外源亚精胺对盐胁迫下黄瓜幼苗游离态多胺含量和多胺合成酶基因表达的影响

以黄瓜品种‘津春2号’（Cucumis sativusL.cv.Jinchun No.2）为材料,采用营养液栽培,研究了外源亚精胺（Spd）对NaCl胁迫下黄瓜幼苗叶片游离态多胺含量和多胺合成酶基因表达的影响。结果表明,75 mmol/LNaCl胁迫下,幼苗株高、茎粗和干鲜重显著降低,外源喷施1 mmol/L Spd处理可明显缓解盐胁迫对幼苗生长的抑制。盐胁迫下叶片游离态多胺含量显著增加,外源Spd进一步促进了游离态Spd和精胺（Spm）的积累,降低了游离态腐胺（Put）的积累。多胺合成酶基因表达分析表明,盐胁迫上调了adc、odc、samdc和spds基因的表达,施用外源Spd后进一步上调了samdc基因,下调了adc、odc、spds基因的表达。表明外源Spd参与了黄瓜幼苗体内多胺代谢的调节,通过下调盐胁迫下adc、odc基因的表达,抑制游离态Put的积累,上调samdc基因的表达促进游离态Spd和Spm的积累,进而缓解盐胁迫对植物生长的抑制。     

外源亚精胺对盐胁迫下白刺幼苗叶片抗氧化酶系统的影响

为进一步阐明盐生植物白刺耐盐性与多胺的关系,通过水培试验研究了叶面喷施亚精胺(Spd)对不同浓度NaCl胁迫下西伯利亚白刺幼苗叶片丙二醛(MDA)和超氧阴离子(O2)产生速率,以及抗氧化物酶系统和根系活力的影响.结果表明:叶面喷施0.1 mmol·L1 Spd 5 d后,可显著提高100和200 mmol·L1 NaCl胁迫下白刺幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性以及根系活力,降低了叶片MDA含量和O2的产生速率;而在0、50、300 mmol·L-1 NaC1处理下,外施Spd对白刺幼苗叶片上述指标无显著影响.研究结果证实,在100～200 mmol·L-1 NaCl胁迫范围内,外施亚精胺可能通过增强体内保护酶活性来显著降低活性氧水平,有效减轻盐胁迫对盐生植物白刺幼苗造成的过氧化伤害,从而增强白刺对盐环境的适应性.     

外源水杨酸对高温胁迫下葡萄几种抗氧化酶活性和抗氧化物含量的影响

本文以二年生‘克瑞森’无核葡萄为材料,探明外源水杨酸（SA）对高温胁迫下葡萄体内几种酶活性和抗氧化物质含量的影响及其在抗高温胁迫中的作用。实验结果表明,与对照相比,外源SA可以促进高温胁迫下葡萄叶片内ASA和GSH含量的积累,维持较高的APX、GR、SOD、POD和CAT活性。外源SA可能通过提高高温胁迫下葡萄体内抗氧化水平,削弱了高温胁迫对葡萄植株的氧化胁迫伤害作用。     

