水杨酸对水分胁迫黄瓜幼苗叶片生理过程的影响

研究了外源水杨酸(salicylic acid,SA)对水分胁迫下黄瓜幼苗叶片主要生理过程的影响。1mmol／L的SA处理黄瓜幼苗24h后,叶片中POD活性剧增,SOD活性增加不明显,H2O2清除酶CAT和APX活性受抑制,H2O2含量上升引起膜脂过氧化产物MDA含量上升,造成轻度氧化胁迫;在随后水分胁迫过程中,经SA预处理积累的H2O2诱导APX和CAT活性上升并清除产生的H2O2;SA预处理后,叶片中Rubisco含量及其基因转录水平明显高于对照,光合作用受影响较小。这表明SA使黄瓜幼苗生理活性有较大改善,增强了植株对水分胁迫的抗性。     

水杨酸提高香蕉幼苗的抗冷性与H2O2代谢有关

探讨了水杨酸(salicylic acid, SA)提高香蕉幼苗抗冷性的可能机理.在常温下(30/22 ℃)用不同浓度(0～3.5 mmol/L)的SA水溶液喷洒叶片1 d,置于7 ℃低温下冷胁迫3 d,随后于常温下恢复2 d后测定电解质泄漏率,结果表明:SA 0.3～0.9 mmol/L能显著提高香蕉幼苗的抗冷性,以0.5 mmol/L效果最佳.若把冷胁迫温度降到5 ℃,SA 0.5 mmol/L 预处理可显著减少幼苗叶片的萎蔫面积.但当SA浓度高于1.5 mmol/L时,恢复期间的电解质泄漏甚至高于对照(蒸馏水处理),表明它们加剧了冷害.SA提高香蕉幼苗的抗冷性可能需要H2O2的参与:1)SA 0.5 mmol/L常温处理诱导了H2O2的积累和活性氧造成的膜脂过氧化--三氯乙酸反应物质(TBARS)的增加,这可能与H2O2的清除酶--过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性的受抑和H2O2的产生酶-超氧化物歧化酶(SOD)活性几乎不受影响有关;2)外源H2O2(1.5～2.5 mmol/L)也能显著降低低温胁迫期间的电解质泄漏,表明也能提高抗冷性;3)而用H2O2的捕捉剂--二甲基硫脲(DMTU)可明显抑制SA诱导的抗冷性;4)在低温胁迫与恢复期间,SA预处理明显提高了CAT和APX的活性,抑制了H2O2与TBARS的快速上升.     

水杨酸提高香蕉幼苗的抗冷性与H2O2代谢有关

探讨了水杨酸(salicylic acid,SA)提高香蕉幼苗抗冷性的可能机理。在常温下(30／22℃)用不同浓度(0—3．5mmol／L)的SA水溶液喷洒叶片1d,置于7℃低温下冷胁迫3d,随后于常温下恢复2d后测定电解质泄漏率,结果表明：SA0．3～0．9mmol／L能显著提高香蕉幼苗的抗冷性,以0．5mmol／L效果最佳。若把冷胁迫温度降到5℃,SA0．5mmol／L预处理可显著减少幼苗叶片的萎蔫面积。但当SA浓度高于1．5mmol／L时,恢复期间的电解质泄漏甚至高于对照(蒸馏水处理),表明它们加剧了冷害。SA提高香蕉幼苗的抗冷性可能需要H2O2的参与：1)SA0．5mmol／L常温处理诱导了H2O2的积累和活性氧造成的膜脂过氧化——三氯乙酸反应物质(TBARS)的增加,这可能与H2O2的清除酶——过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性的受抑和H2O2的产生酶—超氧化物歧化酶(SOD)活性几乎不受影响有关;2)外源H2O2(1．5—2．5mmoL／L)也能显著降低低温胁迫期间的电解质泄漏,表明也能提高抗冷性;3)而用H2O2的捕捉剂——二甲基硫脲(DMTU)可明显抑制SA诱导的抗冷性;4)在低温胁迫与恢复期间,SA预处理明显提高了CAT和APX的活性,抑制了H2O2与TBARS的快速上升。     

