients, mostly in cases where they were shown as constituents of proteins, making a selection and highlighting some functions in more detail.

Hong-Yan Sun1,2, Xiao-Yun Wang3, Hua-Xin Dai1, Guo-Ping Zhang1 and Fei-Bo Wu1,Effect of Exogenous Glutathione and Selenium on Cadmium-Induced Changes in Cadmium and Mineral Concentrations and Antioxidative Metabolism in Maize Seedlings // Asian Journal of Chemistry. 2013. Vol. 25, № 6. P. 2970-2976.

A hydroponic experiment was carried out to study the modulation of exogenous reduced glutathione and selenium in antioxidant defense system and microelement uptake against cadmium-toxicity in maize seedlings. The results showed that 50 ?M cadmium increased accumulation of H2O2 and malondialdehyde but reduced plant height, root length, chlorophyll content (SPAD value) and biomass. Antioxidant enzyme activities of root/leaf peroxidase and leaf superoxide dismutase increased significantly under cadmium stress, while leaf catalase decreased significantly. Moreover, cadmium-stress reduced manganese concentrations both in shoots and roots. Significantly negative correlation was discovered between manganese and cadmium concentration in different plant organs. Addition of 2.5 ?M selenium or pretreated with 100 ?M glutathione for 24 h significantly alleviated cadmium-induced growth inhibition and dramatically diminished leaf H2O2 and root malondialdehyde accumulation. Se addition or glutathione pretreatment significantly decreased cadmium concentration in roots/shoots, increased root iron level, while glutathione reduced zinc uptake. Furthermore, GSH/Se counteracted cadmium-induced alterations of certain antioxidant enzymes, e.g. brought root/leaf peroxidase and leaf superoxide dismutase activities down towards to the control level, but elevated root ascorbate peroxidase activity. These data suggest that reduced cadmium concentration and diminished cadmium-induced H2O2 and malondialdehyde accumulation in plants could be principal protective mechanism for the exogenous glutathione/selenium against cadmium toxicity. - See more at: http://www.asianjournalofchemistry.co.in/user/journal/viewarticle.aspx?ArticleID=25_6_8#sthash.aNgfeH4z.dpuf

Jozefczak M. et al. Glutathione Is a Key Player in Metal-Induced Oxidative Stress Defenses // International Journal of Molecular Sciences. 2012. Vol. 13, № 3. P. 3145–3175.

Since the industrial revolution, the production, and consequently the emission of metals, has increased exponentially, overwhelming the natural cycles of metals in many ecosystems. Metals display a diverse array of physico-chemical properties such as essential versus non-essential and redox-active versus non-redox-active. In general, all metals can lead to toxicity and oxidative stress when taken up in excessive amounts, imposing a serious threat to the environment and human health. In order to cope with different kinds of metals, plants possess defense strategies in which glutathione (GSH; gamma-glu-cys-gly) plays a central role as chelating agent, antioxidant and signaling component. Therefore, this review highlights the role of GSH in: (1) metal homeostasis; (2) antioxidative defense; and (3) signal transduction under metal stress. The diverse functions of GSH originate from the sulfhydryl group in cysteine, enabling GSH to chelate metals and participate in redox cycling.

Kafel A. et al. The effects of Aphis fabae infestation on the antioxidant response and heavy metal content in field grown Philadelphus coronarius plants // Science of the Total Environment. 2010. Vol. 408, № 5. P. 1111–1119.

The purpose of this study was to explore a possible relationship between the soil availability of metals and their concentrations in various parts of Philadelphus coronarius plants. Moreover, the possible impact of an aphid infestation on the contamination and antioxidant response of plants from the urban environment of Krakow and the reference rural area of Zagaje Stradowskie (southern Poland) was analyzed. The contents of the glutathione, proline, non-protein -SH groups, antioxidants, and phosphorous and the levels of guaiacol peroxidase and catalase activity in leaves and shoots either infested or not by the aphid Aphis fabae Scop., were measured. The potential bioavailability of metals (Cd; Cu; Ni; Pb; Zn) in the soil and their concentrations in A coronarius plants originating from both sites were compared. The antioxidant responses were generally elevated in the plants in the polluted area. Such reactions were additionally changed by aphid infestation. Generally, the concentrations of metals in the HNO(3) and CaCl(2) extractants of the soils from two layers at the 0-20 and 20-40 cm depths from the polluted area were higher than in those from the reference area. Such differences were found for nickel and lead (in all examined extractants), zinc (in soil extractants from the layer at 20-40 cm) and cadmium (in HNO(3) extractants). Significant positive relationships between the lead concentrations in the soil and in the plants were found. In the parts of plants from the polluted area, higher concentrations of Pb and Zn (leaves and shoots) and Cd (shoots) were recorded. The shoots and leaves of plants infested with aphids had higher concentrations of Zn but lower Pb. Moreover, their leaves had higher contaminations of Cu and Ni. in conclusion, aphids affected not only the antioxidant response of the plants but also their contamination with metals. especially contamination of the leaves.

Kenderesova L. et al. Early Zn2+-induced effects on membrane potential account for primary heavy metal susceptibility in tolerant and sensitive Arabidopsis species // Annals of Botany. 2012. Vol. 110, № 2. P. 445–459.

Uptake of heavy metals by plant root cells depends on electro-physiological parameters of the plasma membrane. In this study, responses of the plasma membrane in root cells were analysed where early reactions to the metal ion-induced stress are localized. Three different Arabidopsis species with diverse strategies of their adaptation to heavy metals were compared: sensitive Arabidopsis thaliana and tolerant A. halleri and A. arenosa. Plants of A. thaliana Col-0 ecotype and plants of A. arenosa and A. halleri originating from natural metallicolous populations were exposed to high concentrations of Zn-2. Plants were tested for root growth rate, cellular tolerance, plant morphology and cell death in the root apex. In addition, the membrane potential (E-M) of mature cortical root cells and changes in the pH of the liquid culture media were measured. Primary roots of A. halleri and A. arenosa plants grew significantly better at increased Zn-2 concentrations than A. thaliana plants. Elevated Zn-2 concentrations in the culture medium induced rapid changes in E-M. The reaction was species-specific and concentration-dependent. Arabidopsis halleri revealed the highest insensitivity of the plasma membrane and the highest survival rate under prolonged treatment with extra-high concentrations. Plants were able to effectively adjust the pH in the control, but much less at Zn-2-induced lower pH. The results indicate a similar mode of early reaction to Zn-2, but with different extent in tolerant and sensitive species of Arabidopsis. The sensitivity of A. thaliana and a high tolerance of A. halleri and A. arenosa were demonstrated. Plasma membrane depolarization was lowest in the hyperaccumulator A. halleri and highest in A. thaliana. This indicates that rapid membrane voltage changes are an excellent tool to monitor the effects of heavy metals.

Kral’ova K., Jampilek J., Ostrovsky I. Metabolomics - Useful Tool for Study of Plant Responses to Abiotic Stresses // Ecological Chemistry and Engineering S-Chemia I Inzynieria Ekologiczna S. 2012. Vol. 19, № 2. P. 133–161.

Abiotic stresses are produced by inappropriate levels of physical components of the environment and cause plant injury through unique mechanisms that result in specific responses. Metabolomics is a relatively new approach aimed at improved understanding of metabolic networks and the subsequent biochemical composition of plants and other biological organisms. The paper is focused on the use of metabolomics, metabolic profiling and metabolic fingerprinting to study plant responses to some environmental stresses (eg elevated temperature, chilling and freezing, drought, high salinity, UV radiation, high ozone levels, nutrient deficiency, oxidative stress, herbicides and heavy metals). Attention is also devoted to the effects of some environmental factors on plants such as high or low levels of CO2 or different levels of irradiance. Alterations of plants metabolites due to multiple abiotic stresses (drought-heat, drought-salinity, elevated CO2-salinity) are analysed as well. In addition, metabolomic approach to study plant responses to some artificial abiotic stresses, mechanical stress or pulsed electric field-induced stress is discussed. The most important analytical methods applied in metabolomics are presented and perspectives of metabolomics exploitation in the future are outlined, too.

Kumar P. et al. Effect of nickel and grafting combination on yield, fruit quality, antioxidative enzyme activities, lipid peroxidation, and mineral composition of tomato // Journal of Plant Nutrition and Soil Science. 2015. Vol. 178, № 6. P. 848–860.

Soil contamination by heavy metals negatively affects crop productivity, besides representing serious threat to human health. Grafting tomato onto appropriate rootstocks may raise Ni tolerance through limiting heavy metal uptake by roots and/or its translocation to the shoot and by detoxification. A greenhouse experiment was conducted to determine the influence of long-term Ni exposure (0, 25, or 50 mu M) on crop productivity, fruit quality, leaf chlorophyll content, fluorescence, electrolyte leakage, catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX) activities in leaf, proline content, membrane lipid peroxidation, and mineral composition of tomato plants cv. Ikram, either self-grafted or grafted onto three rootstocks: Black Beauty, Unifort, and Maxifort. Significant reduction in yield was observed in response to an increase in Ni concentration with more detrimental effects at 50 mu M Ni. The fruit dry matter and total soluble solids content increased under severe Ni stress. The depression of crop performance under Ni toxicity was attributed to a decrease in leaf pigments (SPAD index), efficiency of PSII, macroand microelements, and increase in lipid peroxidation and membrane damage. Plants grafted onto tomato rootstocks Maxifort and Unifort exhibited higher chlorophyll content, photochemical activity of PSII, antioxidant activity of APX and GPX, lower accumulation of MDA, and a better nutritional status (higher Ca and Fe, and lower Ni) in the leaf tissues in comparison with selfgrafted plants and those grafted onto Black Beauty. Plants grafted onto tomato rootstocks Unifort and especially Maxifort could minimize the nickel toxicity by improving nutritional status and detoxification processes.

Labudda M., Azam F.M.S. Glutathione-dependent responses of plants to drought: A review // Acta Societatis Botanicorum Poloniae. 2014. Vol. 83, № 1. P. 3–12.

Water is a renewable resource. However, with the human population growth, economic development and improved living standards, the world's supply of fresh water is steadily decreasing and consequently water resources for agricultural production are limited and diminishing. Water deficiency is a significant problem in agriculture and increasing efforts are currently being made to understand plant tolerance mechanisms and to develop new tools (especially molecular) that could underpin plant breeding and cultivation. However, the biochemical and molecular mechanisms of plant water deficit tolerance are not fully understood, and the data available is incomplete. Here, we review the significance of glutathione and its related enzymes in plant responses to drought. Firstly, the roles of reduced glutathione and reduced/oxidized glutathione ratio, are discussed, followed by an extensive discussion of glutathione related enzymes, which play an important role in plant responses to drought. Special attention is given to the S-glutathionylation of proteins, which is involved in cell metabolism regulation and redox signaling in photosynthetic organisms subjected to abiotic stress. The review concludes with a brief overview of future perspectives for the involvement of glutathione and related enzymes in drought stress responses.

Leitenmaier B., Kupper H. Cadmium uptake and sequestration kinetics in individual leaf cell protoplasts of the Cd/Zn hyperaccumulator Thlaspi caerulescens // Plant, Cell & Environment. 2011. Vol. 34, № 2. P. 208–219.

Hyperaccumulators store accumulated metals in the vacuoles of large leaf epidermal cells (storage cells). For investigating cadmium uptake, we incubated protoplasts obtained from leaves of Thlaspi caerulescens (Ganges ecotype) with a Cd-specific fluorescent dye. A fluorescence kinetic microscope was used for selectively measuring Cd-uptake and photosynthesis in different cell types, so that physical separation of cell types was not necessary. Few minutes after its addition, cadmium accumulated in the cytoplasm before its transport into the vacuole. This demonstrated that vacuolar sequestration is the rate-limiting step in cadmium uptake into protoplasts of all leaf cell types. During accumulation in the cytoplasm, Cd-rich vesicle-like structures were observed. Cd uptake rates into epidermal storage cells were higher than into standard-sized epidermal cells and mesophyll cells. This shows that the preferential heavy metal accumulation in epidermal storage cells, previously observed for several metals in intact leaves of various hyperaccumulator species, is due to differences in active metal transport and not differences in passive mechanisms like transpiration stream transport or cell wall adhesion. Combining this with previous studies, it seems likely that the transport steps over the plasma and tonoplast membranes of leaf epidermal storage cells are driving forces behind the hyperaccumulation phenotype.

