Comparative lipid peroxidation,antioxidant defense systems and proline content in roots of two rice cultivars differing in salt tolerance

The changes in the activity of antioxidant enzymes such as superoxide dismutase (SOD: EC 1.15.1.1), catalase (CAT: EC 1.11.1.6), peroxidase (POX: EC 1.11.1.7), ascorbate peroxidase (APOX: EC 1.11.1.11) and glutathione reductase (GR: EC 1.6.4.2), free proline content, and the rate of lipid peroxidation level in terms of malondialdehyde (MDA) in roots of two rice cultivars (cvs.) differing in salt tolerance were investigated. Plants were subjected to three salt treatments, 0, 60, and 120 mol m⁻³ NaCl for 7 days. The results showed that activated oxygen species may play a role in cellular toxicity of NaCl and indicated differences in activation of antioxidant defense systems between the two cvs. The roots of both cultivars showed a decrease in GR activity with increase in salinity. CAT and APOX activities increased with increasing salt stress in roots of salt-tolerant cultivar Pokkali but decreased and showed no change, respectively, in roots of IR-28 cultivar. POX activity decreased with increasing NaCl concentrations in salt-tolerant Pokkali but increased in IR-28. SOD activity showed no change in roots of both cultivars under increasing salinity. MDA level in the roots increased under salt stress in sensitive IR-28 but showed no change in Pokkali. IR-28 produced higher amount of proline under salt stress than in Pokkali. Increasing NaCl concentration caused a reduction in root fresh weight of Pokkali and root dry weight of IR-28. The results indicate that improved tolerance to salt stress in root tissues of rice plants may be accomplished by increased capacity of antioxidative system.     

An Enhancing Effect of Exogenous Mannitol on the Antioxidant Enzyme Activities in Roots of Wheat Under Salt Stress

The role of mannitol as an osmoprotectant, a radical scavenger, a stabilizer of protein and membrane structure, and protector of photosynthesis under abiotic stress has already been well described. In this article we show that mannitol applied exogenously to salt-stressed wheat, which normally cannot synthesize mannitol, improved their salt tolerance by enhancing activities of antioxidant enzymes. Wheat seedlings (3 days old) grown in 100 mM mannitol (corresponding to −0.224 MPa) for 24 h were subjected to 100 mM NaCl treatment for 5 days. The effect of exogenously applied mannitol on the salt tolerance of plants in view of growth, lipid peroxidation levels, and activities of antioxidant enzymes in the roots of salt-sensitive wheat (Triticum aestivum L. cv. Kızıltan-91) plants with or without mannitol was studied. Although root growth decreased under salt stress, this effect could be alleviated by mannitol pretreatment. Peroxidase (POX) and ascorbate peroxidase (APX) activities increased, whereas superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR) activities decreased in Kızıltan-91 under salt stress. However, activities of antioxidant enzymes such as SOD, POX, CAT, APX, and GR increased with mannitol pretreatment under salt stress. Although root tissue extracts of salt-stressed wheat plants exhibited only nine different SOD isozyme bands of which two were identified as Cu/Zn-SOD and Mn-SOD, mannitol treatment caused the appearance of 11 different SOD activity bands. On the other hand, five different POX isozyme bands were determined in all treatments. Enhanced peroxidation of lipid membranes under salt stress conditions was reduced by pretreatment with mannitol. We suggest that exogenous application of mannitol could alleviate salt-induced oxidative damage by enhancing antioxidant enzyme activities in the roots of salt-sensitive Kızıltan-91.     

Effect of salt and drought stress on antioxidant enzymes activities and SOD isoenzymes of liquorice (Glycyrrhiza uralensis Fisch)

The effects of salinity and drought on the antioxidative system (SOD, POD, CAT) were studied in liquorice seedlings (Glycyrrhiza uralensis Fisch). The results showed that both salt and drought stresses could induce oxidative stress, as indicated by the increase level of lipid peroxidation. The activities of SOD and POD were up-regulated by salt and drought stress, while CAT activity decreased. An additional MnSOD isoenzyme was detected in liquorice subjected to 2%NaCl stress. The data also showed that although the activity of SOD was differentially influenced by drought and salinity, the changes of antioxidant enzyme activities subjected to drought stress follow a pattern similar to that subjected to salt stress, indicating that similar defensive systems might be involved in the oxidative stress injury in liquorice.     