钙对根际低氧胁迫下黄瓜幼苗活性氧代谢的影响

采用营养液栽培系统,以黄瓜品种中农8号为材料,研究了Ca2 对根际低氧胁迫下黄瓜幼苗体内超氧阴离子(O2?-)、过氧化氢(H2O2)、丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱苷肽还原酶(GR)活性的影响.结果表明:低氧胁迫下黄瓜体内活性氧含量和保护酶活性均高于对照;低氧缺钙处理的活性氧含量最高,而保护酶活性却较低;营养液Ca2 浓度提高到8mmol/L后,显著降低了低氧胁迫下黄瓜幼苗体内MDA、H2O2含量和O?2-产生速率,提高了SOD、POD、CAT、APX、GR活性,说明Ca2 可减少低氧胁迫下黄瓜幼苗体内活性氧的产生,提高抗氧化酶的活性、降低膜脂过氧化水平,减缓低氧胁迫对植株的伤害,增强黄瓜幼苗对低氧逆境的适应性.     

CO_2激光预处理对PEG6000胁迫下小麦幼苗根中抗氧化酶活性的影响

用CO2激光对小麦种子分别辐照0、1、3、5min,待其生长至12d时,用10%(W/V)PEG6000胁迫其幼苗,研究激光预处理对PEG6000水分胁迫下小麦幼苗根部脂质过氧化伤害的防护作用。结果表明,CO2激光预处理3min可使水分胁迫的小麦幼苗根部MDA、H2O2含量和O2.-产生速率显著降低(P0.05),可显著提高(P0.05)小麦幼苗根部SOD、POD、CAT、APX活性和根长、根干重。激光预处理3min可抑制由水分胁迫引起的小麦幼苗根部脂质过氧化作用。     

CO2激光预处理对PEG6000胁迫下小麦幼苗根中抗氧化酶活性的影响

用CO2激光对小麦种子分别辐照0、1、3、5min,待其生长至12d时,用10%（W/V）PEG6000胁迫其幼苗,研究激光预处理对PEG6000水分胁迫下小麦幼苗根部脂质过氧化伤害的防护作用。结果表明,CO2激光预处理3min可使水分胁迫的小麦幼苗根部MDA、H2O2含量和O2.-产生速率显著降低（P〈0.05）,可显著提高（P〈0.05）小麦幼苗根部SOD、POD、CAT、APX活性和根长、根干重。激光预处理3min可抑制由水分胁迫引起的小麦幼苗根部脂质过氧化作用。     

镉胁迫下绿豆和箭舌豌豆幼苗的抗氧化反应

采用溶液培养法对Cd2 胁迫下绿豆和箭舌豌豆幼苗叶组织内的抗氧化酶活性、活性氧和丙二醛(MDA)含量以及细胞电解质泄漏率的变化进行了研究。结果显示,随着Cd2 胁迫浓度的增加和胁迫时间的延长,2种作物叶组织内的MDA含量和细胞电解质泄漏率明显增加;在胁迫期间,二者的过氧化氢(H2O2)和超氧阴离子(O2.-)的含量以及过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、超氧化物歧化酶(SOD)活性呈先升高并在不同的时间达到高峰后再下降的趋势。与箭舌豌豆相比,Cd2 胁迫下的绿豆幼苗叶组织的MDA含量、电解质泄漏率及H2O2和O2.-的积累量较高,CAT、SOD和APX的活性较低。研究表明,Cd2 胁迫下箭舌豌豆的抗氧化能力高于绿豆的抗氧化能力。     

氯化胆碱对盐胁迫黄瓜幼苗渗透调节物质及活性氧代谢系统的影响

以盐敏感型黄瓜品种津春4号为材料,采用水培方法研究了叶面喷施不同浓度(0.5、1.0和1.5 mmol·L-1)氯化胆碱(CC)对NaCl胁迫(75 mmol·L-1)下黄瓜幼苗鲜重、叶片叶绿素、渗透调节物质含量及活性氧代谢系统的影响.结果表明:(1)单独CC处理可提高黄瓜叶片的叶绿素、可溶性糖和可溶性蛋白含量以及过氧化氢酶(CAT)与过氧化物酶(POD)活性,降低O2·-产生速率,但对植株鲜重及超氧化物岐化酶(SOD)活性影响不大;(2)NaCl胁迫处理增加了黄瓜幼苗叶片中可溶性糖和可溶性蛋白含量,增强了SOD、POD和CAT活性,提高了O2·-产生速率及丙二醛(MDA)的含量,但同时降低了叶绿素含量与植株鲜重;(3)盐胁迫前CC预处理可缓解黄瓜幼苗叶绿素含量和植株鲜重的下降、以及MDA含量和O2·-产生速率的上升趋势,且进一步提高了盐胁迫下黄瓜叶片中SOD、POD和CAT活性.因此,适宜浓度的氯化胆碱可显著提高盐胁迫下黄瓜叶片的抗氧化酶活性,提高清除活性氧的能力,缓解盐胁迫对黄瓜幼苗细胞膜的伤害,增强黄瓜幼苗的耐盐性.     