Lin Y.-F., Aarts M.G.M. The molecular mechanism of zinc and cadmium stress response in plants // Cellular and Molecular Life Sciences. 2012. Vol. 69, № 19. P. 3187–3206.

When plants are subjected to high metal exposure, different plant species take different strategies in response to metal-induced stress. Largely, plants can be distinguished in four groups: metal-sensitive species, metal-resistant excluder species, metal-tolerant non-hyperaccumulator species, and metal-hypertolerant hyperaccumulator species, each having different molecular mechanisms to accomplish their resistance/tolerance to metal stress or reduce the negative consequences of metal toxicity. Plant responses to heavy metals are molecularly regulated in a process called metal homeostasis, which also includes regulation of the metal-induced reactive oxygen species (ROS) signaling pathway. ROS generation and signaling plays an important duel role in heavy metal detoxification and tolerance. In this review, we will compare the different molecular mechanisms of nutritional (Zn) and non-nutritional (Cd) metal homeostasis between metal-sensitive and metal-adapted species. We will also include the role of metal-induced ROS signal transduction in this comparison, with the aim to provide a comprehensive overview on how plants cope with Zn/Cd stress at the molecular level.

Liu D., Liu Y., Rao J., Wang G., Li H., Ge F., Chen C. Сверхэкспрессия гена глутатион-S-трансферазы из плодов Pyrus pyrifolia повышает устойчивость трансгенных растений табака к абиотическому стрессу // Молекулярная биология. 2013. Т. 47. № 4. С. 591-601.

Глутатион-S-трансферазы (GST) - многофункциональные белки, широко распространенные у животных и растений. GST кодируются большими семействами генов, они участвуют в ответе на окислительный стресс, вызываемый засухой, действием тяжелых металлов, солей и т.п. В условиях окислительного стресса избыток активных форм кислорода (АФК) индуцирует повышение уровня GST, которые метаболизируют токсические продукты перекисного окисления липидов, повреждающие ДНК и другие компоненты клеток. Ранее охарактеризовали полную кДНК нового гена GSTZ (PpGST) из плодов Pyrus pyrifolia Nakai cv Huobali. В представленной работе сконструировали вектор для конститутивной экспрессии РрGST в растениях и перенесли его в растения табака (Nicotiana tabacum L. cv Xanthi) для изучения функций PpGST. Показано, что ген PpGST успешно встраивается в геном растений табака. Экспрессия гена PpGST в трансгенных линиях табака подтверждена методами Саузерн-блотинга и количественной обратной транскрипции?полимеразной цепной реакции. Растения поколения Т1, полученные как из трансгенных линий, так и из растений дикого типа, одинаково росли в нестрессовых условиях. Однако при стрессе, вызванном недостатком влаги, действием NaCl и кадмия (Cd), трансгенные растения росли почти нормально. Более того, в трансгенных линиях табака Т1 скорость продукции супероксидного аниона в условиях абиотического стресса была значительно ниже, чем в растениях дикого типа. При этом содержание малонового диальдегида в трансгенных растениях табака Т1 лишь слегка возрастало при стрессе и было значительно ниже, чем в растениях дикого типа. Сверхэкспрессия PpGST повышала активность GST и одновременно с этим устойчивость трансгенных линий табака к окислительному стрессу.

Llugany M. et al. Cadmium-induced changes in glutathione and phenolics of Thlaspi and Noccaea species differing in Cd accumulation // Journal of Plant Nutrition and Soil Science. 2013. Vol. 176, № 6. P. 851–858.

Glutathione (GSH) and phenolics play an important role in plant defense against metal-ion toxicity. The antioxidant activity and metal-binding capacity of these compounds can account for the protective effects. In contrast to animal-cell models, however, the possible interplay among these substances in stress defense of plants is poorly investigated. This study compares the influence of cadmium (Cd) on the profiles of both soluble phenolics and GSH in shoots of different Thlaspi and Noccaea species: two ecotypes of the nonhyperaccumulator T. arvense differing in Cd resistance (ecotype Aigues Vives, Cd-sensitive, and ecotype Jena, Cd-resistant) and two Cd-tolerant Cd-Zn hyperaccumulators N. praecox and N. caerulescens (formerly Thlaspi praecox and T. caerulescens). To reveal the possible influence of Cd-induced sulfur (S) shortage on the stress response, plants receiving normal S concentrations (500 M MgSO4) and plants treated with surplus S (500 M MgSO4 + 500 M K2SO4) were analyzed. Our working hypothesis was that species differences in tolerance to high tissue Cd concentrations should be reflected by differences in endogenous levels of GSH and phenolic compounds. The results reveal clear species-dependent differences in both the constitutive patterns and the Cd- and S-induced changes in shoot concentrations of GSH and phenolics. However, no simple relationship between these shoot concentrations and Cd accumulation and tolerance can be established.

Lyubenova L. et al. Comparative study on the impact of copper sulphate and copper nitrate on the detoxification mechanisms in Typha latifolia // Environmental Science and Pollution Research. 2015. Vol. 22, № 1. P. 657–666.

The present study focused on cupric sulphate and cupric nitrate uptake in Typha latifolia and the impact of these copper species on the plant’s detoxification capacity. When the plants were exposed to 10, 50 and 100 ?M cupric sulphate or cupric nitrate, copper accumulation in T. latifolia roots and shoots increased with rising concentration of the salts. Shoot to root ratios differed significantly depending on the form of copper supplementation, e.g. if it was added as cupric (II) sulphate or cupric (II) nitrate. After incubation with 100 ?M of cupric sulphate, up to 450 mg Cu/kg fresh weight (FW) was accumulated, whereas the same concentration of cupric nitrate resulted in accumulation of 580 mg/kg FW. Furthermore, significant differences in the activity of some antioxidative enzymes in Typha roots compared to the shoots, which are essential in the plant’s reaction to cope with metal stress, were observed. The activity of peroxidase (POX) in roots was increased at intermediate concentrations (10 and 50 ?M) of CuSO4, whereas it was inhibited at the same Cu(NO3)2 concentrations. Ascorbate peroxidase (APOX) and dehydroascorbate reductase (DHAR) increased their enzyme activity intensely, which may be an indication for copper toxicity in T. latifolia plants. Besides, fluorodifen conjugation by glutathione S-transferases (GSTs) was increased up to sixfold, especially in roots.

Maheshwari R., Dubey R.S. Nickel-induced oxidative stress and the role of antioxidant defence in rice seedlings // Plant Growth Regulation. 2009. Vol. 59, № 1. P. 37–49.

Seedlings of rice (Oryza sativa L.) cv. Pant-12 grown in sand cultures containing 200 and 400 mu M NiSO4, showed a decrease in length and fresh weight of roots and shoots. Nickel was readily taken up by rice seedlings and the concentration was higher in roots than shoots. Nickel-treated seedlings showed increased rates of superoxide anion (O (2) (aEuro cent a') ) production, elevated levels of H2O2 and thiobarbituric acid reactive substances (TBARS) demonstrating enhanced lipid peroxidation, and a decline in protein thiol levels indicative of increased protein oxidation compared to controls. With progressively higher Ni concentrations, non-protein thiol and ascorbate (AsA) increased, whereas the level of low-molecular-weight thiols (such as glutathione and hydroxyl-methyl glutathione), the ratio of these thiols to their corresponding disulphides, and the ratio of AsA to dehydroascorbic acid declined in the seedlings. Among the antioxidant enzymes studied, the activities of all isoforms of superoxide dismutase (Cu-Zn SOD, Mn SOD and Fe SOD), guaiacol peroxidases (GPX) and ascorbate peroxidase (APX) increased in Ni-treated seedlings, while no clear alteration in catalase activity was evident. Activity of the ascorbate-glutathione cycle enzymes monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR)-significantly increased in Ni-treated seedlings. However such increase was apparently insufficient to maintain the intracellular redox balance. Results suggest that Ni induces oxidative stress in rice plants, resulting in enhanced lipid peroxidation and decline in protein thiol levels, and that (hydroxyl-methyl) glutathione and AsA in conjunction with Cu-Zn SOD, GPX and APX are involved in stress response.

Malecka A. et al. Response of the pea roots defense systems to the two-element combinations of metals (Cu, Zn, Cd, Pb) // Acta Biochimica Polonica. 2014. Vol. 61, № 1. P. 23–28.

The presence of the single metals (Cd, Pb, Cu, Zn) induces ROS (reactive oxygen species) production and causes oxidative stress in plants. While applied in two-element combinations, trace metals impact organisms in a more complex way. To assess the resultant effect we treated the pea grown hydroponically with the trace metals in variants: CuPb, CuCd, CuZn, PbCd, ZnPb, ZnCd in concentrations of 25 for each metal ion. Abiotic stress inhibited root elongation growth, decreased biomass production, induced changes in root colour and morphology. It changed rate of ROS production, malondialdehyde content, increased activity and altered gene expression of defence enzymes (superoxide dysmutase, catalase, ascorbate peroxidase, glutathione reductase, gamma-glutamylcysteine synthetase).

Mendoza-Cozatl D. et al. Sulfur assimilation and glutathione metabolism under cadmium stress in yeast, protists and plants // Fems Microbiology Reviews. 2005. Vol. 29, № 4. P. 653–671. +B16

Glutathione (gamma-glu-cys-gly; GSH) is usually present at high concentrations in most living cells, being the major reservoir of nonprotein reduced sulfur. Because of its unique redox and nucleophilic properties, GSH serves in bio-reductive reactions as an important line of defense against reactive oxygen species, xenobiotics and heavy metals. GSH is synthesized from its constituent amino acids by two ATP-dependent reactions catalyzed by gamma-glutamylcysteine synthetase and glutathione synthetase. In yeast, these enzymes are found in the cytosol, whereas in plants they are located in the cytosol and chloroplast. In protists, their location is not well established. In turn, the sulfur assimilation pathway, which leads to cysteine biosynthesis, involves high and low affinity sulfate transporters, and the enzymes ATP sulfurylase, APS kinase, PAPS reductase or APS reductase, sulfite reductase, serine acetyl transferase, O-acetylserine/O-acetylhomoserine sulfhydrylase and, in some organisms, also cystathionine beta-synthase and cystathionine gamma-lyase. The biochemical and genetic regulation of these pathways is affected by oxidative stress, sulfur deficiency and heavy metal exposure. Cells cope with heavy metal stress using different mechanisms, such as complexation and compartmentation. One of these mechanisms in some yeast, plants and protists is the enhanced synthesis of the heavy metal-chelating molecules-GSH and phytochelatins, which are formed from GSH by phytochelatin synthase (PCS) in a heavy metal-dependent reaction; Cd(2+) is the most potent activator of PCS. In this work, we review the biochemical and genetic mechanisms involved in the regulation of sulfate assimilation-reduction and GSH metabolism when yeast, plants and protists are challenged by Cd(2+)

Mohsenzadeh S. et al. Plant glutathione S-transferase classification, structure and evolution // African Journal of Biotechnology. 2011. Vol. 10, № 42. P. 8160–8165.

