Mobilization of seed reserves pretreated with H2O2 during germination and establishment of sunflower seedlings under salinity

Abstract

Several studies have shown hydrogen peroxide (H₂O₂) as a metabolic messenger that increases plant tolerance to various stress conditions. However, little is known about its effect on the mobilization of seed reserves in the establishment of seedlings. Thus, this study aimed to evaluate the effect of pretreatment with H₂O₂ in salt-tolerance and mobilization of reserves during the germination of seeds and establishment of sunflower seedlings. Seeds were pre-imbibed for 24?hr in solutions containing: deionized water (control); H₂O₂ (1?mM); NaCl (100?mM). Subsequently, seeds were distributed on germitest paper, moistened with deionized water or saline solution (100?mM NaCl). In seedlings not pretreated with H₂O₂, the salinity increased Na⁺ and Cl^? ions contents and reduced the growth of sunflower seedlings. However, pretreatment of seeds with H₂O₂ reduced the negative effect of salinity, promoted an increase in salt-tolerance by the reduction of Na⁺ and Cl^? uptake, lower energy cost for osmoprotection by compatible solutes accumulation, and by the higher equilibrium in the mobilization of the cotyledon reserves for the development of the embryonic axis.     

La(NO3)3 对盐胁迫下黑麦草幼苗生长及抗逆生理特性的影响

为探讨稀土元素镧(La)对牧草盐胁迫伤害的缓解作用, 采用水培法研究了叶面喷施20 mg·L^-1La(NO₃)₃ 对NaCl 胁迫下黑麦草幼苗生长及其抗逆生理特性的影响。结果表明: 盐胁迫显著抑制黑麦草幼苗的生长, 提高叶片电解质渗漏率及丙二醛(MDA)、O₂^- 和H₂O₂ 含量, 其作用随盐浓度的增大而增强。超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、可溶性蛋白质、脯氨酸含量随盐浓度增大呈先升后降趋势, 可溶性糖和Na⁺/K⁺比逐渐增大, 质膜H⁺-ATP 酶活性逐渐降低, 过氧化物酶(POD)活性及POD 同功酶数量表达增强。喷施La(NO₃)₃ 处理可降低盐胁迫下黑麦草幼苗叶片的O₂^- 和H₂O₂ 含量, 提高SOD、CAT、POD、APX 和质膜H⁺-ATP 酶的活性及POD 同功酶的表达, 使AsA、GSH、可溶性蛋白质、可溶性糖和游离脯氨酸含量及幼苗生物量增加, Na⁺/K⁺比降低。表明La(NO₃)₃ 可通过提高抗氧化系统的活性和积累渗透溶质减轻盐胁迫伤害, 从而提高黑麦草的耐盐性。     

镉诱导拟南芥根尖过氧化氢积累导致植物根生长抑制

以模式植物拟南芥为材料研究了植物主根对不同浓度镉胁迫的响应。结果表明,随镉浓度的升高,植物主根生长受到明显抑制,胎盘兰染色表明高剂量的镉造成主根根尖细胞死亡。进一步二氨基联苯胺(DAB)染色发现镉胁迫诱导植物根尖大量积累过氧化氢,而在胁迫培养基中加入维生素C可显著改善植物根的生长、降低过氧化氢积累,并减少镉诱导的根尖细胞死亡。上述结果表明,镉胁迫诱导的拟南芥主根生长抑制很可能是由于根尖细胞过氧化物积累所致。     

CO2激光与外源NO对低温胁迫小麦的防护效应

以冬小麦‘小堰22号’为试验材料,研究了CO2激光与外源一氧化氮(NO)复合作用对低温胁迫(4℃)下小麦幼苗自由基双氧水(H2O2)、超氧阴离子(O2?)浓度,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)、一氧化氮合成酶(NOS)活性,一氧化氮(NO)及蛋白质含量,及幼苗生长发育的影响。结果表明:与单独低温胁迫相比,外源NO处理后低温胁迫和CO2激光处理后低温胁迫都显著降低了H2O2和O2?浓度,提高了SOD、CAT、POD、APX、NOS活性,NO和蛋白质含量,促进幼苗生长发育。外源NO处理后再进行CO2激光辐射,虽然可以降低低温胁迫下幼苗H2O2和O2?浓度,提高SOD、CAT、POD、APX、NOS活性及NO和蛋白质浓度,促进幼苗生长发育,但其保护效应明显低于外源NO处理后低温胁迫和CO2激光处理后低温胁迫的效果。上述结果说明,NO对低温胁迫的防护效应优于NO和CO2激光复合处理。因此,建议在农业生产中单独采用NO处理或者CO2激光处理,可以促进农作物对低温胁迫的抗性。     