外源茉莉酸甲酯对盐胁迫下小桐子幼苗渗透调节和脯氨酸代谢的影响

以小桐子幼苗为材料,采用人工气候箱内水培试验,设置不同浓度(0、20、40、60、80、100μmol·L^(-1))茉莉酸甲酯(MeJA)和150 mmol·L^(-1)NaCl胁迫处理,分析不同处理条件下小桐子幼苗叶片的组织活力、MDA含量、水势、含水量和叶片渗透调节物质脯氨酸、甜菜碱和可溶性糖的含量,以及脯氨酸代谢关键酶P5CS、OAT和甜菜碱合成关键酶BADH活性和相关基因表达水平,探讨外源茉莉酸甲酯对盐胁迫下小桐子幼苗渗透调节能力的影响及其机制。结果表明:(1)外源MeJA处理可提高盐胁迫下小桐子幼苗叶片的组织活力和叶片含水量,降低小桐子幼苗叶片的MDA含量和水势,且60μmol·L^(-1)浓度处理效果最佳。(2)外源MeJA处理可提高盐胁迫下小桐子幼苗叶片的脯氨酸、甜菜碱和可溶性糖的含量,且60μmol·L^(-1)MeJA处理显著提高了盐胁迫下小桐子幼苗内源茉莉酸、脯氨酸和甜菜碱的含量。(3)60μmol·L^(-1)MeJA也提高了盐胁迫下小桐子BADH、P5CS和OAT的活性,并上调了JcBADH、JcP5CS、JcOAT基因的表达水平,但MeJA降低了脯氨酸降解酶ProDH的活性,下调了JcProDH基因的表达。研究发现,在盐胁迫条件下,外源MeJA通过活化脯氨酸生物合成的谷氨酸和鸟氨酸途径,尤其是鸟氨酸途径,以及抑制脯氨酸降解途径来促进小桐子幼苗脯氨酸的积累,同时MeJA也激活了幼苗体内甜菜碱的生物合成过程,从而强化了盐胁迫下幼苗的渗透调节作用和耐盐性,表明MeJA诱导的渗透调节在小桐子耐盐性形成过程中发挥着重要作用。     

外源亚精胺对Ca(NO3)2胁迫下番茄幼苗合特性和抗氧化酶活性的影响

以耐盐性较弱的番茄品种上海‘合作903’幼苗为试验材料,采用营养液栽培方法,研究了叶面喷施1 mmol·L-1亚精胺( Spd)对75 mmol·L-1 Ca(NO3)2胁迫下番茄幼苗生长、叶绿素含量、光合及荧光参数、叶片抗氧化酶活性的影响,以探讨外源亚精胺缓解Ca( NO3)2胁迫伤害的机制.结果显示:Ca(NO3)2胁迫能够显著抑制番茄幼苗的生长;与Ca( NO3)2胁迫处理相比,叶面喷施外源Spd 9 d后,受胁迫番茄幼苗的株高、茎粗、干重、鲜重分别显著增加70.9％、15.8％、43.4％、41.4％;叶绿素a、b的含量分别提高17.7％、13.8％;净光合速率(Pn)、气孔导度(Gx)、蒸腾速率(T1)、光合电子传递效率(rETR)和光化学猝灭系数(qp)分别升高6.6％、18.0％、31.0％、4.9％、5.0％,而胞间二氧化碳浓度(C1)、非光化学猝灭系数(q、)分别降低21.5％、8.1％;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性分别增加10.7％和37.5％,而丙二醛(MDA)含量和超氧阴离子(O2)产生速率分别显著下降34.5％、17.1％.研究表明,外源Spd通过提高番茄幼苗抗氧化酶活性来有效清除体内活性氧,维持光合机构的稳定性,提高其光合速率,从而缓解Ca( NO3)2胁迫对番茄幼苗的伤害.     

盐胁迫对红麻幼苗生长及抗氧化酶活性的影响

为研究不同盐胁迫时间和不同盐浓度胁迫对红麻（Hibiscus cannabinusL.）幼苗的生长及抗氧化酶活性的影响,探寻红麻耐盐的生理机制,为盐碱地种植红麻提供科学依据,本研究对红麻幼苗进行了两种不同条件的盐胁迫处理。一种将红麻幼苗在0（对照组）、140 mmol/L NaCl的半强度Hoagland营养液下分别处理3、6、9 d,另一种是在0（对照组）、70、140、200 mmol/L NaCl的1/2 Hoagland营养液下处理6 d,分别测定两种盐胁迫条件下植株的鲜重、根长、茎长、叶片H2O2、丙二醛（MDA）含量、超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和谷胱甘肽还原酶（GR）活性。结果显示：（1）在第一种处理条件下,随着盐胁迫时间的延长,处理组红麻幼苗的鲜重相对于对照分别减轻了19.63%、19.35%和39.03%,株高则分别降低了25.59%、19.17%和18.48%,处理组的SOD活性先增后减,POD活性先减后增,MDA和H2O2的含量、CAT和GR活性基本随胁迫时间的增长而增高。（2）在第二种处理条件下,随着胁迫盐浓度的增加,处理组鲜重相对于对照分别减轻了16.79%、19.35%和44.73%,株高则分别降低了11.21%、19.17%和23.62%,处理组SOD活性都稍高于对照,但三者无显著差异,POD活性先减后增,MDA和H2O2的含量、CAT和GR活性基本上随着盐浓度增加而增加。实验表明,在两种不同条件的盐胁迫下,红麻幼苗受盐害的程度基本上随胁迫时间和盐浓度的增加而加重。处理组植株的SOD和POD活性较对照组增加不明显,甚至有所降低,而CAT和GR活性则相对较高,CAT和GR可能在红麻幼苗抵御盐害时起较重要作用。     