Glutathione S-transferases are multifunctional proteins involved in diverse intracellular events such as primary and secondary metabolisms, stress metabolism, herbicide detoxification and plant protection against ozone damages, heavy metals and xenobiotics. The plant glutathione S-transferase superfamily have been subdivided into eight classes. Phi, tau, zeta, theta, lambda, dehydroascorbate reductase and tetrachlorohydroquinone dehalogenase classes are soluble and one class is microsomal. Glutathione S-transferases are mostly soluble cytoplasmic enzymes. To date, the crystal structures of over 200 soluble glutathione S-transferases, present in plants, animals and bacteria have been resolved. The structures of glutathione S-transferase influence its function. Phylogenetic analysis suggests that all soluble glutathione S-transferases have arisen from an ancient progenitor gene, through both convergent and divergent pathways.

Muller M. et al. Recent developments in methods intracellulary localizing glutathione within plant tissues and cells (a minireview) // Phyton-Annales Rei Botanicae. 2005. Vol. 45, № 3. P. 45–55.

This article reviews the current knowledge of the intracellular distribution of glutathione (GSH and t-GSH) in different plants and plant tissues under various abiotic and biotic stress situations and artificial modulations of glutathione contents. Monochlorobimane fluorescence of GSH is described for light microscopical investigations allowing GSH in cytoplasm and in the nucleus to be distinguished. Further, a specific antibody, which recognizes t-GSH, was used in order to demonstrate the distribution of glutathione in different cell compartments for light and electron microscopical investigations. The labeling shows different glutathione contents in the cell compartments with high staining intensity in mitochondria.

Nadgorska-Socha A. et al. Accumulation of heavy metals and antioxidant responses in Vicia faba plants grown on monometallic contaminated soil // Environmental Science and Pollution Research. 2013. Vol. 20, № 2. P. 1124–1134.

The purpose of this study was to explore the effects of soil contamination by selected metals (cadmium, copper, nickel, lead or zinc) on the antioxidant response of Vicia faba plants. The levels of the antioxidants: glutathione, proline, non-protein thiols, as well as guaiacol peroxidase and catalase activities were measured in the upperparts of plants. Additionally, the potential bioavailability of metals in the soil and their concentrations in V. faba plants were compared. Treatment with metal caused the problem of an elevation in its bioavailability in soil and its concentration in leaves and stems. The most serious problems seemed to be metal elevations in soil, especially Zn and Ni as well as in the aerial parts of V. faba plants. The antioxidant responses appeared to be metal specific. The elevation of guaiacol peroxidase activity in leaves and stems as well as the proline in leaves was the only more general reaction to metal exposure. Upon analysis of the effects of soil metal contamination on V. faba plants, we recommend the use of some measurements such as guaiacol peroxidase activity and proline level as useful tools in biological monitoring.

Nowicka B. et al. Prenyllipid antioxidants participate in response to acute stress induced by heavy metals in green microalga Chlamydomonas reinhardtii // Environmental and Experimental Botany. 2016. Vol. 123. P. 98–107.

The induction of oxidative stress is an important mechanism of heavy metal toxicity. That is why, isoprenoid antioxidants, such as chromanols and prenylquinones, are thought to participate in the response to heavy metal-induced stress. In the present study, we performed a comparative analysis of the prenyllipid and pigment content and lipid peroxides in Chlamydomonas reinhardtii during 7.5 h of acute stress induced by Cu, Cr, Cd, Hg and Ag ions. We also measured the expression of genes encoding enzymes participating in the detoxification of reactive oxygen species (APX1, CAT1, FSD1, MSD1) and a gene required for a.-tocopherol and plastoquinone biosynthesis (VTE3). In an AgNO3-treated culture, pigments and prenyllipids were degraded at the same rate. The significant peroxidation of lipids was also observed. For other metals, a different pattern of changes in pigment and prenyllipid content was observed. The significant degradation of pigments was observed during the response to Cu2+. The decrease in prenyllipid content occurred in Cu and Cr-stressed algae. Massive oxidation of plastoquinol was observed in the presence of Cu2+, Ag+ and Cr2O72-. The most pronounced increase in the expression of the investigated genes was found in the presence of Cu2+ and Hg2+ ions. The genes whose expression was the most up-regulated were APX1, MSD1, VTE3.

Nunes B. et al. Chronic Effects of Realistic Concentrations of Non-essential and Essential Metals (Lead and Zinc) on Oxidative Stress Biomarkers of the Mosquitofish, Gambusia holbrooki // Archives of Environmental Contamination and Toxicology. 2015. Vol. 69, № 4. P. 586–595.

Metallic contamination is widespread, particularly in areas impacted by human activities. Human activities result in high loads of metals being discarded into the aquatic compartment, reinforcing the need to evaluate their toxic effects especially on exposed fish. The purpose of this study was to determine the toxic response (namely, antioxidant levels and lipoperoxidative damage) in both liver and gills of the freshwater fish species Gambusia holbrooki, exposed to lead and zinc. Fish were exposed for 28 days (chronic exposure) to ecologically relevant concentrations of the selected compounds. The following oxidative stress/damage biomarkers were evaluated: glutathione-S-transferases (GSTs), glutathione reductase (GR), and thiobarbituric acid reactive substances (TBARS). The results indicate that lead caused a significant oxidative response, with significant increase of the enzymatic antioxidant defense (GSTs activity in hepatic tissue, and GR activity in branchial tissue) of exposed organisms. On the other hand, zinc caused a significant inhibition of G. holbrooki hepatic GR, a biological response that may be related to the antioxidant activity exhibited by this metal. The obtained results are of high importance, especially if one considers that the obtained toxic responses occurred at low, albeit ecologically relevant, levels of exposure.

Ogawa K. Glutathione-associated regulation of plant growth and stress responses // Antioxidants & Redox Signaling. 2005. Vol. 7, № 7-8. P. 973–981.

A reduced form of glutathione (GSH) is considered to protect the cell from oxidative damage, based on its redox buffering action and abundance in the cell. However, in plants, the high redox potential molecule ascorbate exists at comparable or higher concentrations and is used for scavenging hydrogen peroxide as an electron donor. Recently, examples that cannot be explained simply by the antioxidant activity of GSH have been increasing in number. This article summarizes the recent findings on the glutathione-associated events in plants, in particular, growth and development including cell differentiation, cell death and senescence, pathogen resistance, and enzymatic regulation.

Oztetik E. A tale of plant Glutathione S-transferases: Since 1970 // Botanical Review. 2008. Vol. 74, № 3. P. 419–437.

Ubiquitously distributed multifunctional superfamily of Glutathione S-transferases (GST) generally constitute a dimeric enzymes and catalyse the conjugation of the thiol group of the glutathione (GSH) to diverse electrophilic centres on lipophilic molecules with the formation of rather less active end products. Besides their well investigated conjugation reaction for the detoxification of endogenous and xenobiotic compounds, they can also be involved in both GSH dependent peroxidation or isomerization reactions, and several other non-catalytic functions, like binding of non-substrate ligands, stress-induced signalling processes and preventing of apoptosis. Plant GSTs have been a focus of attention because of their roles in herbicide detoxification and today seven distinct classes of soluble (cytosolic) GSTs are presented as Phi, Tau, Theta, Zeta, Lambda, Dehydroascorbate reductases (DHARs) and Tetrachlorohydroquinone dehalogenase (TCHQD). While GSTs show overall sequence diversification within and between classes, they retain a high level of three-dimensional structure conservation over long evolutionary periods. In this review mainly the soluble plant GSTs will be considered by giving attention to their structures, subcellular localizations, genomic organizations, catalytic/noncatalytic functions, and comparisons given with respect to their mammalian counterparts where necessary.

Pivato M., Fabrega-Prats M., Masi A. Low-molecular-weight thiols in plants: Functional and analytical implications // Archives of Biochemistry and Biophysics. 2014. Vol. 560. P. 83–99.

Low-molecular-weight (LMW) thiols are a class of highly reactive compounds massively involved in the maintenance of cellular redox homeostasis. They are implicated in plant responses to almost all stress factors, as well as in the regulation of cellular metabolism. The most studied LMW thiols are glutathione and its biosynthetically related compounds (cysteine, gamma-glutamylcysteine, cysteinylglycine, and phytochelatins). Other LMW thiols are described in the literature, such as thiocysteine, cysteamine, homocysteine, lipoic acid, and many species-specific volatile thiols. Here, we review the known LMW thiols in plants, briefly describing their physico-chemical properties, their relevance in post-translational protein modification, and recently-developed thiol detection methods. Current research points to a huge thiol biodiversity in plants and many species-specific and organ-specific thiols remain to be identified. Recent advances in technology should help researchers in this very challenging task, helping us to decipher the roles of thiols in plant metabolism.

Polacco J.C., Mazzafera P., Tezotto T. Opinion - Nickel and urease in plants: Still many knowledge gaps // Plant Science. 2013. Vol. 199. P. 79–90.

We propose experimental strategies to expand our understanding of the role of Ni in plants, beyond the Ni-metallocenter of urease, still the only identified Ni-containing plant enzyme. While Ni has been considered an essential mineral for plants there is a clear lack of knowledge of its involvement in metabolic steps except the urease-catalyzed conversion of urea to ammonia and bicarbonate. We argue that urease (and hence, Ni) plays an important role in optimal N-use efficiency under various N regimes by recycling urea-N, which is generated endogenously exclusively from arginase action on arginine. We further suggest that urease and arginase may connect different metabolic compartments under stress situations, and therefore may be involved in stress tolerance. To determine possible non-urease roles of Ni we call for experimental manipulation of both Ni and N availability in urease-negative mutants. Plant ureases have been shown to have defense roles, distinct from their ureolytic activity, and we call for investigation of whether Ni helps maintain a urease conformation or stability for these non-ureolytic defense roles. The beneficial effects of Ni at upper concentration limits have not been fully examined. We posit a "Ni strategy" of plants whose growth/performance is stimulated by unusual amounts of soil Ni, for defense and/or for maximal N-use efficiency. While we know little about Ni and urease roles in N metabolism and defense, virtually nothing is known about Ni roles in plant-microbial 'consortia.' And, much of what we know of Ni and urease is limited to only a few plants, e.g. soybean, potato and Arabidopsis, and we suggest studies vigorously extended to other plants.

Qiu B. et al. Alleviation of chromium toxicity in rice seedlings by applying exogenous glutathione // Journal of Plant Physiology. 2013. Vol. 170, № 8. P. 772–779.

The effect of exogenous reduced glutathione (GSH) on alleviation of hexavalent chromium (Cr6+) toxicity to rice seedlings and its physiological mechanisms were comprehensively investigated in a series of experiments. Our results showed that growth and nutrient uptake of rice seedlings were dramatically reduced under 100 mu M Cr6+ stress, and the reduction was significantly alleviated by exogenous GSH. Cr6+ stress also reduced cell viability in root tips and damaged ultrastructure of both chloroplasts and root cells, while the addition of GSH alleviates those negative effects. Cr-induced toxicity and GSH-caused Cr alleviation differed significantly between Cr-tolerant Line 117 (L117) and Cr-sensitive Line 41 (L41). Under Cr6+ stress, cystine content was increased and GSH content was decreased in rice plants, exogenous GSH, however, mitigated the Cr-toxicity by reversing the Cr-induced changes of the two compounds. The types of Cr-induced secretion of organic acids varied between the genotypes, where reduction in the contents of acetic and lactic acids and tartaric and malic acids were observed in L117 and L41, respectively. The addition of GSH alleviated the reduction of secretion of these organic acids. Exogenous GSH also altered the forms of Cr ions in the rhizosphere and the fraction of distribution at subcellular level in both shoots and roots. It may be concluded that the alleviation of Cr6+ toxicity by exogenous GSH is directly attributed to its regulation on forms of Cr ions in rhizosphere and their distribution at subcellular levels.

Ramakrishna B., Rao S.S.R. Foliar application of brassinosteroids alleviates adverse effects of zinc toxicity in radish (Raphanus sativus L.) plants // Protoplasma. 2015. Vol. 252, № 2. P. 665–677.