Effects of 24-epibrassinolide on seed germination, seedling growth, lipid peroxidation, proline content and antioxidative system of rice (Oryza sativa L.) under salinity stress

The effects of 24-epibrassinolide (24-epiBL) on seedling growth, antioxidative system, lipid peroxidation, proline and soluble protein content were investigated in seedlings of the salt-sensitive rice cultivar IR-28. Seedling growth of rice plants was improved by 24-epiBL treatment under salt stress conditions. When seedlings treated with 24-epiBL were subjected to 120 mM NaCl stress, the activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6) and glutathione reductase (EC 1.6.4.2) did not show significant difference, whereas the activity of ascorbate peroxidase (EC 1.11.1.11) significantly increased. Increased activity of peroxidase (EC 1.11.1.7) under NaCl stress showed remarkable decrease in the 24-epiBL+NaCl-applied group. Lipid peroxidation level significantly increased under salt stress but decreased with 24-epiBL application revealing that less oxidative damage occurred in this group (24-epiBL+NaCl). In addition, increased proline content in the NaCl-applied group was decreased by 24-epiBL application in the 24-epiBL+NaCl-applied group. Soluble protein content was increased by 24-epiBL application even under NaCl stress, being also higher than control conditions (no 24-epiBL or NaCl treatment). 24-epiBL treatment considerably alleviated oxidative damage that occurred under NaCl-stressed conditions and improved seedling growth in part under salt stress in sensitive IR-28 seedlings.     

NaCl胁迫对西瓜嫁接苗叶片抗氧化酶活性及光合特性的影响

以耐盐性较强的葫芦品种‘超丰抗生王’为砧木,耐盐性较弱的西瓜品种‘秀丽’为接穗,采用营养液水培法,研究了NaCl胁迫对西瓜自根苗和嫁接苗保护酶活性、膜质过氧化及光合特性的影响。结果表明,NaCl胁迫下,嫁接苗和自根苗生物量显著下降,但嫁接苗下降幅度小于自根苗;NaCl胁迫抑制了西瓜自根苗和嫁接苗的气体交换参数,但是嫁接苗的净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)及叶绿素含量显著高于自根苗;NaCl胁迫下西瓜嫁接苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均显著高于自根苗,丙二醛含量较自根苗低。上述结果表明,NaCl胁迫下嫁接苗通过维持较高的抗氧化酶活性来提高清除活性氧(ROS)的能力,从而降低氧化损伤,并保持较高光合速率,从而增强西瓜幼苗对盐胁迫的耐性。     

Paraquat pre-treatment increases activities of antioxidant enzymes and reduces lipid peroxidation in salt-stressed cucumber leaves

To investigate whether paraquat (PQ) is involved in regulation of antioxidant enzymes and lipid peroxidation under short-term salt stress, and to elucidate the physiological mechanism of salt stress mitigated by PQ, a cucumber cultivar (cv. Chunguang no. 2) was exposed to 100 mM NaCl for 48 h after pre-treatment with 10 μM PQ for 1 h. When compared to the control, salt stress increased the levels of malonaldehyde (MDA), superoxide radical (O₂^·−) and hydrogen peroxide (H₂O₂) and the activities of antioxidant enzymes, such as superoxide dismutase (EC 1.15.1.1), ascorbate peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2) in the cucumber leaves. Under salt conditions, PQ pre-treatment prevented oxidative stress as observed by the decreases in MDA, H₂O₂ and O₂^·− that correlated with the increase in antioxidant defenses. We propose that, at low concentrations, the PQ pre-treatment can reduce the salt-induced oxidative damage by increasing the antioxidative mechanisms in cucumber plants.     

丛枝菌根真菌对盐胁迫下黄瓜幼苗渗透调节物质含量和抗氧化酶活性的影响

以盐敏感型黄瓜品种‘津春2号’为材料,研究了丛枝菌根真菌(AMF)对盐胁迫下黄瓜幼苗生长及叶片、根系中渗透调节物质含量和抗氧化酶活性的影响.结果表明:(1)在盐胁迫条件下,黄瓜幼苗生长受到明显抑制,其株高、地上部、地下部干鲜重均明显减小,同时体内可溶性蛋白、可溶性糖、脯氨酸和MDA含量,以及O2(÷)产生速率和SOD、POD、CAT活性均比对照显著升高.(2)盐胁迫下接种AMF可显著促进黄瓜植株的生长,进一步提高黄瓜幼苗体内可溶性蛋白、可溶性糖和脯氨酸含量及SOD、POD、CAT活性,而显著降低MDA含量和O2(÷)产生速率.研究表明,AMF可通过显著促进盐胁迫下黄瓜幼苗体内渗透调节物质积累和抗氧化酶活性提高,有效降低体内膜脂过氧化水平,从而缓解盐胁迫对植株的伤害,增强黄瓜幼苗对盐胁迫的耐性.     