水分胁迫下自由基清除剂对番木瓜的生理保护效应

用维他命C(Vc)、维他命E(VE)和苯甲酸钠等作为外源自由基清除剂在水分胁迫前1d预处理番木瓜幼苗,研究其对番木瓜的生理保护效应。结果表明,3种外源自由基清除剂预处理有效地降低了水分胁迫下番木瓜叶片细胞质膜透性、POD活性、MDA和H2O2含量的上升程度,并能延缓叶片叶绿素和可溶性蛋白质含量和SOD活性的降低。外源自由基清除剂通过有效清除H2O2降低膜脂过氧化程度,从而减轻水分胁迫对番木瓜引起的自由基伤害和提高番木瓜的抗旱能力。不同自由基清除剂预处理对番木瓜的抗旱保护效果存在差异,其中以Vc预处理的保护效果最好。     

H2O2胁迫锻炼对小麦幼苗抗旱性的影响

12 d龄的春小麦幼苗在1 mmol·L-1 及10 mmol·L-1 H2O2的胁迫锻炼过程中,质膜透性增大,O-·及H2O2含量增多,CAT活性升高,叶绿素含量降低,低浓度H2O2胁迫使SOD活性上升,高浓度时却使其活性下降.经过H2O2胁迫锻炼后的小麦遭受干旱胁迫时,叶绿素含量、SOD活性、CAT活性均高于对照组,而质膜透性、O-·及H2O2含量却低于对照组.表明H2O2胁迫锻炼,提高了小麦幼苗的抗氧化能力,增强了其抗旱性.     

低温胁迫对巨尾桉幼苗膜脂过氧化及保护酶的影响

以木本植物巨尾桉幼苗为材料 ,研究低温胁迫对巨尾桉膜脂过氧化及保护酶的影响 ,测定了幼苗叶片的O 2(超氧阴离子 )产生速率、H2 O2 、(过氧化氢 )、MDA(丙二醛 )含量、相对电导率和SOD(超氧化物歧化酶 )、POD(过氧化物酶 )、CAT(过氧化氢酶 )、APX(抗坏血酸过氧化物酶 )活性。结果表明 :低温胁迫使叶片O 2 产生速率、H2 O2 、MDA含量和相对电导率增加 ,但抗寒锻炼植株的增幅远小于对照 ;抗寒锻炼植株的SOD、POD、CAT和APX活性均低于对照。     

苯丙氨酸解氨酶在诱导黄瓜幼苗抗寒性中的作用

为了探讨苯丙氨酸解氨酶(PAL)在诱导黄瓜幼苗抗寒性中的作用,采用喷施特异抑制剂(AOPP)的方法控制PAL活性,测定幼苗抗寒性的变化.结果表明： 低温可以诱导黄瓜幼苗叶片中PAL的基因表达和活性升高;喷施AOPP显著抑制了叶片中PAL活性,减少了酚类和类黄酮物质的积累.低温对黄瓜幼苗造成显著伤害,AOPP预处理加剧了低温对幼苗的损伤,幼苗抗寒性降低.与对照相比,幼苗叶片中相对电解质渗漏率和丙二醛(MDA)含量显著升高,PSII最大光化学效率(F_v/F_m)降低,光化学猝灭参数Y(NO)升高,胁迫相关基因(PR1-1a、COR47、P5CS、HSP70)的诱导表达受到抑制.低温导致黄瓜幼苗叶片中H₂O₂积累,还原型抗坏血酸(AsA)含量降低,脱氢抗坏血酸(DHA)含量升高,AsA∶DHA减小;喷施AOPP的幼苗中抗氧化酶(过氧化氢酶CAT、抗坏血酸过氧化物酶APX)活性显著低于对照,H₂O₂过量积累,AsA∶DHA更低.施用H₂O₂清除剂可以有效缓解喷施AOPP引起的低温损伤加剧,而施用CAT抑制剂的幼苗对低温胁迫更敏感.表明低温诱导了PAL活性升高,促进了苯丙烷类次生代谢产物的合成,提高了胞内抗氧化酶活性,可有效清除活性氧分子,维持AsA氧化还原状态,缓解低温引起的光损伤和氧化损伤.     