Growth chamber experiments were conducted to investigate the comparative effect of 24-epibrassinolide (EBL) and 28-homobrassinolide (HBL) at 0.5, 1.0, or 2.0 mu M concentrations by foliar application on radish plants growing under Zn2+ stress. In radish plants exposed to excess Zn2+, growth was substantially reduced in terms of shoot and root length, fresh and dry weight. However, foliar application of brassinosteroids (BRs) was able to alleviate Zn2+-induced stress and significantly improve the above growth traits. Zinc stress decreased chlorophyll a, b, and carotenoids levels in radish plants. However, follow-up treatment with BRs increased the photosynthetic pigments in stressed and stress-free plants. The treatment of BRs led to reduced levels of H2O2, lipid peroxidation and, electrolyte leakage (ELP) and improved the leaf relative water content (RWC) in stressed plants. Increased levels of carbonyls indicating enhanced protein oxidation under Zn2+ stress was effectively countered by supplementation of BRs. Under Zn2+ stress, the activities of catalase (CAT), ascorbate peroxidase (APX), and superoxidase dismutase (SOD) were increased but peroxidase (POD) and glutathione reductase (GR) decreased. Foliar spraying of BRs enhanced all these enzymatic activities in radish plants under Zn2+ stress. The BRs application greatly enhanced contents of ascorbate (ASA), glutathione (GSH), and proline under Zn2+ stress. The decrease in the activity of nitrate reductase (NR) caused by Zn2+ stress was restored to the level of control by application of BRs. These results point out that BRs application elevated levels of antioxidative enzymes as well as antioxidants could have conferred resistance to radish plants against Zn2+ stress resulting in improved plant growth, relative water content and photosynthetic attributes. Of the two BRs, EBL was most effective in amelioration of Zn2+ stress.

Rojas-Loria C.C. et al. Role of glutathione and glutathione S-transferase in lead tolerance and bioaccumulation by Dodonaea viscosa (L.) Jacq // Acta Physiologiae Plantarum. 2014. Vol. 36, № 9. P. 2501–2510.

Glutathione (GSH) plays a central role in the plant tolerance against the toxic effects of metals. It is a key antioxidant and acts as a cofactor for glutathione S-transferase (GST). The main objective of this study was to determine the Pb tolerance and bioaccumulation by Dodonaea viscosa (L.) Jacq. and their relation to GSH production and GST activity. The relationship between the Pb tolerance and bioaccumulation by D. viscosa and the effect of the exposure time on the GSH production or the GST activity was assessed in trials with perlite under different Pb treatments. D. viscosa showed a remarkable tolerance to Pb [half-inhibitory concentration (IC50) = 2,797 mg kg(-1)] and accumulated up to 11,428 mg Pb kg(-1) in dry roots with a limited translocation to shoots without any signs of phytotoxicity after 105 days of exposure. The stress caused by the fast Pb uptake rate (489 mg kg(-1) day(-1)) during the first 10 days of exposure was strongly correlated to increased GSH contents (similar to 1.3-fold) and GST activities (similar to 3.6-fold) in both shoots and roots. The results indicate that the Pb stress triggered a defense mechanism that involved increased contents of GSH and GST activities, suggesting that both variables are involved in the tolerance of D. viscosa against Pb toxicity.

Shanmugam V., Tsednee M., Yeh K.-C. ZINC TOLERANCE INDUCED BY IRON 1 reveals the importance of glutathione in the cross-homeostasis between zinc and iron in Arabidopsis thaliana // Plant Journal. 2012. Vol. 69, № 6. P. 1006–1017.

Zinc is an essential micronutrient for plants, but it is toxic in excess concentrations. In Arabidopsis, additional iron (Fe) can increase Zn tolerance. We isolated a mutant, zinc tolerance induced by iron 1, designated zir1, with a defect in Fe-mediated Zn tolerance. Using map-based cloning and genetic complementation, we identified that zir1 has a mutation of glutamate to lysine at position 385 on ?-glutamylcysteine synthetase (GSH1), the enzyme involved in glutathione biosynthesis. The zir1 mutant contains only 15% of the wild-type glutathione level. Blocking glutathione biosynthesis in wild-type plants by a specific inhibitor of GSH1, buthionine sulfoximine, resulted in loss of Fe-mediated Zn tolerance, which provides further evidence that glutathione plays an essential role in Fe-mediated Zn tolerance. Two glutathione-deficient mutant alleles of GSH1, pad2-1 and cad2-1, which contain 22% and 39%, respectively, of the wild-type glutathione level, revealed that a minimal glutathione level between 22 and 39% of the wild-type level is required for Fe-mediated Zn tolerance. Under excess Zn and Fe, the recovery of shoot Fe contents in pad2-1 and cad2-1 was lower than that of the wild type. However, the phytochelatin-deficient mutant cad1-3 showed normal Fe-mediated Zn tolerance. These results indicate a specific role of glutathione in Fe-mediated Zn tolerance. The induced accumulation of glutathione in response to excess Zn and Fe suggests that glutathione plays a specific role in Fe-mediated Zn tolerance in Arabidopsis. We conclude that glutathione is required for the cross-homeostasis between Zn and Fe in Arabidopsis.

Sharma S.S., Dietz K.J. The significance of amino acids and amino acid-derived molecules in plant responses and adaptation to heavy metal stress // Journal of Experimental Botany. 2006. Vol. 57, № 4. P. 711–726.

Plants exposed to heavy metals accumulate an array of metabolites, some to high millimolar concentrations. This review deals with N-containing metabolites frequently preferentially synthesized under heavy metal stress such as Cd, Cu, Ni, and Zn. Special focus is given to proline, but certain other amino acids and oligopeptides, as well as betaine, polyamines, and nicotianamine are also addressed. Particularly for proline a large body of data suggests significant beneficial functions under metal stress. In general, the molecules have three major functions, namely metal binding, antioxidant defence, and signalling. Strong correlative and mechanistic experimental evidence, including work with transgenic plants and algae, has been provided that indicates the involvement of metal-induced proline in metal stress defence. Histidine, other amino acids and particularly phytochelatins and glutathione play a role in metal binding, while polyamines function as signalling molecules and antioxidants. Their accumulation needs to be considered as active response and not as consequence of metabolic dys-regulation.

Soudek P. et al. Effect of Heavy Metals on Inhibition of Root Elongation in 23 Cultivars of Flax (Linum usitatissimum L.) // Archives of Environmental Contamination and Toxicology. 2010. Vol. 59, № 2. P. 194–203.

The effect of toxic metals on seed germination was studied in 23 cultivars of flax (Linum usitatissimum L.). Toxicity of cadmium, cobalt, copper, zinc, nickel, lead, chromium, and arsenic at five different concentrations (0.01-1 mM) was tested by standard ecotoxicity test. Root length was measured after 72 h of incubation. Elongation inhibition, EC50 value, slope, and NOEC values were calculated. Results were evaluated by principal component analysis, a multidimensional statistical method. The results showed that heavy-metal toxicity decreased in the following order: As3+ a parts per thousand yen As5+ > Cu2+ > Cd2+ > Co2+ > Cr6+ > Ni2+ > Pb2+ > Cr3+ > Zn2+.

Srivastava M. et al. Effects of selenium on arsenic uptake in arsenic hyperaccumulator Pteris vittata L. // Bioresource Technology. 2009. Vol. 100, № 3. P. 1115–1121.

Selenium (Se) is a non-metallic element, which has the capability to increase the antioxidative capacity and stress tolerance of plants to heavy metals. Plants vary considerably in their physiological response to Se. The reported research investigated the effects of Se on arsenic (As) uptake by As hyperaccumulator Pteris vittata L. and determined possible mechanisms of interaction. Pteris vittata plants were exposed hydroponically to 0, 150 or 300 ?M of Na2HAsO4 in the presence of 0, 5 or 10 ?M of Na2SeO4 for 5 or 10 d. Application of 5 ?M Se enhanced As concentration by P. vittata fronds by 7–45%. At 5 ?M, Se acted as an antioxidant, inhibiting lipid peroxidation (reduced by 26–42% in the fronds) via increased levels of thiols and glutathione (increased by 24% in the fronds). The results suggest that Se is either an antioxidant or it activates plant protective mechanisms, thereby alleviating oxidative stress and improving arsenic uptake in P. vittata.

Srivastava R.K. et al. Cadmium and lead interactive effects on oxidative stress and antioxidative responses in rice seedlings // Protoplasma. 2014. Vol. 251, № 5. P. 1047–1065.

Interactive effects of two heavy metal pollutants Cd and Pb in the growth medium were examined on their uptake, production of reactive oxygen species (ROS), induction of oxidative stress and antioxidative defence responses in Indica rice (Oryza sativa L.) seedlings. When rice seedlings in sand culture were exposed to 150 mu M Cd (NO3)(2) or 600 mu M Pb (CH3COO)(2) individually or in combination for 8-16 days, a significant reduction in root/shoot length, fresh weight, relative water content, photosynthetic pigments and increased production of ROS (O2E (TM)(-) and H2O2) was observed. Both Cd and Pb were readily taken up by rice roots and localisation of absorbed metals was greater in roots than in shoots. When present together in the growth medium, uptake of both the metals Cd and Pb declined by 25-40 %. Scanning electron microscope (SEM) imaging of leaf stomata revealed that Pb caused more distortion in the shape of guard cells than Cd. Dithizone staining of roots showed localisation of absorbed Cd on root hairs and epidermal cells. Both Cd and Pb caused increased lipid peroxidation, protein carbonylation, decline in protein thiol and increase in non-protein thiol. The level of reduced forms of non-enzymic antioxidants glutathione (GSH) and ascorbate (AsA) and their redox ratios (GSH/AsA) declined, whereas the activities of antioxidative enzymes superoxide dismutase (SOD) and guaiacol peroxidase (GPX) increased in metal treated seedlings compared to controls. In-gel activity staining also revealed increased intensities of SOD and GPX isoforms with metal treatments. Catalase (CAT) activity increased during early days (8 days) of metal exposure and declined by 16 days. Results suggest that oxidative stress is an important component in expression of Cd and Pb toxicities in rice, though uptake of both metals gets reduced considerably when present together in the medium.

Srivastava S., Dubey R.S. Nitric oxide alleviates manganese toxicity by preventing oxidative stress in excised rice leaves // Acta Physiologiae Plantarum. 2012. Vol. 34, № 2. P. 819–825.

In the present study, we have investigated the effects of nitric oxide (NO) on alleviating manganese (Mn)-induced oxidative stress in rice leaves. Exogenous MnCl2 treatment to excised rice leaves for 24 and 48 h resulted in increased production of H2O2 and lipid peroxides, decline in the levels of antioxidants, glutathione and ascorbic acid, and increased activities of antioxidative enzymes, superoxide dismutase, guaiacol peroxidase, catalase, ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase. Treatment of rice leaves with 100 mu M sodium nitroprusside (SNP), a NO donor, was effective in reducing Mn-induced increased levels of H2O2, lipid peroxides and increased activities of antioxidative enzymes. The levels of reduced ascorbate and glutathione were considerably recovered due to SNP treatment. The effect of SNP was reversed by the addition of NO scavenger, 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (c-PTIO) suggesting that ameliorating effect of SNP is due to release of NO. The results indicate that MnCl2 induces oxidative stress in excised rice leaves, lowers the levels of reduced ascorbate and glutathione, and elevates activities of the key antioxidative enzymes. NO appears to provide a protection to the rice leaves against Mn-induced oxidative stress and that exogenous NO application could be advantageous in combating the deleterious effects of Mn-toxicity in rice plants.

Szarka A., Tomasskovics B., Banhegyi G. The Ascorbate-glutathione-?-tocopherol Triad in Abiotic Stress Response // International Journal of Molecular Sciences. 2012. Vol. 13, № 4. P. 4458–4483.