Effects of Selenium on Wheat Seedlings Under Drought Stress

The paper reports the effects of selenium (Se) supply on growth and some physiological traits of wheat (Triticum aestivum L. cv Shijiazhuang NO. 8) seedlings exposed to drought stress. The growth and physiological responses of seedlings were different depending on the Se concentration. The higher (3.0 mg Se kg⁻¹) and lower amount used (0.5 mg Se kg⁻¹) did not significantly affect on biomass accumulation. Treatments with 1.0 and 2.0 mg Se kg⁻¹ promoted biomass accumulation of wheat seedlings. Treatments at 1.0, 2.0, and 3.0 mg Se kg⁻¹ significantly increased root activity, proline content, peroxidase (POD), and catalase (CAT) activities, carotenoids (Car) content, chlorophyll content, and reduced malondialdehyde (MDA) content of wheat seedlings. Lower Se treatment did not significantly effect on chlorophyll content and MDA content, although it also increased some antioxidant index (proline and Car content, POD and CAT activities) in wheat seedlings. These results suggest that optimal Se supply is favorable for growth of wheat seedlings during drought condition.     

Mammalian sex hormones stimulate antioxidant system and enhance growth of chickpea plants

In the present study, it was aimed to investigate the influence of exogenous mammalian sex hormones (MSH) (progesterone, β-estradiol and androsterone) on the morphological (root and shoot growth) and biochemical parameters (protein and sugar content, antioxidant enzyme activities, and lipid peroxidation and H₂O₂ levels) of chickpea (Cicer arietinum L.) plants growing under control conditions. The solutions of hormones prepared at different concentrations (10⁻⁴, 10⁻⁶, 10⁻⁹, 10⁻¹² and 10⁻¹⁵ M) were sprayed once on the leaves of 7-day plants. The plants were harvested on 18 days after the hormone treatment. Although all of the hormones at the tested concentrations significantly increased plant growth, soluble protein and sugar contents, and antioxidant enzyme activities [superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT)], they decreased H₂O₂ content and lipid peroxidation level when compared with control plants. The activities of SOD, POX and CAT reached to the highest levels at 10⁻⁶ M for progesterone, and 10⁻⁹ M for β-estradiol and androsterone, which maximum growth, protein and sugar contents were determined. The same concentrations also resulted in the lowest levels for H₂O₂ content and lipid peroxidation. It can be interpreted that the MSH improve plant growth and development by affecting some biochemical parameters including antioxidative system.     

Enhancing effects of 24-epibrassinolide and Putrescine on the antioxidant capacity and free radical scavenging activity of <Emphasis Type="Italic">Raphanus sativus</Emphasis> seedlings under Cu ion stress

The present investigation recorded significant restoration of seedling growth (root length, shoot length and fresh weight) upon application of 24-epibrassinolide (EBL) and putrescine (Put) to 7-day-old seedlings of Raphanus sativus L. cv. Pusa chetki grown under copper (Cu) ion stress. EBL and Put with/or without Cu ion treated seedlings showed increased titers of ascorbic acid, total phenols and proline when compared with Cu-stressed seedlings. Differential responses in the activities of guaiacol peroxidase (GPOX) and catalase (CAT) were noted for EBL and Put alone or with/or without Cu ion treatment. Decreased activities of glutathione reductase (GR) and superoxide dismutase (SOD) noted for EBL and Put alone were observed to enhance significantly when applied in combination with Cu ion solution. A remarkable decrease in malondialdehyde contents was observed in seedlings treated with EBL and Put alone and with/or without Cu ion stress. Enhanced free radical scavenging activities were also recorded for seedlings given EBL and Put alone or in combination over Cu ion stressed seedlings. Maximum DPPH activity was observed in seedlings treated with Put and EBL 10⁻⁹ M + Put. Significant enhancements in deoxyribose and reducing power activities were too recorded for Put, EBL and Put + 10⁻⁹ M EBL treatments. Improved seedling growth, antioxidant levels (ascorbic acid, total phenols and proline) and enzymic (GPOX, CAT, SOD and GR) activities and free radical scavenging capacities along with reduced membrane damage in seedlings given EBL and Put with/or without Cu stress suggests significant and positive interactions of EBL and Put in alleviating the Cu ion induced oxidative damage in radish seedlings.     