Thermotolerance and antioxidant response induced by heat acclimation in <Emphasis Type="Italic">Freesia</Emphasis> seedlings

Followed a heat acclimation pretreatment, seedlings of Freesia hybrida ‘Shangnong Jinghuanghou’ were exposed to heat stress at 38°C for 6 h treatment and then recovered at 22°C for 72 h to study the impact of heat acclimation (30°C) on thermotolerance under heat stress. The results showed that the pretreated seedlings performed better under heat stress than control. Heat acclimation could slow down the decrease of chlorophyll contents under heat stress and recover better. Higher levels of soluble sugar and proline and slight lower level of soluble protein were observed in pretreated seedlings. After recovery, similar levels of proline and soluble protein were maintained in all seedlings. However, a higher level of soluble sugar was maintained in pretreated seedlings. MDA content and EL showed a stable level in pretreated seedlings while a significant increase in control, followed by a significant decrease after recovery. Significant different responses of SOD, POD, CAT, and APX activities were observed in pretreated seedlings and control. Heat acclimation led to higher activities of these enzymes and a significant response of antioxidant enzyme activities occurred in a time-dependent manner under heat stress. Exposure to high temperature caused a significant increase in SOD and APX activity, and much higher levels in SOD and APX activity were observed in pretreated seedlings compared to control during heat stress. A slight difference in change pattern of POD and CAT activity was presented. The highest activities of POD and CAT were observed at 4 and 6 h of heat stress in pretreated seedlings and control, respectively. After 72 h recovery, the activities of all tested enzymes decreased to similar levels in all seedlings.     

Participation of H2O2 in Enhancement of Cold Chilling by Salicylic Acid in Banana Seedlings

The possible physiological mechanism of enhancement of cold tolerance by salicylic acid (SA) in banana seedlings (Musa acuminata cv. Williams 8188) was explored. Measurements of leakage electrolyte after 2 d of recovery at 30/22 ℃ (day/night) following 3 d of cold stress at 7 ℃ showed that pretreatment with hydroponic solution containing SA 0.3－0.9 mmol/L as foliar spray under normal growth conditions (30/22 ℃) could significantly enhance cold tolerance of banana plants. The highest enhancing effect of SA occurred at 0.5 mmol/L and it showed the lowest leakage rate of electrolyte or smaller leaf wilting area after 2 d of recovery at normal temperature from 3 d of 7 ℃ or 5 ℃ cold stress. Higher concentrations (≥2.5 mmol/L) of SA, however, caused more electrolyte leakage, indicating that they aggravated chilling damage. Enhanced cold tolerance by SA could be related to H2O2 metabolism. Compared with water-treated seedlings (control), SA 0.5 mmol/L treatment inhibited activities of catalase (CAT) and ascorbate peroxidase (APX), increased peroxidase (POX) activity, but did not affect the activity of superoxide dismutase (SOD) under normal growth conditions, and these changes might lead to an accumulation of H2O2, whereas SA pretreatment enhanced the activities of CAT and APX, and reduced the increase in productions of H2O2 and thiobarbituric acid-reaction substances (TBARS) during subsequent 7 ℃ cold stress and recovery periods. Exogenous H2O2 treatments (1.5－2.5 mmol/L) also increased cold tolerance of banana seedlings. Furthermore, pretreatment of banana seedlings with dimethylthiourea (a trap for H2O2) significantly inhibited cold tolerance induced by SA. These results suggested that endogenous H2O2 may be required for SA-enhanced cold tolerance. The significance of the interaction of SA, H2O2 and H2O2-metabolizing enzymes during cold stress has been discussed.     

O_3与CO_2浓度倍增对油松针叶抗氧化酶活性的影响

以4年生的油松幼苗为试材,采用开顶箱内气体熏蒸实验,对经高浓度O_3(80nmol·mol~(-1))和CO_2(700 μmol·mol~(-1))单一及复合处理3年后,油松当年生针叶内丙二醛(MDA)含量、活性氧自由基和抗氧化酶等逆境生理指标进行了分析.结果表明:超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)和脱氢抗坏血酸还原酶(DHAR)活性经O_3处理后显著升高,分别比对照上升了43.1%、18.9%、283.5%和142.6%,而CO_2和复合处理仅对APX和CAT活性有明显的诱导作用,但均低于O_3处理;O_3处理导致MDA含量上升51.8%,而外加CO_2则能有效逆转这一趋势;超氧阴离子(O_2~-·)产生速率和H_2O_2含量在所有处理组合间均无显著差异.上述结果说明,O_3能有效地激活油松当年生针叶内的抗氧化酶系统,而CO_2能缓解O_3所带来的不利影响,但并非通过提高抗氧化酶活性这一途径.