The life of any living organism can be defined as a hurdle due to different kind of stresses. As with all living organisms, plants are exposed to various abiotic stresses, such as drought, salinity, extreme temperatures and chemical toxicity. These primary stresses are often interconnected, and lead to the overproduction of reactive oxygen species (ROS) in plants, which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA, which ultimately results in oxidative stress. Stress-induced ROS accumulation is counteracted by enzymatic antioxidant systems and non-enzymatic low molecular weight metabolites, such as ascorbate, glutathione and ?-tocopherol. The above mentioned low molecular weight antioxidants are also capable of chelating metal ions, reducing thus their catalytic activity to form ROS and also scavenge them. Hence, in plant cells, this triad of low molecular weight antioxidants (ascorbate, glutathione and ?-tocopherol) form an important part of abiotic stress response. In this work we are presenting a review of abiotic stress responses connected to these antioxidants.

Taylor A.F. et al. Investigating the Toxicity, Uptake, Nanoparticle Formation and Genetic Response of Plants to Gold // Plos One. 2014. Vol. 9, № 4. P. e93793.

We have studied the physiological and genetic responses of Arabidopsis thaliana L. (Arabidopsis) to gold. The root lengths of Arabidopsis seedlings grown on nutrient agar plates containing 100 mg/L gold were reduced by 75%. Oxidized gold was subsequently found in roots and shoots of these plants, but gold nanoparticles (reduced gold) were only observed in the root tissues. We used a microarray-based study to monitor the expression of candidate genes involved in metal uptake and transport in Arabidopsis upon gold exposure. There was up-regulation of genes involved in plant stress response such as glutathione transferases, cytochromes P450, glucosyl transferases and peroxidases. In parallel, our data show the significant down-regulation of a discreet number of genes encoding proteins involved in the transport of copper, cadmium, iron and nickel ions, along with aquaporins, which bind to gold. We used Medicago sativa L. (alfalfa) to study nanoparticle uptake from hydroponic culture using ionic gold as a non-nanoparticle control and concluded that nanoparticles between 5 and 100 nm in diameter are not directly accumulated by plants. Gold nanoparticles were only observed in plants exposed to ionic gold in solution. Together, we believe our results imply that gold is taken up by the plant predominantly as an ionic form, and that plants respond to gold exposure by up-regulating genes for plant stress and down-regulating specific metal transporters to reduce gold uptake.

Thao N.P. et al. Role of Ethylene and Its Cross Talk with Other Signaling Molecules in Plant Responses to Heavy Metal Stress // Plant Physiology. 2015. Vol. 169, № 1. P. 73–84.

Excessive heavy metals (HMs) in agricultural lands cause toxicities to plants, resulting in declines in crop productivity. Recent advances in ethylene biology research have established that ethylene is not only responsible for many important physiological activities in plants but also plays a pivotal role in HM stress tolerance. The manipulation of ethylene in plants to cope with HM stress through various approaches targeting either ethylene biosynthesis or the ethylene signaling pathway has brought promising outcomes. This review covers ethylene production and signal transduction in plant responses to HM stress, cross talk between ethylene and other signaling molecules under adverse HM stress conditions, and approaches to modify ethylene action to improve HM tolerance. From our current understanding about ethylene and its regulatory activities, it is believed that the optimization of endogenous ethylene levels in plants under HM stress would pave the way for developing transgenic crops with improved HM tolerance.

Thounaojam T.C. et al. Excess copper induced oxidative stress and response of antioxidants in rice // Plant Physiology and Biochemistry. 2012. Vol. 53. P. 33–39.

To investigate the effects of copper (Cu), rice plant (Oryza sativa. L. var. MSE-9) was treated with different Cu concentrations (0, 10, 50 and 100 mu M) for 5 days in hydroponic condition. Gradual decrease in shoot and root growth was observed with the increase of Cu concentration and duration of treatment where maximum inhibition was recorded in root growth. Cu was readily absorbed by the plant though the maximum accumulation was found in root than shoot. Hydrogen peroxide (H2O2) production and lipid peroxidation were found increased with the elevated Cu concentration indicating excess Cu induced oxidative stress. Antioxidant enzymes superoxide dismutase (SOD), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) and glutathione reductase (GR) were effectively generated at the elevated concentrations of Cu though catalase (CAT) did not show significant variation with respect to control. Ascorbate (ASH), glutathione (GSH) and proline contents were also increased in all the Cu treated plants compared with the control. SOD isoenzyme was greatly affected by higher concentration of Cu and it was consistent with the changes of the activity assayed in solution. The present study confirmed that excess Cu inhibits growth, induced oxidative stress by inducing ROS formation while the stimulated antioxidative system appears adaptive response of rice plant against Cu induced oxidative stress. Moreover proline accumulation in Cu stress plant seems to provide additional defense against the oxidative stress.

Tran T.A., Popova L.P. Functions and toxicity of cadmium in plants: recent advances and future prospects // Turkish Journal of Botany. 2013. Vol. 37, № 1. P. 1–13.

Heavy metals are important environmental pollutants and their toxicity is a problem of increasing significance for ecological, evolutionary, nutritional, and environmental reasons. Of all non-essential heavy metals, cadmium (Cd) is perhaps the metal that has attracted the most attention in soil science and plant nutrition due to its potential toxicity to humans, and also its relative mobility in the soil plant system. This review emphasises Cd toxicity on plants with regards to ecological, physiological, and biochemical aspects. It summarises the toxic symptoms of Cd in plants (i.e. growth and plant development, alterations in photosynthesis, stomatal regulation, enzymatic activities, water relation, mineral uptake, protein metabolism, membrane functioning, etc.). The main barriers against Cd entrance to the cell, as well as some aspects related to phytochelatine-base sequestration and compartmentalisation processes, are also reviewed. Cd-induced oxidative stress is also considered one of the most widely studied topic in this review. This review may help in interdisciplinary studies to assess the ecological significance of Cd stress.

Upadhyay R.K. Metal stress in plants: its detoxification in natural environment // Brazilian Journal of Botany. 2014. Vol. 37, № 4. P. 377–382.

In natural environment, plants consist of both metabolic and tolerant mechanisms in toxic non-essential metals like Arsenic, Cadmium, Lead and Mercury. Natural activities composed of mining and smelting operations, including some haphazard practices in agriculture, have extensively contaminated some areas around the world-as for instances, in India, Japan, Indonesia and China by Cadmium, Copper and Arsenic and Copper and Lead in Greece. In fact, South-East Asia is suffering from the contamination of the groundwater Arsenic, as in the same way the existence of Copper, Lead, Nickel, Zinc and Cadmium is nothing new in some parts of Australia. Indeed, heavy metal contamination has become a worldwide problem. The uptake as well as accumulation of the aforesaid metals by plants is the main factor responsible for threatening the health of both man and animal into their food by toxic metals. The production of phytochelatins, a metal-binding thiol peptide and metallothionin, to react against the heavy metal stress may have provided for an appropriate metal tolerance in plants but needs a comprehensive study on it; for a better understanding on the different metal transports, their accumulations as well as over expressions in plants would definitely pave the better ways to develop metal tolerant plants or transgenics. Keeping the rising concerns over heavy metal stress affecting agriculture produce and plants in view in water; this review aims at throwing light as a tip on the iceberg about the physiological and biochemical mechanisms of metal accumulations, their responses and detoxification to the toxicity as well as to the metal stress tolerant plants.

Van Hoewyk D. A tale of two toxicities: malformed selenoproteins and oxidative stress both contribute to selenium stress in plants // Annals of Botany. 2013. Vol. 112, № 6. P. 965–972.

Despite seleniums toxicity in plants at higher levels, crops supply most of the essential dietary selenium in humans. In plants, inorganic selenium can be assimilated into selenocysteine, which can replace cysteine in proteins. Selenium toxicity in plants has been attributed to the formation of non-specific selenoproteins. However, this paradigm can be challenged now that there is increasingly abundant evidence suggesting that selenium-induced oxidative stress also contributes to toxicity in plants. This Botanical Briefing summarizes the evidence indicating that selenium toxicity in plants is attributable to both the accumulation of non-specific selenoproteins and selenium-induced oxidative stress. Evidence is also presented to substantiate the claim that inadvertent selenocysteine replacement probably impairs or misfolds proteins, which supports the malformed selenoprotein hypothesis. The possible physiological ramifications of selenoproteins and selenium-induced oxidative stress are discussed. Malformed selenoproteins and oxidative stress are two distinct types of stress that drive selenium toxicity in plants and could impact cellular processes in plants that have yet to be thoroughly explored. Although challenging, deciphering whether the extent of selenium toxicity in plants is imparted by selenoproteins or oxidative stress could be helpful in the development of crops with fortified levels of selenium.

Vinterhalter B., Vinterhalter D. Nickel hyperaccumulation in shoot cultures of Alyssum markgrafii // Biologia Plantarum. 2005. Vol. 49, № 1. P. 121–124.

Shoot cultures of Alyssum markgrafii O.E. Shulz, endemic nickel hyperaccumulating species of central Balkan, were established and maintained on Murashige and Skoog medium supplemented with 0.2 mg dm(-3) benzyladenine (BA). Nickel in form of NiCl2 . 6 H2O was supplemented at 22 different concentrations ranging from 0.0001 to 15 mM but none of them was lethal to cultures. High Ni2+ concentrations (10 mM or more) arrested shoot growth which, upon transfer to Ni-free medium, commenced via axillary bud proliferation. Shoots that developed from axillary buds through the subculture manifested increased tolerance to Ni2+ expressed as shoot elongation. Shoot multiplication and dry biomass production decreased with increase of Ni2+ in medium. Only the accumulation of Ni2+ in tissues increased with Ni2+ content of the medium. Apart from shoot cultures, high Ni2+ accumulation was registered in undifferentiated callus cultured on medium with 0.5 mg dm?3 BA and 0.5 mg dm?3 naphthylacetic acid. Highest content of accumulated Ni was 2.37 ?g g?1 (d.m.) in shoots and 2.65 ?g g?1 (d.m.) in callus, both measured on medium with 15 mM Ni2+.

Wang H. et al. Up-regulation of chloroplastic antioxidant capacity is involved in alleviation of nickel toxicity of Zea mays L. by exogenous salicylic acid // Ecotoxicology and Environmental Safety. 2009. Vol. 72, № 5. P. 1354–1362.

A pot experiment was carried out to investigate the effect of exogenous salicylic acid (SA) on the growth, photosynthesis, oxidative stress and responses of chloroplastic antioxidant defense system of maize (Zea mays L.) plants grown in a nickel (Ni)-contaminated soil. The results indicate that exogenous SA significantly decreased the reduction in dry weight, chlorophyll and P-carotene contents, and net photosynthetic rate of the Ni-stressed maize, demonstrating an alleviating effect of SA on Ni toxicity of plants. Superoxide anion generation rate, H2O2 and malondialdehyde (MDA) contents, and lipoxygenase (LOX, EC activity significantly increased in the chloroplasts of maize exposed to Ni stress, revealing an oxidative damage occurred in maize chloroplasts, whereas, the values of these parameters were markedly lowered in the SA-treated plants under Ni stress. Application of SA significantly enhanced the activities of superoxide dismutase (SOD, EC, ascorbate peroxidase (APX, EC, monodehydroascorbate reductase (MDHAR, EC, dehydroascorbate reductase (DHAR, EC and glutathione reductase (GR, EC, and the poll of reduced ascorbate and glutathione in chloroplasts of the Ni-stressed maize. Accordingly, the fact that SA up-regulates the capacity of antioxidant defense system in chloroplasts, thus reducing the oxidative damage, is involved in the SA-induced alleviation of Ni toxicity in maize.