Exogenous application of penconazole regulates plant growth and antioxidative responses in salt-stressed Mentha pulegium L.

The mechanism of growth amelioration in salt-stressed pennyroyal (Mentha pulegium L.) was investigated by exogenous application of penconazole (PEN). Seven weeks after sowing, seedlings were treated with increasing NaCl concentrations (0, 25, 50, and 75 mM) with or without PEN (15 mg l^?1) and were harvested randomly at different times. Results showed that some growth parameters and the relative water content (RWC) decreased under salt stress, while lipid peroxidation, H₂O₂ content, activities of superoxide dismutase (SOD; EC 1.15.1.1), peroxidase (POX; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.10.3.1), catalase (CAT; EC 1.11.1.6), and ascorbate peroxidase (APX; EC 1.11.1.1) remarkably increased. Exogenous application of PEN increased some growth parameters, RWC, antioxidant enzyme activities, and H₂O₂ content, but the effects of PEN were more significant under salt stress conditions. PEN treatment also decreased lipid peroxidation. These results suggest that PEN-induced tolerance to salt stress in M. pulegium plants may be related to regulation of antioxidative responses and H₂O₂ level.     

Influence of a Brassinosteroid Analogue on Antioxidant Enzymes in Rice Grown in Culture Medium with NaCl

We studied the effects of a polyhydroxylated spirostanic brassinosteroid analogue (BB-16) on the activities of antioxidant enzymes in rice seedlings grown in vitro in culture medium supplemented with NaCl. Seedlings were grown in medium with 75 mM NaCl and 0.001 or 0.01 mg dm⁻³ BB-16 for 16 d or 3-d-old seedlings were exposed for 4 d to 0, 0.001 or 0.01 mg dm⁻³ BB-16 then further grown in medium with 75 mM NaCl without BB-16. Seedlings exposed to 0.01 mg dm⁻³ BB-16 for 16 d showed significant increase in the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR) and a slight increase in ascorbate peroxidase (APX). On the other hand, 4-d exposure to BB-16 only increased SOD and CAT activities at concentration 0.001 mg dm⁻³. GR activity was not altered by this BB-16 treatment. These results indicated that BB-16, which is structurally modified in the lateral chain in relation to natural brassinosteroids, changes the activity of key antioxidant enzymes, which might confer tolerance to saline stress. This revised version was published online in July 2006 with corrections to the Cover Date.     

外源水杨酸对NaCl胁迫下大豆种子萌发和幼苗生长生理的影响

以大豆种子、幼苗为试验材料,采用砂培的方法,研究了0.2mmol·L-1外源水杨酸(SA)对100mmol·L-1 NaCl胁迫下大豆种子萌发、幼苗形态及生物量、膜脂过氧化和抗氧化酶活性的影响。结果显示:NaCl胁迫下,大豆种子萌发和幼苗生长受到显著抑制,且随着胁迫时间的延长(0~3d),大豆幼苗相对电解质渗漏率、硫代巴比妥酸活性产物(TBARS)含量显著升高,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性均明显降低。外源SA促进NaCl胁迫下大豆种子萌发和根茎生长,增加幼苗生物量积累,降低幼苗叶片相对电解质渗漏率和TBARS含量,增强其叶片SOD、CAT、APX活性。研究表明,NaCl胁迫能显著抑制大豆种子萌发和幼苗生长,而一定浓度的外源SA能有效提高NaCl胁迫下大豆种子活力及幼苗抗氧化酶活性,减轻膜脂过氧化程度,缓解NaCl胁迫所造成的伤害,提高大豆幼苗抗盐胁迫的能力。     

Effect of salt stress on physiological and antioxidative responses in two species of <Emphasis Type="Italic">Salicornia</Emphasis> (<Emphasis Type="Italic">S. persica</Emphasis> and <Emphasis Type="Italic">S. europaea</Emphasis>)