外源一氧化氮对镉胁迫下长春花质膜过氧化、ATPase及矿质营养吸收的影响

重金属污染已成为全球范围的主要问题之一,其中土壤镉（Cd）污染已成为当今社会普遍关注的问题。镉是植物生长发育的非必需元素,极小浓度即可产生较大危害。一氧化氮（NO）是一种氧化还原信号分子和活性氮（RNS）, 参与植物对重金属镉胁迫的应答。长春花（Catharanthus roseus）是我国广泛栽培的兼具园林绿化和抗癌药源等有重要价值的多年生草本花卉植物。为了解镉胁迫下外源NO 对园林地被植物生理响应的调控机制,采用盆栽试验研究了外源NO（硝普钠SNP）对镉胁迫下长春花幼苗生长、 活性氧代谢、 质膜ATPase酶和5'-核苷酸酶活性以及矿质营养元素吸收的影响。结果表明, 25 mg/kg 镉胁迫严重抑制长春花幼苗的生长,显著增加地上部和根系镉的富集量,抑制对大量元素和微量元素的吸收。施加0.45、 0.90、 1.80 mg/kg 的SNP显著降低镉从根系向地上部的转运,缓解因镉胁迫对钾（K）、 钙（Ca）、 镁（Mg） 和 铁（Fe）、 铜（Cu）、 锌（Zn） 吸收产生的抑制效应,降低镉胁迫的毒害作用,促进植物生长。镉胁迫下,丙二醛（MDA）含量和活性氧（O2和H2O2）水平显著升高。施加低浓度 SNP 能够显著缓解细胞质膜过氧化,降低硫代巴比妥酸反应产物（TBARS）堆积,且对抗氧化酶和ATPase酶具有相同作用。添加0.45、 0.90、 1.80 mg/kg 的SNP 可提高镉胁迫下长春花地上部和根系的抗氧化酶［过氧化氢酶（CAT）、 超氧化物歧化酶（SOD）、 过氧化物酶（POD）］活性与抗氧化物（还原型谷胱甘肽GSH）含量,诱导质膜H+-ATPase、 Ca2+-ATPase和 5-AMPase 活性提升到正常水平（对照CK）。添加1.80 mg/kg 的SNP对镉毒害的缓解作用最有效,而添加3.60、 7.20 mg/kg 的SNP的处理则无明显效果。     

燕麦幼苗对氯化钠和氯化钾胁迫的生理响应差异

为探讨燕麦对NaCl和KCl胁迫的生理响应差异,采用水培法,研究了不同浓度NaCl和KCl胁迫对幼苗生长,活性氧代谢和渗透调节的影响。结果表明:(1)在75和150mmol/L浓度下,NaCl胁迫对燕麦幼苗的膜脂过氧化伤害和生长抑制大于KCl胁迫。NaCl胁迫下叶片中的超氧化物岐化酶(SOD),过氧化氢酶(CAT)活性及可溶性蛋白、可溶性糖和脯氨酸含量低于KCl胁迫;当浓度增大到225mmol/L时,KCl胁迫叶片中O-2.,H2O2,丙二醛(MDA),可溶性蛋白和可溶性糖含量显著大于NaCl胁迫,而SOD,抗坏血酸过氧化物酶(APX)活性及谷胱甘肽(GSH)含量则相反。(2)225mmol/L KCl和NaCl处理的植株叶片水势分别为-0.867和-1.034 MPa,渗透势分别为-1.409和-1.252 MPa,说明KCl对燕麦的更强伤害不是渗透胁迫所致;经225mmol/L KCl胁迫后,燕麦叶片中Na+含量下降至对照的36.5%,而K+含量上升为对照的1.49倍,而补充20mmol/L NaCl显著提高了225mmol/L KCl胁迫下叶片Na+的含量及SOD,APX活性,降低了K+,H2O2,O-2.和MDA含量,说明离子毒害引起的活性氧积累可能是高浓度KCl胁迫对燕麦幼苗伤害大于NaCl胁迫的重要原因。     