Wani P.A., Khan S., Zaidi A. Effect of metal-tolerant plant growth-promoting Rhizobium on the performance of pea grown in metal-amended soil // Archives of Environmental Contamination and Toxicology. 2008. Vol. 55, № 1. P. 33–42.

The nickel- and zinc-tolerant plant growth-promoting (PGP) Rhizobium sp. RP5 was isolated from nodules of pea, grown in metal-contaminated Indian soils. The PGP potentials of strain RP5 was assessed under in vitro conditions. Strain RP5 displayed a high level of tolerance to nickel (350 mu g ml(-1)) and zinc (1500 mu g ml(-1)) and showed PGP activity under in vitro conditions. The PGP activity of this strain was further assessed with increasing concentrations of nickel and zinc, using pea as a test crop. The bio-inoculant enhanced the dry matter, nodule numbers, root N, shoot N, leghemoglobin, seed yield, and grain protein (GP) by 19%, 23%, 26%, 47%, 112%, 26%, and 8%, respectively, at 290 mg Ni kg(-1) while at 4890 mg Zn kg(-1) soil, it increased the dry matter, nodule numbers, leghemoglobin, seed yield, GP, and root and shoot N by 18%, 23%, 78%, 26%, 7%, 25%, and 42%, respectively, compared to plants grown in soil amended with metal only. The bio-inoculant increased the glutathione reductase activity of roots and nodules by 46% and 65% at 580 mg Ni kg(-1) and 47% and 54% at 9780 mg Zn kg(-1) soil, respectively, compared to uninoculated plants. The inoculated strain decreased the concentration of nickel and zinc in plant organs. The intrinsic abilities of nitrogen fixation, growth promotion, and the ability to reduce the toxicity of nickel and zinc of the tested strain could be of practical importance in augmenting the growth and yield of pea, in nickel- and zinc-polluted soils.

Yadav S.K. Heavy metals toxicity in plants: An overview on the role of glutathione and phytochelatins in heavy metal stress tolerance of plants // South African Journal of Botany. 2010. Vol. 76, № 2. P. 167–179.

Plants experience oxidative stress upon exposure to heavy metals that leads to cellular damage. In addition, plants accumulate metal ions that disturb cellular ionic homeostasis. To minimize the detrimental effects of heavy metal exposure and their accumulation, plants have evolved detoxification mechanisms. Such mechanisms are mainly based on chelation and subcellular compartmentalization. Chelation of heavy metals is a ubiquitous detoxification strategy described in wide variety of plants. A principal class of heavy metal chelator known in plants is phytochelatins (PCs), a family of Cys-rich peptides. PCs are synthesized non-translationally from reduced glutathione (GSH) in a transpeptidation reaction catalyzed by the enzyme phytochelatin synthase (PCS). Therefore, availability of glutathione is very essential for PCs synthesis in plants at least during their exposure to heavy metals. Here, I reviewed on effect of heavy metals exposure to plants and role of GSH and PCs in heavy metal stress tolerance. Further, genetic manipulations of GSH and PCs levels that help plants to ameliorate toxic effects of heavy metals have been presented.

Yusuf M. et al. Nickel: An Overview of Uptake, Essentiality and Toxicity in Plants // Bulletin of Environmental Contamination and Toxicology. 2011. Vol. 86, № 1. P. 1–17.

Nickel even though recognized as a trace element, its metabolism is very decisive for certain enzyme activities, maintaining proper cellular redox state and various other biochemical, physiological and growth responses. Study of the aspects related with uptake, transport and distributive localization of Ni is very important in various cellular metabolic processes particularly under increased nitrogen metabolism. This review article, in core, encompasses the dual behavior of Ni in plants emphasizing its systemic partitioning, essentiality and ill effects. However, the core mechanism of molecules involved and the successive physiological conditions required starting from the soil absorption, neutralization and toxicity generated is still elusive, and varies among the plants.

Абрамов А.Ф., Слепцова Т.В. Биоиндикация загрязнения окружающей среды тяжелыми металлами по содержанию их в листьях берёзы обыкновенной (Betula alba L.) в Якутии // Вестник ИрГСХА. 2015. № 69. С. 31-36.

Приведены результаты исследований уровня загрязнения окружающей среды Pb, Hg, Cd в г. Якутске и Кобяйском районе Республики Саха (Якутия) по содержанию их в листьях берёзы обыкновенной. Отмечено, что содержание Pb, Hg, Cd в листьях берёзы имеет прямую связь с уровнем загрязнения территории города. В листьях берёз, растущих на естественном грунте квартала 69 (Сайсар), содержание Pb превышает ПДК в 1.6 раз, Hg - в 12.0 раз, Cd - в 6.5 раз, а в квартале 31 (Рабочий городок), соответственно, Pb - в 1.4 раза, Hg - в 11.0 раз, Cd - в 5.0 раз. В центре города в листьях берёзы (проспект Ленина) на привозном грунте с берeзовой рощи Вилюйского тракта содержание Pb, Hg, Cd оказалось меньше, чем в 31, 69 кварталах г. Якутска. В Кобяйском районе в листьях берeз, собранных с участков Ситтэ, содержание Pb превышает ПДК в 1.5 раза, Hg - 18.0 раз, Cd - в 1.9 раза, а на участке Куокуй, соответственно, Pb - 1.2 раза, Hg - в 16.0 раз, Cd - в 1.4 раз. Содержание Pb, Hg, Cd в листьях берeзы на участках Турбаахы и Сангар было меньше, чем на участках Ситтэ и Куокуй.

Автухович И.Е., Постников Д.А. Влияние ЭДТА на поведение металлов в субстрате и их накопление растениями // Естественные и технические науки. 2014. № 1 (69). С. 50-54.

Хелатообразующий агент ЭДТА был внесен в субстрат, составленный на основе осадков сточных вод (ОСВ), под растения (Carthamus tinctorius L.). Выявлено, что ЭДТА имеет высокую стабильность в ОСВ субстрате, повышает биодоступность меди и цинка и их накопление растениями. В конце эксперимента зарегистрировано явление антагонизма между ионами цинка и меди, вероятно вследствие частичного разрушения металл-ЭДТА комплексов.

Андреева И.В., Говорина В.В. К Вопросу о возможных причинах высокой подвижности никеля в растениях // Агрохимия. 2008. № 6. С. 68-71.

Обсуждаются результаты вегетационного опыта в водной культуре по определению характера компартментации никеля в растениях фасоли и овса при нетоксичной дозе никеля в питательном растворе. Установлено, что данный элемент локализован преимущественно в протопласте в растворимой форме, что частично объясняет его высокую подвижность в растениях.

Башмакова Е.Б., Пашковский П.П. и др. Возможные механизмы развития дефицита железа у растений мимулюса крапчатого в условиях совместного действия солей никеля и цинка // Физиология растений. 2015. Т. 62. № 6. С. 814-826.

Исследованы возможные причины развития дефицита железа у растений Mimulus guttatus Fischer ex DC., подвергнутых раздельному или совместному воздействию NiSO4 (20 и 80 мкМ) и ZnSO4 (50, 100 и 200 мкМ). Растения в возрасте 6 нед. выращивали в течение последующих 28 суток в условиях фитотрона в водной культуре на модифицированной среде Роризона в присутствии или в отсутствие в культуральной среде солей NiSO4 и/или ZnSO4. Установили, что растения M. guttatus обладают высокой устойчивостью к совместному действию сульфатов никеля и цинка. Обнаружен антагонизм между ионами Ni2+ и Zn2+ при поглощении корнями: ионы Zn2+ препятствовали поступлению ионов Ni2+ в корни, даже если в среде концентрация ионов Zn2+ была меньше концентрации ионов Ni2+ в 1.6 раза, тогда как ионы Ni2+ ингибировали поглощение ионов Zn2+ корнями, если в среде концентрация ионов Ni2+ в 1.6 раза превосходила концентрацию ионов Zn2+. Никель не влиял на поступление цинка в надземные органы, тогда как цинк способствовал усилению транслокации никеля из корней в листья. Продемонстрирована строгая обратная корреляция между содержанием железа и суммарным содержанием цинка и никеля в листьях, а также обратная корреляция между транслокацией железа и транслокацией никеля. Анализ содержания железа и активности Fe(III)-хелатредуктазы в корнях показал, что развитие дефицита железа в растениях в присутствии NiSO4 и ZnSO4 не является результатом ингибирования ионами Ni2+ и Zn2+ поступления ионов Fe2+ в корни. Обнаружено, что растения отвечали на воздействия 50?200 мкМ ZnSO4 многократным увеличением содержания свободного никотианамина (НА) в корневой системе, тогда как при добавлении в культуральную среду, помимо ZnSO4, 20 или 80 мкМ NiSO4 в корнях происходило по меньшей мере 3-кратное снижение уровня свободного НА относительно уровня свободного НА в корнях при воздействии ZnSO4. Наконец, установлена прямая корреляция между содержанием свободного НА и аккумуляцией никеля в листьях растений. Полученные данные свидетельствуют о том, что в основе развития дефицита железа в растениях M. guttatus, подвергнутых совместному воздействию сульфатов никеля и цинка, лежит конкуренция между ионами Ni2+ и Fe2+/Fe3+ за хелатор, которым, по-видимому, является НА.

Бородина Н.А. Аккумуляция тяжелых металлов хвоей сосны в урбоэкосистеме города Благовещенска // Известия Самарского научного центра Российской академии наук. 2012. Т. 14. № 1-8. С. 1958-1962.

Исследовано аэрогенное загрязнение хвои сосны (Pinus silvestris) тяжелыми металлами в урбоэкосистеме г. Благовещенска. Выявлены особенности накопления Cu, Zn, Mn, Cr, Ni, Co, Pb и Mn в хвое сосны в зависимости от степени техногенного загрязнения.

Гамбарова Н.Г., Гинс В.К. Влияние экзогенного пероксида водорода на антиоксидантную систему хлоропластов у пшеницы // Сельскохозяйственная биология. 2012. № 3. С. 75-79.

У термоустойчивого сорта пшеницы Шарг изучали активность супероксидисмутазы (СОД), глутатионредуктазы (ГР) и глутатионтрансферазы (ГТ) в хлоропластах из 14-суточных проростков в присутствии разных концентраций (1 мМ и 10 мМ) экзогенного пероксида водорода Н 2О 2. Выявлена индукция активности ГР на начальном этапе окислительного стресса. Показано усиление активности СОД и ГТ в условиях, исключающих возможность их синтеза, что обусловливает дополнительную защиту пластид в ранние сроки действия экстремальных факторов.

Гладков Е.А., Гладкова О.Н., Глушецкая Л.С. Оценка устойчивости к тяжелым металлам полевицы побегоносной (Agrostis Stolonifera), полученной в результате клеточной селекции на устойчивость к этим контаминантам, во втором поколении и ее способности к аккумуляции этих веществ // Биотехнология. 2010. № 5. 76-80.

Из семян полевицы побегоносной, полученных от растений, подвергшихся клеточной селекции на устойчивость к тяжелым металлам и NaCl, выращивали растения и оценивали чувствительность семян и растений к содержащимся в почве кадмию, меди, цинку и свинцу. Полученные данные указывают на сохранение толерантности к исследованным экологическим факторам у семян растений второго поколения. В ряде случаев наблюдалась перекрестная устойчивость к загрязняющим факторам. Полученные растения можно рекомендовать для использования с целью очистки почвы от тяжелых металлов в городских экосистемах.

Иванов Ю.В., Савочкин Ю.В., Кузнецов В.В. Сосна обыкновенная как модельный объект для изучения механизмов адаптации хвойных к действию тяжелых металлов. 1. Изменение морфометрических и физиологических параметров при развитии сеянцев сосны в условиях хронического действия цинка // Физиология растений. 2011. Т. 58. № 5. С. 728-736.