外源亚精胺对盐胁迫下燕麦幼苗生长及生理特性的影响

为探讨外源喷施亚精胺(Spd)对燕麦幼苗生长和耐盐性的影响,该研究选用燕麦品种'白燕5号'为试验材料,通过水培试验研究70 mmol/L盐胁迫下(NaCl和Na2SO4摩尔比1∶1混合),叶面喷施不同浓度的亚精胺对燕麦幼苗生长、根系活力、抗氧化酶活性以及丙二醛、游离脯氨酸和离子含量的影响.结果 显示:(1)盐胁迫显著抑...     

外源Spd对低温胁迫下甜瓜幼苗光合与抗氧化特性及其相关基因表达的影响

为探讨外源亚精胺(Spd)诱导甜瓜耐低温胁迫的生理与分子机制,该研究以甜瓜耐低温品种‘世纪蜜’和低温敏感品种‘GL-1’为试验材料,在人工气候箱内采用基质栽培法,对其叶面喷施外源Spd,对低温胁迫及恢复后甜瓜幼苗生长、光合作用、抗氧化酶活性等生理指标进行测定,并利用定量PCR技术分析4种抗氧化酶基因在低温胁迫条件下的表达特性,分析外源Spd缓解低温胁迫的效应。结果表明:(1)低温胁迫显著抑制甜瓜幼苗的生长及其光合作用,降低幼苗叶绿素含量,显著增强抗氧化酶活性及相关基因表达水平,且对品种‘GL-1’影响大于‘世纪蜜’。(2)外源Spd处理可以有效促进甜瓜幼苗的生长,提高叶片叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、气孔限制值(Ls)、水分利用效率(WUE),以及最大光化学效率(Fv/Fm)、光系统Ⅱ光能捕获效率(Fv′/Fm′)和表观光合电子传递速率(ETR),降低胞间CO2浓度(Ci)和初始荧光(Fo)。(3)外源Spd可诱导低温胁迫下甜瓜抗氧化酶活性和基因表达量发生改变,并提高了低温胁迫下甜瓜幼苗叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化酶(APX)基因的表达,从而增强这些抗氧化酶活性,有效缓解低温胁迫造成的氧化胁迫伤害。(4)与对照相比,外源Spd对低温胁迫下品种‘GL-1’各指标降低或升高的幅度大于品种‘世纪蜜’。研究发现,Spd有利于甜瓜幼苗在低温胁迫下光合作用的维持,提高光合电子传递效率、光能的捕获与转换,并提高抗氧化酶活性和相关基因表达水平,促进甜瓜幼苗的生长,有效缓解低温胁迫对甜瓜幼苗生长的抑制作用,且Spd对低温敏感品种‘GL-1’缓解效果优于耐低温品种‘世纪蜜’。     