Oxidative Stress Induced by Cadmium and Copper in Brassica rapa Leaves: Indicators of Stress,Oxidative Damage,and Antioxidant Mechanisms

Brassica rapa is frequently used as a vegetable for human consumption and can accumulate metals that are bioavailable in soils. We studied the oxidative stress induced by 25 μM cadmium (Cd) and 50 μM copper (Cu) on Brassica rapa leaves and evaluated the intracellular antioxidative plant response mechanisms and the accumulation of these metals. With this purpose, hydrogen peroxide (H₂O₂) concentration, lipid peroxidation, and enzymatic and nonenzymatic responses was determined. The obtained results indicate that Cd and Cu induced different plant responses. Oxidative stress induced by Cu was characterized by increased lipid peroxidation and free proline levels. Guaiacol peroxidase and ascorbate peroxidase showed a relevant role in H₂O₂ removal. Cadmium did not influence lipid peroxidation, H₂O₂, proline and glutathione contents, and the enzymatic response mainly involves superoxide dismutase and ascorbate peroxidase. It was concluded that both excess Cu and Cd induced oxidative stress but plant response is characterized by different antioxidative response mechanisms.     

Zinc‐biofortified seeds improved seedling growth under zinc deficiency and drought stress in durum wheat

High zinc (Zn) concentration of seeds has beneficial effects both on seed vigor and human nutrition. This study investigated the effect of Zn biofortification on growth of young durum wheat (Triticum durum cv. Yelken) seedlings under varied Zn and water supply. The seeds differing in Zn concentrations were obtained by spraying ZnSO₄ to durum wheat plants at different rates under field conditions. Three groups of seeds were obtained with the following Zn concentrations: 9, 20, and 50 mg Zn kg^?1. The seeds differing in Zn were tested for germination rate, seedling height, shoot dry matter production, and shoot Zn concentration under limited and well irrigated conditions in a Zn‐deficient soil with and without Zn application. In an additional experiment carried out in solution culture, root and shoot growth and superoxide dismutase activity (SOD) of seedlings were studied under low and adequate Zn supply. Low seed Zn concentration resulted in significant decreases in seedling height both in Zn‐deficient and sufficient soil, but more clearly under water‐limited soil condition. Decrease in seed germination due to low seed Zn was also more evident under limited water supply. Increasing seed Zn concentration significantly restored impairments in seedling development. Drought‐induced decrease in seedling growth at a given seed Zn concentration was much higher when soil was Zn‐deficient. Increasing seed Zn concentration also significantly improved SOD activity in seedlings grown under low Zn supply, but not under adequate Zn supply. The results suggest that using Zn‐biofortified seeds assures better seed vigor and seedling growth, particularly when Zn and water are limited in the growth medium. The role of a higher antioxidative potential (i.e., higher SOD activity) is discussed as a possible major factor in better germination and development of seedlings resulting from Zn‐biofortified seeds.     

Nitrate assimilation and biomass production in Sesamum indicuml. Seedlings in a lead enriched environment

Seed germination was delayed and seedling growth inhibited by 0.04 to 1.9 mM Pb⁺² in Sesamum indicum L. var HT-I. In root, shoot and leaf Pb⁺² accumulation increased with increasing Pb⁺² concentration in the nutrient solution. In root and leaf tissues in vivo and in vitro nitrate reductase activity was inhibited significantly which was well correlated with the concentration of Pb⁺² supplied and its accumulation in the plant parts. The inhibition of the NR enzyme activity could be, however, reversed by simultaneous treatment of Sesamum seedlings with K₂HPO₄, CaCl₂ and KNO₃ dissolved in nutrient solution. Total organic N and soluble protein of roots and shoots/leaves, on the other hand, increased with increasing concentration of Pb⁺² while the same treatment caused a decrease in the N content of cotyledons. It appears therefore, that the increase in N and protein in the roots, shoots/leaves may be a result of increased translocation of N from the cotyledons to the roots and shoots/leaves during early seedling growth in a Pb⁺² enriched environment.     