Исследовали действие цинка (50?150 мкМ ZnSO4) на посевные качества семян, морфометрические и физиологические параметры развития сеянцев сосны обыкновенной (Pinus sylvestris L.) в течение первых 6 нед. онтогенеза. Полученные данные свидетельствуют об относительно низкой устойчивости сосны к действию повышенных концентраций цинка, проявляющейся в снижении всхожести семян, ингибировании роста и развития корневой системы (прежде всего, протяженности зоны образования вторичных корней, их количества и суммарной длины), нарушении динамики накопления биомассы различных органов и, в первую очередь, настоящей хвои, а также содержания основных фотосинтетических пигментов. Установлена специфика аккумуляции цинка в органах сеянцев, коррелирующая со степенью развития корневой системы. Выявлены конкурентные отношения между семядолями и хвоей сеянцев за эссенциальные элементы. Сделан вывод, что высокая чувствительность сосны обыкновенной к действию относительно низких концентраций цинка (50?150 мкМ) выгодно отличает ее от используемых в настоящее время модельных растений (Arabidopsis thaliana L., Mesembryanthemum cristallinum L., Brassica napus L. и др.). Это делает ее удобным объектом для изучения физиологических и молекулярных механизмов адаптации хвойных видов к тяжелым металлам, а также для предсказания возможных экологических последствий для древесных фитоценозов загрязнения окружающей среды цинком.

Иванова Е.М., Холодова В.П., Кузнецов В.В. Биологические эффекты высоких концентраций солей меди и цинка и характер их взаимодействия в растениях рапса // Физиология растений. 2010. Т. 57. № 6. С. 864-873

В экспериментах с растениями рапса (Brassica napus L.) сорта Вестар получено подтверждение значительно более высокой токсичности Cu по сравнению с Zn. Установлено, что сопоставимое по интенсивности токсическое действие оказывали соли CuSO4 в концентрациях 50 и 150 мкМ и ZnSO4 - 1000 и 2500 мкМ. Изучение действия Cu и Zn в этих концентрациях на содержание фотосинтетических пигментов и интенсивность перекисного окисления липидов не выявило причин различий в токсичности этих тяжелых металлов (ТМ). Среди изученных биологических эффектов существенные различия были обнаружены в органной локализации двух металлов как при росте растений на среде с высокими концентрациями Cu или Zn, так и на стандартной питательной среде. Cu, удерживаемая в корнях в относительно небольших количествах, слабо транспортировалась по надземной части растения, сохраняясь по преимуществу в нижних листьях и мало меняя свою локализацию в период восстановления после воздействия ТМ. Zn, напротив, оказался высоко мобильным, концентрируясь в листьях верхнего яруса и активно перемещаясь при переносе растений на среду с оптимальным содержанием ТМ. Высокие концентрации Cu сильно тормозили поступление Zn в корень, но практически не влияли на его передвижение по растению. Напротив, высокие концентрации Zn в среде способствовали поступлению Cu в корень, но препятствовали ее переносу в надземные органы. Представленные данные дают основание предположить, что в реализации токсического действия высоких концентраций изученных ТМ и механизмов адаптации к ним растений рапса важную роль играют биологические особенности органной и клеточной локализации Cu и Zn в растении и взаимовлияния этих ТМ при техногенном загрязнении среды.

Камалова Г.В., Акулов А.Н., Румянцева Н.И. Сравнение редокс-статуса клеток морфогенных и полученных из них неморфогенных каллусов гречихи татарской // Биохимия. 2009. Т. 74. № 6. С. 842-852.

Исследовали внутриклеточное содержание перекиси водорода и продукта перекисного окисления липидов - малонового диальдегида, а также активность антиоксидантных ферментов: каталазы, аскорбатпероксидазы и супероксиддисмутазы в клетках морфогенных и полученных из них неморфогенных каллусов гречихи татарской. Было установлено, что неморфогенные каллусы характеризовались значительно более высоким содержанием перекиси водорода и малонового диальдегида, низкой активностью каталазы и высокой активностью супероксиддисмутазы по сравнению с морфогенными культурами. Полученные результаты могут свидетельствовать о том, что клетки неморфогенных каллусов находятся в состоянии постоянного окислительного стресса. Тем не менее пролиферативная активность клеток неморфогенных культур и прирост биомассы были значительно выше по сравнению с клетками морфогенных каллусов. Проводится аналогия между раковыми клетками животных и неморфогенными каллусами растений.

Камалова Г.В., Нигматуллина Л.Р., Румянцева Н.И. Изменение морфо-цитогенетических и биохимических характеристик культивируемых клеток гречихи посевной при длительном культивировании // Ученые записки Казанского университета. Серия: Естественные науки. 2009. Т. 151. № 4. С. 103-111.

Изменение числа хромосом, содержания пероксида водорода и активности антиоксидантных ферментов - супероксиддисмутазы (СОД) и растворимой пероксидазы - в клетках каллусов гречихи посевной связано с различной способностью к морфогенезу при длительном культивировании (21 месяц). В каллусных культурах гречихи посевной морфогенной способностью обладают культуры с преобладанием диплоидных клеток и низким содержанием пероксида водорода. Потеря морфогенного потенциала с увеличением времени культивирования сопровождается уменьшением доли диплоидных клеток и увеличением содержания внутриклеточного пероксида водорода. Активность антиоксидантных ферментов не проявила четкой корреляции с морфогенной способностью каллусных культур. Полученные результаты указывают на наличие связи между изменением морфогенной способности, генетической вариабельностью и изменением редокс-статуса каллусных клеток с увеличением времени культивирования.

Костин В.И., Исайчев В.А., Ошкин В.А. Изучение взаимодействия микроэлементов и мелафена на технологические качества корнеплодов сахарной свёклы // Вестник Ульяновской государственной сельскохозяйственной академии. 2014. № 4 (28). С. 64-69.

При использовании внекорневых подкормок агроценоза сахарной свёклы нереутилизующимися микроэлементами бором, марганцем и цинком в сочетании с регулятором роста нового поколения мелафеном изучено физиологическое взаимодействие (антагонизм, синергизм, аддитивность) с использованием эмпирических формул, выведенных авторами. Коэффициенты синергизма рассматривали на показатели урожайности, сахаристости, доброкачественности нормального сока и выхода сахара, при этом установлено, что взаимодействие с использованием бора и мелафена происходит на уровне аддитивности и положительного синергизма. В данном случае проявляется анионное взаимодействие между борной и фосфиновой кислотами. Изучаемые явления, связаны не только с валентностью, но и с электронным строением атомов и ионов, то есть с электронной конфигурацией, а также распределением электронов по энергетическим уровням и подуровням, с этим связаны и химические свойства данных элементов. В результате исследований установлено, что практически все микроэлементы являются d-элементами со сходной электронной конфигурацией и между ними проявляется синергетическое взаимодействие. При взаимодействии микроэлементов d-семейства, как между элементами, так и совместно с мелафеном наблюдается только положительный синергизм, коэффициент синергизма колеблется от 0,16 до 0,38. По доброкачественности нормального сока абсолютный синергизм установлен только между микроэлементами и мелафеном, в остальных случаях - аддитивность и относительный синергизм.

Крылова Е.Г., Васильева Н.В. Действие сульфата никеля на начальные этапы онтогенеза растений трех видов рода Bidens (asteraceae) // Растительные ресурсы. 2011. Т. 47. № 1. С. 65-71.

Изучено влияние сульфата никеля (0.1-50 мг/л) на прорастание семянок и начальные этапы развития проростков растений влажных местообитаний: череды трехраздельной Bidens tripartita L., череды поникшей B. cernua L. и череды облиственной B.frondosa L. Прорастание семянок B. tripartita устойчиво к действию растворов сульфата никеля во всем указанном интервале концентраций. При концентрациях никеля 10-50 мг/л отмечено достоверное снижение лабораторной всхожести семянок B. frondosa и B. cernua, причем наибольшей чувствительностью обладают семянки последнего вида. Максимальное токсическое действие сульфат никеля оказывает на корневую систему проростков всех исследуемых видов. Надземная часть проростков в меньшей степени реагирует на повышенные концентрации никеля в среде. По устойчивости к действию сульфата никеля исследуемые виды располагаются в следующем убывающем ряду: B. tripartita > B. frondosa >B. cernua.

Лукаткин А.С., Грачева Н.В. и др. Цитокинин-подобные препараты ослабляют повреждения растений кукурузы ионами цинка и никеля // Физиология растений. 2007. Т. 54. № 3. С. 432-439.

На молодых растениях кукурузы (Zea mays L.), выращенных в водной культуре в присутствии ионов цинка и никеля, исследовали возможность снижения токсического действия тяжелых металлов (ТМ) синтетическими регуляторами роста цитокининового типа ? тидиазуроном и кинетином. При действии ТМ наблюдали подавление прорастания семян и роста молодых растений, изменение состояния мембран и активности аскорбатпероксидазы. Синтетические цитокинин-подобные препараты ослабляли негативные эффекты ТМ; степень влияния регуляторов роста зависела от концентрации и действующего иона. Токсическое действие Zn2+ наиболее эффективно снижалось кинетином, а действие Ni2+ тидиазуроном.

Минаева О.М., Акимова Е.Е., Минаев К.М., Семенов С.Ю., Писарчук А.Д. Поглощение ряда тяжелых металлов из водных растворов растениями водного гиацинта (Eichhornia Crassipes (mart.) solms) // Вестник Томского государственного университета. Биология. 2009. № 4. С. 106-111.

Изучено поглощение ионов меди, свинца, кадмия и цинка из водных растворов водным гиацинтом в модельных условиях. Отмечено, что растения выдерживают превышение ПДК данных элементов в воде, сохраняют жизнеспособность и успешно размножаются. За десять дней модельного эксперимента концентрация металлов снижается более чем в 5 раз для цинка, в 6 раз для кадмия, в 4 раза для свинца, в 8,5 раза для меди. При этом в вегетативной массе эйхорнии значительного накопления данных металлов не отмечено. Таким образом, показана эффективность использования растений водного гиацинта для очистки вод различного назначения от тяжелых металлов.

Невмержицкая Ю.Ю., Тимофеева О.А. и др. Стевиозид повышает устойчивость озимой пшеницы к действию низких температур и тяжелых металлов // Доклады Академии наук. 2013. Т. 452. № 3. С. 346-349.

Недведь Е. Л., Шалыго Н. В., Серова З. Я. Содержание глутатиона и активность глутатионредуктазы в растениях, инфицированных возбудителями бурой ржавчины и сетчатого гельминтоспориоза // Известия Национальной академии наук Беларуси. Серия биологических наук. 2007. № 2. С. 25-30.

Исследовали количественное содержание восстановленной (Г-SH) и окисленной (Г-SS-Г) форм глутатиона в тканях ржи и ячменя, инфицированных возбудителями бурой ржавчины и сетчатого гельминтоспориоза. Анализ полученных данных показал, что соотношение Г-SH / Г-SS-Г может служить критерием оценки развивающегося в тканях растений окислительного стресса, вызванного внедрением патогенов, и зависит от типа складывающихся в патосистемах отношений (облигатных или факультативных).

Нигматуллина Л.Р., Румянцева Н.И., Костюкова Ю.А. Влияние D,l-бутионин-S,R-сульфоксимина на соотношение форм глутатиона и рост каллусов гречихи татарской // Онтогенез. 2014. Т. 45. № 1. С. 50-62.