外源SNP对盐胁迫下甜瓜幼苗生长及抗氧化酶活性的影响北大核心CSCD

为明确外源一氧化氮(NO)对甜瓜幼苗耐盐性的影响,该研究以甜瓜品种‘农大甜10号’为试验材料,在300 mmol·L^(-1)NaCl胁迫条件下,叶面喷施不同浓度(50、100、150、200、250μmol·L^(-1))外源NO供体硝普钠(SNP),分析甜瓜幼苗生长、光合色素含量、细胞膜透性、抗氧化酶活性、渗透调节物质含量的变化。结果表明:(1)盐胁迫显著抑制甜瓜幼苗的生长,同时显著降低叶片光合色素含量、细胞膜透性、抗氧化酶活性、渗透调节物质含量。(2)叶面喷施150μmol·L^(-1)SNP能够显著提高盐胁迫下甜瓜幼苗的株高、茎粗、干鲜重、壮苗指数,并显著提高盐胁迫下甜瓜幼苗的光合色素含量,从而提高甜瓜的光合作用。(3)喷施150μmol·L^(-1)SNP可显著提高盐胁迫下甜瓜幼苗超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、单脱氢抗坏血酸还原酶(MDHAR)及脱氢抗坏血酸还原酶(DHAR)的活性,显著降低盐胁迫下甜瓜幼苗的丙二醛(MDA)、过氧化氢(H_(2)O_(2))含量及超氧阴离子(O^(-)·_(2))产生速率。(4)喷施150μmol·L^(-1)SNP可显著提高盐胁迫下甜瓜幼苗叶片脯氨酸(Pro)和可溶性蛋白的含量。研究认为,在盐胁迫环境下,适宜浓度的外源SNP(150μmol·L^(-1))可通过提高甜瓜幼苗的抗氧化酶活性以及光合色素和小分子可溶性有机化合物含量来增强活性氧的清除能力,降低膜脂过氧化作用,有效减轻盐胁迫对幼苗的伤害,从而增强其耐盐性,促进幼苗生长。     

Effects of ALA on Photosynthesis,Antioxidant Enzyme Activity,and Gene Expression,and Regulation of Proline Accumulation in Tomato Seedlings Under NaCl Stress

This study examined the effects of 5-aminolevulinic acid (ALA) application on photosynthesis, activity and gene expression of key antioxidant enzymes, and on proline accumulation in tomato (Lycopersicon esculentum Mill. ‘Hezuo 903’) seedlings under NaCl stress. NaCl stress significantly decreased the net photosynthetic rates and inhibited the activity of photosystem II, whereas exogenous ALA application significantly restored the net photosynthetic rates, quantum yield of electron transport, and energy conversion efficiency of photosystem II of tomato under NaCl stress. Production of superoxide, hydrogen peroxide, and malondialdehyde strongly increased in response to NaCl stress, and these increases were significantly counteracted by ALA. ALA increased the activity of reactive oxygen species (ROS) scavenging antioxidant enzymes, including superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase, and upregulated the expression of SOD, APX, and POD, genes that encode these enzymes in NaCl-treated plants. ALA simultaneously increased proline accumulation in tomato seedlings under NaCl stress by regulating the expression of genes that encode ALA biosynthetic enzymes and that control proline biosynthesis and metabolism, for example, expression of GluRS and GluTR was downregulated, accompanied by a significant increase in the expression of P5CS and decline in the expression of ProDH. ALA provided protection against NaCl stress by increasing photosynthetic capacity, regulating antioxidant enzyme gene expression and proline accumulation, and decreasing ROS accumulation and lipid peroxidation in tomato.     

Exogenous Hydrogen Peroxide Changes Antioxidant Enzyme Activity and Protects Ultrastructure in Leaves of Two Cucumber Ecotypes Under Osmotic Stress