顽拗性板栗种子成熟前后褐变与可溶性糖的关系

试图揭示板栗种子褐变与脱水敏感性和可溶性糖含量之间的关系。板栗种子成熟脱落时，脱水敏感性相对较弱，子叶和胚轴中棉籽糖和水苏糖含量达最高峰，电导率和紫外吸收值最低，总酚含量与POD活性较低。种子脱落后，脱水敏感性上升，子叶和胚轴中棉籽糖和水苏糖含量下降，膜渗漏物质增多，总酚含量及POD活性急剧上升，从而导致褐变发生。胚轴中总酚含量与POD活性存在显著的正相关(r=0.999)，而棉籽糖含量分别与POD活性和总酚含量存在显著的负相关(r分别为－0.998和－0.995)。结果表明，可溶性糖的组分及其含量可能与板栗种子脱水敏感性大小有关，板栗种子脱落后还原性糖麦芽糖含量的上升与褐变的发生趋势一致，而非还原性糖特别是棉籽糖可能在抑制褐变方面具有一定作用。     

不同NaCl浓度微咸水灌溉对棉花幼苗生理特性的影响

为找出棉花苗期微咸水灌溉的适宜浓度,明确滨海盐土区微咸水在棉花苗期代替淡水灌溉的可行性。本研究在盆栽试验条件下,研究了浇灌不同NaCl浓度的微咸水对棉花幼苗生理特性的影响。结果表明:与CK相比,NaCl浓度为4 g/L的微咸水处理显著降低了棉籽发芽率,达26.09%,而NaCl浓度为2~3 g/L的微咸水处理与对照无显著差异。与CK相比,NaCl浓度为4 g/L的微咸水处理显著降低了棉花幼苗的鲜重、株高、根长和干重,降低幅度分别为34.08%、27.27%、38.26%和35.29%;显著降低了棉花幼苗叶绿素含量,提高了抗氧化酶活性、可溶性蛋白含量和游离脯氨酸含量;增加了棉花幼苗超氧阴离子的产生速率、H_2O_2含量及丙二醛积累量。NaCl浓度为3 g/L的微咸水处理对棉花幼苗的部分生长和生理指标也具有显著的抑制作用。NaCl浓度为2 g/L的微咸水处理对棉花幼苗的生长没有显著的抑制作用,可以在黄河三角洲地区棉花幼苗期代替淡水灌溉。     

Effect of Increasing Concentration of Inorganic Phosphate (Pi) and Pyrophosphate (PPi) on Growth and Phosphatases of Germinating Chickpea Seeds

Chickpea (Cicer arietinum L.) seedlings growing on different concentrations of inorganic phosphate and pyrophosphate in agar based MS-medium were studied for their growth and activities of phosphatases in cotyledon, shoots and roots. Growth of seedlings was affected with both Inorganic Phosphate (Pi) and Pyrophosphate (PPi). Germination was completely inhibited beyond 100 mM monopotassium phosphate (KH₂PO₄) and 20 mM sodium pyrophosphate. Specific activities of acid phosphatases of cotyledons, shoots and roots decreased under high Pi-supply however alkaline phosphatases were not affected. Addition of PPi increased specific activities of acid phosphatases of roots and shoots at 3 days after germination (DAG) stage, but decreased at later stages of seedling growth. There was an appearance of PPi-specific acid phosphatase in roots under PPi-supply.     

Impact of Boron Deficiency on Changes in Biochemical Attributes,Yield, and Seed Reserves in Chickpea

To determine the effect of boron (B) deficiency on biomass, reproductive yield, metabolism, and alterations in seed reserves of chickpea (Cicer arietinum L.) cv. ‘13.G‐256,’ plants were grown in refined sand until maturity at deficient (0.033 mg L^?1) and adequate (0.33 mg L^?1) B, supplied as boric acid (H₃BO₃). Boron‐deficient plants exhibited visible deficiency symptoms in addition to reduced number of pods and seeds, resulting in lowered biomass and economic yield. Boron deficiency lowered the concentration of B in leaves and seeds, photosynthetic pigments (leaves), Hill reaction activity, starch (in leaves and seeds), and proteins and protein N (in seeds), whereas phenols, sugars (in leaves and seeds), and nonprotein N (in seeds) were elevated. Specific activity of peroxidase (POX) increased in leaves and pod wall and decreased in seeds, while activity of acid phosphate and ribonuclease were stimulated in leaves, seeds, and pod wall in B‐deficient chickpea.     