Исследовали внутриклеточное содержание восстановленной (GSH) и окисленной (GSSG) форм глутатиона, активности глутатионредуктазы, глутатион-S-трансферазы и аскорбатпероксидазы в морфогенном и неморфогенном каллусах гречихи татарской в ходе культурального цикла, а также при воздействии D,L-бутионин-S,R-сульфоксимина (БСО) - ингибитора первого фермента биосинтеза глутатиона -глутамилцистеинсинтазы. Было установлено, что в ходе пассажа культуры незначительно отличались по содержанию общего глутатиона, но содержание GSH было выше в морфогенной культуре, а содержание GSSG - в неморфогенной культуре. В морфогенном каллусе активность глутатион-S-трансфераз была в 10-20 раз выше, а активность глутатионредуктазы в 2-2.5 раза ниже, чем в неморфогенном. При действии БСО снижение содержания GSH в морфогенном каллусе было временным (на 6-8 сутки пассажа), а в неморфогенном оно снижалось уже через сутки и оставалось ниже, чем в контроле на протяжении всего пассажа. БСО не влиял на содержание GSSG в морфогенном каллусе, а в неморфогенном вызывал его накопление. Эти различия, вероятно, обусловлены тем, что на среде с БСО в морфогенном каллусе происходит активация глутатионредуктазы, а в неморфогенном каллусе, наоборот, глутатионредуктаза ингибируется. Несмотря на то, что БСО вызывал снижение общего содержания глутатиона только в неморфогенной культуре, цитостатический эффект БСО был более выражен в морфогенном каллусе. БСО также оказывал негативное влияние на дифференцировку проэмбриональных клеточных комплексов в морфогенном каллусе. Обсуждается роль редокс-статуса глутатиона в поддержании эмбриогенной активности культивируемых клеток растений.

Нурминский В.Н., Озолина Н.В., Нестеркина И.С. и др. Стабильность вакуолярных мембран растений при осмотическом стрессе и воздействии редокс-агентов // Биологические мембраны: журнал мембранной и клеточной биологии. 2011. Т. 28. № 3. С. 224-229.

Изучена стабильность вакуолярных мембран растений (тонопласта), подвергнутых двум видам осмотического стресса, воздействию редокс-агентов (глутатион в окисленной (GSSG) и восстановленной (GSH) формах) и оксида азота (NO), а также при различных значениях рН. Определен также жирнокислотный состав липидов тонопласта. Обнаружено, что при гиперосмотическом стрессе, в отличие от гипоосмотического, стабильность вакуолей снижалась. Эти эффекты, по-видимому, не связаны с жирнокислотным составом вакуолярных мембран. Стабильность вакуолей менялась в разных редокс-условиях, причем более интенсивно при гипоосмотическом стрессе в опытах с окисленным глутатионом. Влияние оксида азота различалось при разных видах стресса: при гипоосмотическом стрессе стабильность вакуолей значительно снижалась, тогда как при гиперосмотическом стрессе оксид азота повышал стабильность вакуолярных мембран.

Павлючкова С. М., Шалыго Н. В. Функционирование антиоксидантной системы трансгенных по Fe-СОД и Mn-СОД растений табака (Nicotiana tabacum) при низкотемпературном стрессе // Известия Национальной академии наук Беларуси. Серия биологических наук. 2012. № 2. С. 91-95.

Установлено, что растения табака, трансформированные смысловым геном хлоропластной Fe-CОД и митохондриальной Mn-СОД, в нормальных условиях выращивания обладают более высоким антиоксидантным потенциалом по сравнению с диким типом (ДТ) вследствие повышенной экспрессии супероксиддисмутазы (СОД), а также за счет более высокой активности аскорбатпероксидазы (АПР) и глутатионредуктазы (ГР), а в случае Mn-СОД трансформантов и за счет более высокого содержания аскорбата. При низкотемпературном стрессе (+4 0С, 22 ч) активация СОД, АПР, ГР и каталазы, а также уровни аскорбата и глутатиона в трансгенных растениях обоих вариантов значительно превышали дикий тип, что согласуется с низким уровнем активных форм кислорода и продуктов перекисного окисления липидов в трансгенных по Fe-CОД и Mn-СОД растениях табака.

Прадедова Е.В., Толпыгина О.А. и др. Глутатион и глутатион-S-трансферазная активность вакуолей корнеплодов столовой свеклы (Beta vulgaris L.) // Доклады Академии наук. 2010. Т. 433. № 4. С. 570-573.

Радомская B.И., Моисеенко Н.В. и др. Влияние осадков сточных вод на поведение тяжелых металлов в системе почва-растение // Агрохимия. 2006. № 1. С. 77-84.

Рассмотрено влияние высоких доз осадков городских сточных вод в условиях модельного опыта на изменение агрохимических свойств почвы, подвижность тяжелых металлов и ряд показателей качества сельскохозяйственной продукции. При внесении осадков сточных вод в почве увеличилось количество обменного кальция, общего азота, фосфора, органического вещества, что положительно повлияло на урожайность. Однако возрастание доли водорастворимых и подвижных форм тяжелых металлов способствовало их накоплению в зерне и получению продукта с превышением ПДК свинца, цинка, меди.

Сибиркина А.Р. Биогеохимическая оценка содержания тяжелых металлов в листьях кустарниковых растений соснового бора Семипалатинского Прииртышья // Актуальные проблемы гуманитарных и естественных наук. 2013. № 11-1. С. 74-77.

Получены данные о содержании тяжелых металлов в листьях кустарниковых растений соснового бора Семипалатинского Прииртышья. Выявлены виды кустарниковых растений, накапливающие наибольшее и наименьшее содержание тяжелых металлов.

Солдатова Н.А., Хрянин В.Н. Антиоксидантная система защиты растений Cannabis sativa L. при действии соли цинка // Известия Пензенского государственного педагогического университета им. В.Г. Белинского. 2011. № 25. С. 632-634.

Изучали ответную защитную реакцию растений Cannabis sativa L. на действие разных концентраций соли цинка. Показано, что в ответ на действие тяжелого металла, который является стрессором для растений, происходит активация защитной антиоксидантной системы.

Степанов М.Е., Белодурин Д.В. и др. Перекисное окисление липидов в тканях растений кукурузы и ржи при действии ионов цинка // Вестник Мордовского университета. 2009. № 1. С. 210-212.

В побегах и корнях 7-дневных растений кукурузы и ржи определяли интенсив- ность перекисного окисления липидов (ПОЛ) под действием цинка. Выявлено, что для побегов растений есть прямая зависимость интенсивности процессов ПОЛ от концентрации металла, на которой выращивалось растение. Для проростков кукуру- зы концентрация 10 ммоль / л оказалась летальной и растения не выросли. В кор- нях изменения ПОЛ более значительны, чем в листьях. Возможно, корни реагируют интенсивнее из-за того, что цинк более всего аккумулируется в семенах и корнях.

Стеценко Л.А., Шевякова Н.И. и др. Пролин защищает растения Atropa belladonna от токсического действия солей никеля // Физиология растений. 2011. Т. 58. № 2. С. 275-282.

Растения Atropa belladonna L. выращивали в водной культуре и в возрасте 8 нед. в питательную среду однократно вносили NiCl2 до конечных концентраций 0 (контроль), 50, 100, 150, 200, 250 и 300 мкМ. Через 4 суток действия хлористого никеля в растениях измеряли содержание воды, анализировали содержание пролина, Ni, Fe, свободных полиаминов (ПА), а также интенсивность перекисного окисления липидов (ПОЛ). Добавление в среду 100?150 мкМ Ni приводило к значительному снижению прироста биомассы и содержания воды в тканях растений по сравнению с контролем; 200 мкМ Ni вызывал серьезные повреждения растений, совместимые с жизнеспособностью A. belladonna, тогда как концентрации Ni 250 и 300 мкМ оказались летальными. В надземной части растений наибольшее количество Ni аккумулировали листья верхушки побега, которые содержали 220 мкг Ni/г сухой массы при добавлении в среду 200 мкМ Ni; при этом в корнях содержание Ni достигало 1500 мкг/г сухой массы. Обработка растений пролином в присутствии 200 мкМ Ni в среде ингибировала поступление этого элемента в ткани, увеличивала содержание железа в листьях и, особенно, в корнях, снижала интенсивность ПОЛ и стабилизировала водный статус листьев. При действии 200 мкМ Ni наблюдали некоторое снижение содержания свободного путресцина и увеличение уровней спермина и спермидина в листьях по сравнению с контролем. Токсическое действие никеля сопровождалось не только стимуляцией накопления высокомолекулярных ПА, но и их окислительной деградацией, что проявлялось в 14-кратном увеличении содержания 1,3-диаминопропана. Защитный эффект экзогенного пролина в условиях действия высоких концентраций никеля проявлялся в снижении интенсивности ПОЛ, в уменьшении дефицита железа и в торможении окислительной деградации ПА.

Толкачёва Т.А., Балаева-Тихомирова О.М., Авласевич О.В. Перспективы применения культивируемых раннецветущих растений для получения экстрактов антиоксидантного действия // Современные тенденции развития науки и технологий. 2015. № 7-1. С. 51-53.

В статье определено содержание компонентов ферментативной и неферментативной антиоксидантной системы раннецветущих растений. Обосновано культивирование раннецветущих растений с последующим использованием сырья для антиоксидантных экстрактов.

Трухан И.С., Прадедова Е.В., Нимаева О.Д., Саляев Р.К. Глутатион и глутатионредуктаза вакуолей клеток корнеплодов столовой свеклы // Вестник ИрГСХА. 2013. № 55. С. 29-36.

В вакуолях клеток корнеплодов столовой свеклы (Beta vulgaris L.) выявлены глутатион (GSH) и фермент, регулирующий его редокс-состояние, - глутатионредуктаза (GR, КФ Проведен сравнительный анализ содержания GSH и уровня активности GR вакуолей и экстрактов тканей корнеплода. Установлено, что вакуоли содержали, по меньшей мере, 0.8 мМ GSH, тогда как в тканевом экстракте его концентрация могла достигать 1.5 мМ. Активность GR вакуолей была в 1.5-2 раза выше активности фермента тканевых экстрактов, при этом Km фермента для GSSG отличались незначительно. На поздней стадии покоя корнеплода Vm глутатионредуктазы вакуолей и тканевых экстрактов увеличивалась в 2.5 раза, тогда как Km мало изменялись.

Чжао Ф.Ю., Лю Т., Сюй Ч.Ц. Совместное действие солевого и теплового стрессов на рост корней и системы нейтрализации активных форм кислорода трансгенного риса // Физиология растений. 2010. Т. 57. № 4. С. 556-563.

Исследовали рост корней и системы нейтрализации АФК в трансгенном рисе (Oryza sativa L., сорт Zhonghua N. 11), ко-экспрессирующем глутатион-S-трансферазу (GST, КФ и каталазу 1 (КАТ1, КФ, и в нетрансгенном рисе, подвергнутых либо только солевому или тепловому стрессам, либо их комбинации. После воздействия стрессами, у трансгенных растений наблюдали увеличение числа придаточных корней и снижение отношения корней к побегу по сравнению с растениями дикого типа. При всех типах стресса, активность большинства ферментов антиоксидантной защиты, таких как КАТ, GST, аскорбатпероксидаза (АПО, КФ, глутатионредуктаза (ГР, КФ и дегидроаскорбатредуктаза (ДГАР, КФ, а также степень восстановленности глутатиона и аскорбата в корнях трансформантов достоверно отличались от соответствующих параметров в корнях нетрансформированных растений. Влияние стрессов на рост корней и активность антиоксидантных систем в трансгенном рисе могут быть объяснены не только наличием в нем трансгенов для GST и КАТ1, но также координированным функционированием аскорбат?глутатионового цикла.

Шалыго Н. В., Доманская И. Н. и др. Влияние водного дефицита на редокс-статус глутатиона в зеленых проростках ячменя (Hordeum vulgare 1.) // Известия Национальной академии наук Беларуси. Серия биологических наук. 2007. № 4. С. 64-68.

Модифицирован метод определения восстановленного (GSH) и окисленного (GSSG) глутатиона в растительных тканях. Изучено изменение соотношения GSH / GSSG в проростках ячменя в зависимости от продолжительности засухи. Показано, что в лабораторных условиях при водном дефиците происходит увеличение показателя GSH / GSSG.

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