Abstract：

Four-year-old Pinus tabulaeformis seedlings were planted in open-topped chambers and treated with elevated O_3(80 nmol·mol~(-1)) and/or CO_2(700 μmol·mol~(-1)). After treated for three years, the malondialdehyde (MDA) content, reactive oxygen species, and antioxidant enzyme activities in the current year needles were analyzed. In treatment elevated O_3, the activi-ties of superoxide dismutase (SOD), aseorbate peroxidase (APX), catalase (CAT) and de-hydroaseorbate reductase (DHAR) increased significantly, being 43. 1%, 18.9%, 283.5% and 142. 6% higher than the control; and in treatments elevated CO_2 and its combination with el-evated O_3, only APX and CAT activities were induced remarkably but still lower than those in treatment elevated O_3. Elevated O_3 increased the MDA content by 51.8%, whereas the combina-tion of elevated O_3 and CO_2 reversed this increase efficiently. No significant differences were ob-served in the superoxide anion (O_2~-·) generating rate and H_2O_2 content among all treatments. All the results demonstrated that elevated O_3 was able to effectively activate the antioxidant enzyme system in P. Tabulaeformis current year needles, while elevated CO_2 could mitigate the negative effects of elevated O_3 through the actions other than enhancing the antioxidant enzyme activities.     

Effects of Different Treatments of Salicylic Acid on Heat Tolerance, Chlorophyll Fluorescence, and Antioxidant Enzyme Activity in Seedlings of Cucumis sativa L.

The effects of different treatments of salicylic acid (SA) on lipid peroxidation, chlorophyll fluorescence and antioxidant enzyme activity in seedlings of Cucumis sativa L. were studied before heat stress treatment, 36 h after heat stress and 24 h after recovery. Compared with the controls (foliar spray of distilled water), a foliar spray of 1 mM SA (SSA treatment) decreased electrolyte leakage and the concentration of H₂O₂ and thiobarbituric acid reactive substances (TBARS). SSA treatment also enhanced maximum yield of photosystem II photochemical reactions (Fv/Fm) and the quantum yield of the photosystem II electron transport (ΦPSII) after both heat stress and recovery; however, adding 1 mM SA to the nutrient solution (ASA treatment) or both adding 1 mM SA to the nutrient solution and foliar spray of 1 mM SA as well (SSA + ASA treatment) had the opposite effects. SOD activity was stimulated by all SA treatments. CAT activity was stimulated by SSA treatment and inhibited by ASA and SSA + ASA treatments after heat stress and recovery. This suggest that SSA treatment can efficiently remove H₂O₂ and decrease heat stress, and CAT plays a key role in removing H₂O₂ in cucumber seedlings under heat stress, while more H₂O₂ accumulates in ASA and SSA + ASA treatments and therefore induces serious oxidative stress. GPX, APX and GR showed higher activities in all SA treatments under heat stress, however, it appears that they were not key enzymes in removing H₂O₂ in cucumber subject to heat stress.     

外源脯氨酸对高温胁迫下黄瓜幼苗叶片AsA-GSH循环和光合荧光特性的影响

以抗热性较弱的黄瓜品种‘新泰密刺'为试材,在人工气候箱内采用营养液栽培法,研究了外源脯氨酸(Pro)预处理对高温胁迫下黄瓜幼苗叶片抗坏血酸-谷胱甘肽循环和光合荧光特性的影响.结果显示:(1)与清水处理相比,高温胁迫4 h和8 h时,Pro预处理黄瓜幼苗叶片单脱氢抗坏血酸还原酶(MDAR)活性、GSH(还原型谷胱甘肽)/GSSG(氧化型谷胱甘肽)比值及GSH含量显著升高;(2)在高温胁迫8 h时,Pro预处理幼苗的净光合速率(P_n)、气孔导度(G_s)及PSⅡ的最大光化学效率(F_v/F_m)、光化学淬灭系数(q_P)均显著升高,而蒸腾速率(T_r)和非光化学淬灭系数(NPQ)降低.研究表明,外源Pro预处理可显著提高高温胁迫下黄瓜幼苗叶片抗坏血酸-谷胱甘肽循环清除H_2O_2能力和叶片光合能力,有效缓解高温胁迫对黄瓜叶片抗氧化系统和光合系统的伤害,从而增强植株的耐热性.     