Copper Stress Affects Metabolism and Reproductive Yield of Chickpea

To observe the effects of copper (Cu) deficiency on growth, metabolism, and reproductive yield of chickpea (Cicer arietinum L.) cv. ‘13.G-256’, plants were grown in refined sand at deficient (0.1 μM) and adequate Cu (1 μM), supplied as copper sulfate (CuSO₄·5H₂O). At d 35–40, at deficient Cu, the growth of plants were depressed and the young leaflets appeared reduced in size, chlorotic, with narrow pointed tips. The primary branches collapsed later, and secondary branches were stunted with reduced number of leaves. The flowering was disturbed, less flowers matured, as a consequence pods and seeds were reduced, malformed and low in productivity, which lowered biomass and economic yield and is accompanied by decrease in Cu concentration in leaves and seeds. The quality of seeds deteriorated at deficient Cu as the concentration of proteins, carbohydrates (sugars and starch), protein nitrogen were lowered, and phenols, non-protein nitrogen, increased. Whereas in leaves, the concentration of carbohydrates (sugars and starch), phenols, and non-protein nitrogen were elevated and protein nitrogen was reduced. Copper deficiency also alleviated the concentration of chlorophyll (a and b) in leaves. At deficient Cu, the activity of antioxidative enzyme viz. peroxidase along with that of acid phosphatase and ribonuclease increased in leaves, seeds and pod wall of chickpea.     

The natural aging-related biochemical changes in the seeds of two legume varieties stored for 40 years

Abstract

This study was carried out to evaluate the effect of long-term natural aging on germinability and several biochemical characteristics regarding antioxidative response of both dry and germinating two different clover (Trifolium repens and Trifolium pratense) seeds stored for 40 years. The percent germination of the seeds was monitored for 7 days. The activities of catalase, peroxidase, superoxide dismutase, lipid peroxidation, H₂O₂ levels, and phenolic matter content were tested on 0, 1st, 3rd, and 7th days of germination. On the 7th day of germination, the germination ratios of the old T. repens and T. pratense seeds were 32 and 17%, while freshly harvested seeds showed 99 and 96% germination on the 4th day, respectively. The long-term aging caused an important increase in lipid peroxidation levels of the old dry seeds. Total phenolic content was high in the old dry seeds of T. repens compared with those of T. pratense. Remarkably, the long-term aging caused an important decrease in H₂O₂ content and the activities of catalase and peroxidase enzymes, but an increase in activity of superoxide dismutase in both the old dry seeds. The decreases in germinability of the old legume seeds were well correlated with the increasing level of lipid peroxidation and the decreasing activities of peroxidase and catalase. During the germination of the legume seeds, a noticeable increase was determined only in peroxidase activity in two types of the old seeds, while catalase activity decreased. However, the other biochemical parameters studied did not significantly change between the germinating old seeds and their freshly harvested controls.     

Differences in Ozone Sensitivity at Different NPK Levels of Three Tropical Varieties of Mustard (Brassica campestris L.): Photosynthetic Pigments, Metabolites, and Antioxidants

The effects of ambient O₃ at two different levels of nitrogen, phosphorus, and potassium, (recommended and 1.5 times the recommended NPK) on three tropical varieties of mustard (Brassica campestris L. var. Kranti, Aashirwad and Vardan) were explored to unravel the mechanism of protection under higher NPK level at a rural experimental site using open top chambers. Ambient O₃ concentrations ranged from 27.7 to 59.04 ppb. Lipid peroxidation, antioxidative enzymes, and metabolites were higher, whereas photosynthetic pigments and protein were lower in all the varieties of mustard grown in non-filtered chambers than in filtered chambers. The magnitude of response varied with varieties, NPK levels and ages. Vardan showed a maximum stimulation in the antioxidative defense system, thus efficient scavenging of ROS produced by O₃ and consequently conferred greater tolerance in terms of least reductions in pigments and protein as compared to Kranti and Aashirwad. The antioxidant defense system was not stimulated in response to 1.5 times the recommended NPK, but higher levels of pigments and protein were maintained compared to the recommended NPK under ambient O₃ levels.     