The effects of salt stress on growth parameters, free proline content, ion accumulation, lipid peroxidation, and several antioxidative enzymes activities were investigated in S. persica and S. europaea. The seedlings were grown for 2 months in half-strength Hoagland solution and treated with different concentrations of NaCl (0, 85, 170, 340, and 510 mM) for 21 days. The fresh and dry weights of both species increased significantly at 85 and 170 mM NaCl and decreased at higher concentrations. Salinity increased proline content in both the species as compared to that of control. Sodium (Na⁺) content in roots and shoots increased, whereas K⁺ and P_i content in both organs decreased. At all NaCl concentrations, the total amounts of Na⁺ and K⁺ were higher in shoots than in roots. Malondialdehyde (MDA) content declined at moderate NaCl concentrations (85 and 170 mM) and increased at higher levels. With increased salinity, superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPX) activities also increased gradually in both species. In addition, it seems that GPX, CAT, and SOD activities play an essential protective role in the scavenging reactive oxygen species (ROS) in both species. Native polyacrylamide gel electrophoresis (PAGE) indicated different isoform profiles between S. persica and S. europaea concerning antioxidant enzymes. These results showed that S. persica exhibits a better protection mechanism against oxidative damage and it is more salt-tolerant than S. europaea possibly by maintaining and/or increasing growth parameters, ion accumulation, and antioxidant enzyme activities.     

28-Homobrassinolide potential for oxidative interface in <Emphasis Type="Italic">Brassica juncea</Emphasis> under temperature stress

Exploration of scavenging potential of 28-homobrassinolide (28-homoBL) in mitigating the oxidative stress caused by free radicals (·O₂ ^?, H₂O₂, ·NO, OH^?) produced due to temperature stress (4, 44 °C) in Brassica juncea L. was made in the present research. Brassica juncea var. RLC-1 seeds were given pre-sowing soaking of different concentrations of 10^?9 M 28-homoBL for 8 h. Seeds were sown in bedded petri plates lined with 10 No. What’s man filter paper under controlled laboratory conditions. Temperature of 4 and 44 °C, taken as low- and high-temperature stress, suppressed membrane stability and overall growth of the seedlings, while cell death was triggered. Accumulation of malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and nitric oxide (NO) was boosted which resulted in enhanced oxidative stress on the 10th day after sowing. Activity level of antioxidant enzymes viz. superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPOX), and ascorbate peroxidase (APOX) was enhanced which was ensued for up-regulation of total antioxidant potential in 10-day-old plants exposed to negative effect of temperature stress. Priming treatment of 28-homoBL at seed level helped in maintaining the growth of seedlings to higher level as compared to only stressed as well as from control double distilled water-raised seedlings. 10^?9 M 28-HBL found to be the best in enhancing the enzymatic activities of SOD, CAT, GPOX, and APOX and thus maintained antioxidant potential at higher level which accounted for alleviating oxidative stress caused due to extreme temperature stress. Dead cell formation reduced significantly in 28-homoBL-treated plants, membrane stability was upturned, while production of MDA, H₂O_2, and NO was under control. These results suggested and try to establish 28-homoBL as effective stress protector for B. juncea particularly from the oxidative damage induced by extreme temperatures.     

The effect of NaCl on antioxidant enzyme activities in potato seedlings

The effect of NaCl on the growth and activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were investigated in the seedlings of four potato cultivars (Agria, Kennebec; relatively salt tolerant, Diamant and Ajax; relatively salt sensitive). The shoot fresh mass of Agria and Kennebec did not changed at 50 mM NaCl, whereas in Diamant and Ajax it decreased to 50 % of that in the controls. In Agria and Kennebec, SOD activity increased at 50 mM NaCl, but no significant changes observed in Diamant and Ajax. At higher NaCl concentration, SOD activity reduced in all cultivars. CAT and POD activities increased in all cultivars under salt stress. Unlike the other cultivars, in Ajax seedlings, APX activity increased in response to NaCl stress. We also observed new POD and SOD isoenzyme activities and changes in isoenzyme compositions under salt stress. These results suggest that salt-tolerant potato cultivars may have a better protection against reactive oxygen species (ROS) by increasing the activity of antioxidant enzymes (especially SOD) under salt stress.     

Effects of cytokinin on callus proliferation associated with physiological and biochemical changes in <Emphasis Type="Italic">Vitis vinifera</Emphasis> L.