Salicylic acid increases tolerance to oxidative stress induced by hydrogen peroxide accumulation in leaves of cadmium-exposed flax (Linum usitatissimum L.)

The aim of this study is to investigate the impacts of exogenous salicylic acid (SA) pretreatments on hydrogen peroxide (H₂O₂) accumulation, protein oxidation, and H₂O₂-scavenging enzymes in leaves of Cd-treated flax seedlings. Cd-enhanced H₂O₂ levels were related to increased activities of guaiacol peroxidase (POX, EC 1.11.1.7) and ascorbate peroxidase (APX, EC 1.11.1.11), and were independent of changes in catalase (CAT, EC 1.11.1.6) and superoxide dismutase (SOD, EC 1.15.1.1) activities. In control flax seedlings, exogenous SA pretreatments inhibited the activity of CAT, resulted in an enhanced production of H₂O₂ suggesting that SA requires H₂O₂ to initiate an oxidative stress. However, although leaves of Cd-free flax seedlings pretreated with SA accumulated in vivo H₂O₂ by 1.2-fold compared with leaves of Cd-only exposed ones; the damage to growth and proteins after the exposure to Cd was significantly less, indicating that SA can regulate the Cd-induced oxidative stress. Moreover, the Cd-treated seedlings primed with SA exhibited a higher level of total antioxidant capacities and increased activities of H₂O₂-detoxifying enzymes.     

模拟酸雨和铜复合污染对白花泡桐生理特性的影响及其解毒机制

采用盆栽方法,研究了模拟酸雨(pH分别为4.0、5.0)和Cu(0～200mg·kg-1)复合污染对白花泡桐生理特性的影响及其解毒机制.结果表明:未加Cu处理时,不同酸雨处理间,白花泡桐的叶绿素、类胡萝卜素、超氧阴离子、过氧化氢和丙二醛含量均差异不显著;100和200mg·kg-1Cu处理时,pH4.0处理的叶绿素和类胡萝卜素含量显著低于,而超氧阴离子、过氧化氢和丙二醛含量显著高于pH5.0处理.Cu处理的叶绿素a/b值明显高于未加Cu处理.随着酸雨酸度增加,叶片铜含量明显减少,而根部铜含量明显增加.pH5.0时,随Cu浓度增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性均持续增强,植物络合素和谷胱甘肽(GSH)总量均明显增加;而在pH4.0时,SOD、POD、CAT和APX活性呈先升后降,而GSH总量在Cu浓度为200mg·kg-1时明显下降.模拟酸雨加剧了高浓度Cu对白花泡桐的氧化胁迫.     

Exogenous salicylic acid improves salinity tolerance of <Emphasis Type="Italic">Nitraria tangutorum</Emphasis>

In the present study, the physiological responses of Nitraria tangutorum Bobr. seedlings to NaCl stress and the regulatory function of exogenous application of salicylic acid (SA) were investigated. NaCl in low concentration (100 mM) increased while in higher concentrations (200–400 mM) decreased the individual plant dry weights (wt) of seedlings. Decreased relative water content (RWC) and chlorophyll content were observed in the leaves of seedlings subjected to salinity stress (100–400 mM NaCl). Furthermore, NaCl stress significantly increased electrolyte leakage and malondialdehyde (MDA) content. The levels of osmotic adjustment solutes including proline, soluble sugars, and soluble protein were enhanced under NaCl treatments as compared to the control. In contrast, exogenous application of SA (0.5–1.5 mM) to the roots of seedlings showed notable amelioration effects on the inhibition of individual plant dry wt, RWC, and chlorophyll content. The increases in electrolyte leakage and MDA content in the leaves of NaCl-treated seedlings were markedly inhibited by SA application. The SA application further increased the contents of proline, soluble sugars, and soluble protein. The activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) were up-regulated by NaCl stress and the activities of SOD, POD, and CAT were further enhanced by SA treatments. Application of SA in low concentration (0.5 mM) enhanced while in higher concentrations (1.0 and 1.5 mM) inhibited APX activities in leaves of NaCl-treated seedlings. These results indicate that SA effectively alleviated the adverse effects of NaCl stress on N. tangutorum.