Antagonistic effect of gibberellic acid and boron on protein and carbohydrate metabolism of soybean germinating seeds

Lots of soybean seeds (Glycine max L. Merr. cv MG 13 G2) were pretreated with solutions of boron (1 or 2 μg/ml) or/and gibberellic acid (GA₃) (0.1 μg/ml) during three hours, and germinated in a culture chamber at 24°±1°C. Germination and seedling growth were inhibited by boron. GA₃ activated both processes and partially reversed the inhibitory effect of the microelement. This protective effect of GA₃ against the negative action of boron is particularly due to the antagonism GA₃ /boron on protein and carbohydrate metabolism during the seed germination process.     

Thiamine (vitamin B1) seed treatment enhances germination and seedling growth of bean (Phaseolus vulgaris L.) exposed to soaking injury

Seed treatment with thiamine mononitrate significantly increased germination rate of bean (Phasenius vulgaris L.) seedlings germinated at high soil moisture levels and low night-temperature (5° C). Beneficial effects of thiamine applications on germination were also observed in soil-free germination tests when the seeds were submerged in water for 1–4 d at 18°C. Optimum response was achieved at thiamine concentrations of 3 mM, applied during the first 24 h of imbibition. As an early response to the thiamine treatment, vital staining with triphenyltetrazolium chloride revealed a lower proportion of damaged tissue of the embryonic axes. In later stages of seedling development, thiamine seed treatment resulted in a lower proportion of abnormal seedlings with malformations of the shoot apex and of the primary leaves. The beneficial effect of thiamine was more pronounced when the temperature during submergence was kept at 25° C compared to 5° C. There was no response to thiamine applications when the germinating seeds were exposed to low temperature treatments only. The thiamine effect could be mimicked by raising the osmotic potential of the incubation medium, indicating a relationship to soaking injuries. The results suggest that normal seedling development may be impaired by thiamine deficiency in the embryonic tissue induced by soaking injury, whereas low temperatures are not involved as a stress-factor.     

Effect of different foliar zinc application at different growth stages on seed zinc concentration and its impact on seedling vigor in rice

This study evaluated how zinc (Zn) concentration of rice (Oryza sativa L.) seed may be increased and subsequent seedling growth improved by foliar Zn application. Eight foliar Zn treatments of 0.5% zinc sulfate (ZnSO₄?·?7H₂O) were applied to the rice plant at different growth stages. The resulting seeds were germinated to evaluate effects of seed Zn on seedling growth. Foliar Zn increased paddy Zn concentration only when applied after flowering, with larger increases when applications were repeated. The largest increases of up to ten-fold were in the husk, and smaller increases in brown rice Zn. In the first few days of germination, seedlings from seeds with 42 to 67?mg Zn?kg^?1 had longer roots and coleoptiles than those from seeds with 18?mg Zn?kg^?1, but this effect disappeared later. The benefit of high seed Zn in seedling growth is also indicated by a positive correlation between Zn concentration in germinating seeds and the combined roots and shoot dry weight (r?=?0.55, p?相似文献   

The role of oxidative stress in spring barley cross-adaptation to different heavy metals

The aim of this study is to investigate the possibilities and the mechanisms of spring barley (Hordeum vulgare L.) cross-adaptation to different heavy metals after hardening with ozone (O₃), drought and UV-B radiation. Dry shoot biomass, accumulation of superoxide (O₂˙^?) and malondialdehyde (MDA), and activities of enzymes superoxide dismutase (SOD), glutathione reductase (GR) and catalase (CAT) were measured after hardening and heavy metal treatments. Seedlings, exposed to ozone and drought prior to copper (Cu) treatment, showed significantly increased tolerance to this heavy metal. The most possible causes of cross-adaptation to this redox-active heavy metal, which triggered very strong oxidative stress in nonhardened barley seedlings, were increased CAT activity, mitigation of O₂˙^? accumulation and lipid peroxidation. Cross-adaptation to cadmium (Cd) was induced only by drought hardening. In this case, however, adaptation had lower effect on antioxidative enzymes, did not altered O₂˙^? accumulation and even slightly increased the intensity of lipid peroxidation. The study reveals that stimulation of CAT activity and mitigation of oxidative stress are the main reasons for plant adaptation to Cu; whereas cross-adaptation to Cd, heavy metal with much lower oxidative capacity, is determined by the mechanisms that are not related to oxidative stress directly.