The essential role of 6-benzylaminopurine (BA) in plant tissue culture has been widely known; however, physiological and biochemical mechanisms behind BA requirement have not been fully understood yet. BA may have an important role on callus growth by regulating antioxidant enzyme activities and acting as an effective free radical scavenger. To test this hypothesis, the impact of exogenous BA concentrations on antioxidative system in Vitis vinifera L. cv. ‘Bogazkere’ callus was investigated under in vitro conditions. Relative fresh weight growth (RFWG) of calli, total phenolics (TP) content, endogenous hydrogen peroxide (H₂O₂), malondialdehyde (MDA), proline concentrations, percentage of electrolyte leakage (EL), and some of the antioxidant enzyme activities; such as superoxide dismutase (SOD), and guaiacol peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) were measured. Inhibitory effect of high concentrations of BA on antioxidant enzyme activities and RFWG was found. In the presence of BA at 0.1 mg L⁻¹, SOD, POD, and APX activities decreased, while CAT activity increased in comparison with the controls. Exogenous BA treatments higher than 0.1 mg L⁻¹ resulted in an increase in cellular TP, H₂O₂, MDA, proline contents, and percentage of EL, while RFWG of calli decreased. Based on the findings, it may be concluded that only 0.1 mg L⁻¹ BA concentration combined with NAA could play a direct role in reducing the level of free radicals and phenolic production associated with proliferation capacity of grape cells under in vitro conditions. Furthermore, cytokinin was effective in the antioxidative enzyme system, lipid peroxidation, and electrolyte leakage.     

Comparison of resistance to drought of three bean cultivars

The aim of the present work was to evaluate oxidative stress and plant antioxidant system of three contrasting bean (Phaseolus vulgaris L.) genotypes in the response to drought. Drought was imposed 14 d after emergence, by withholding water, until leaf relative water content reached 65 %. Water stress increased lipid peroxidation (LPO), membrane injury index, H₂O₂ and OH^⋅ production in leaves of stressed plants. Activities of the antioxidative enzymes superoxide dismutase (SOD) and ascorbate peroxidase (APOX) increased significantly under water stress in all the studied cultivars, while catalase (CAT) increased in cvs. Plovdiv 10 and Prelom, but decreased in cv. Dobrudjanski ran. Furthermore cv. Plovdiv 10 which had the highest APOX and CAT activities also showed the lowest increase in H₂O₂ and OH^⋅ production and LPO while cv. Dobrudjanski ran showed the lowest increases (and often the lowest values) in the antioxidant enzyme activities and the highest increases of H₂O₂ and OH^⋅ production, and LPO. On the basis of the data obtained we could specify cv. Plovdiv 10 and cv. Prelom as drought tolerant and cv. Dobrudjanski ran as a drought sensitive.     

外源GSH对盐胁迫下番茄幼苗生长及抗逆生理指标的影响

采用营养液栽培法,研究外源谷胱甘肽(GSH)对NaCl胁迫下番茄幼苗生长、根系活力、电解质渗透率和丙二醛(MDA)、脯氨酸(Pro)、可溶性糖含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的影响,为利用外源物质减轻盐胁迫伤害提供理论依据。结果显示:(1)NaCl胁迫显著抑制了番茄幼苗的生长、根系活力和SOD、POD、CAT活性,提高了电解质渗透率及MDA、Pro、可溶性糖含量;(2)外源喷施GSH能够诱导NaCl胁迫下番茄幼苗叶片抗氧化酶SOD、POD、CAT活性上调,电解质渗透率及MDA含量下降,Pro和可溶性糖含量恢复至对照水平;(3)外源喷施还原型谷胱甘肽抑制剂(BSO)使NaCl胁迫下番茄幼苗的根系活力以及抗氧化酶SOD、POD、CAT活性下降,脯氨酸含量提高;(4)喷施GSH可诱导BSO和NaCl共处理番茄植株的根系活力、SOD、POD、CAT活性提高,MDA和Pro含量降低。研究表明,外源GSH可通过提高促进盐胁迫下番茄幼苗植株渗透调节能力及清除活性氧的酶促系统的防御能力、降低细胞膜脂过氧化程度、保护膜结构的完整性,从而有效缓解NaCl胁迫对番茄幼苗生长的抑制,提高其耐盐性。