Cucumber (Cucumis sativus L.) varieties cv. Jinchun no. 4 (a North China ecotype) and cv. Lvfeng no. 6 (a South China ecotype) were cultivated to explore the effects of osmotic stress on the ultrastructure of chloroplasts and mitochondria, as well as to assess the possible protective effect of exogenous hydrogen peroxide (H₂O₂). Under osmotic stress induced by 10% polyethylene glycol 6000, 84.3% of the chloroplasts in Jinchun no. 4 were abnormal, whereas 88.6% were abnormal in Lvfeng no. 6. Abnormal mitochondria occurred in these two strains at rates of 78.5 and 87.1%, respectively. The stress condition disintegrated the membranes of most chloroplasts and mitochondria in the leaf cells of both cucumber ecotypes, and it also increased the malondialdehyde (MDA) content. We subjected the two cultivars to a combined treatment with H₂O₂ and osmotic stress and made the following observations: (1) Abnormal chloroplasts occurred at rates of 25.7 and 28.6%, and abnormal mitochondria were observed at rates of 22.9 and 32.8%, respectively. (2) Most of the investigated membranes were well organized in leaves of Jinchun no. 4 and Lvfeng no. 6, and the levels of endogenous H₂O₂, superoxide anion, and MDA were lower. Osmotic stress and exogenous H₂O₂ both increased the activities of antioxidative enzymes such as manganese superoxide dismutase, glutathione peroxidase, catalase, guaiacol peroxidase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, dehydroascorbate reductase, and the antioxidants ascorbate and reduced glutathione. The combined effect of osmotic stress and exogenous H₂O₂ resulted in the highest antioxidant activities in both cucumber ecotypes. We propose that exogenous H₂O₂ increases antioxidant activity in cucumber leaves and thereby decreases lipid peroxidation to some extent, thus protecting the ultrastructure of most chloroplasts and mitochondria under osmotic stress.     

Potato Responds to Salt Stress by Increased Activity of Antioxidant Enzymes

To understand the response of potato to salt stress, antioxidant enzyme activities and ion content were analyzed for a sensitive and a tolerant cultivar. Nodal cuttings of the tolerant cultivar, Kennebec, and the sensitive cultivar, Concord, were exposed to media without or with 30, 60, 90 or 120 mmol/L NaCI for 4 weeks. On exposure to NaCI, the length and fresh and dry weight of both shoots and roots of Concord showed greater decrease than those of Kennebec. The decrease in shoot growth was more severe than that of the root for both cultivars. The K^＋ content of shoots and roots of both cultivars was reduced in a dose-dependent manner by exposure to NaCl; the Na^＋ content increased. Activities of ascorbate peroxidase, catalase and glutathione reductase were increased in NaCl-exposed shoots of Kennebec; the corresponding activities in NaCI-exposed shoots of Concord were decreased. Roots of both cultivars showed similar changes in the activities of these enzymes on exposure to NaCI. These studies established that enzyme activities in Concord shoots are inversely related to the NaCI concentration, whereas those in Kennebec do not show a dose dependency, which is also the case for the roots of both cultivars. Our findings suggest that an increase in activity of antioxidant enzymes, such as ascorbate peroxidase, catalase and glutathione reductase, can contribute to salt tolerance in Kennebec, a salt resistant cultivar of potato.     

Potato Responds to Salt Stress by Increased Activity of Antioxidant Enzymes

To understand the response of potato to salt stress, antioxidant enzyme activities and ion content were analyzed for a sensitive and a tolerant cultivar. Nodal cuttings of the tolerant cultivar, Kennebec, and the sensitive cultivar, Concord, were exposed to media without or with 30, 60, 90 or 120 mmol/L NaCl for 4 weeks. On exposure to NaCl, the length and fresh and dry weight of both shoots and roots of Concord showed greater decrease than those of Kennebec. The decrease in shoot growth was more severe than that of the root for both cultivars. The K+ content of shoots and roots of both cultivars was reduced in a dose-dependent manner by exposure to NaCl; the Na+ content Increased. Activities of ascorbate peroxidase, catalase and glutathione reductase were increased in NaCl-exposed shoots of Kennebec; the corresponding activities inNaCl-exposed shoots of Concord were decreased. Roots of both cultivars showed similar changes in the activities of these enzymes on exposure to NaCl. These studies established that enzyme activities In Concord shoots are inversely related to the NaCl concentration, whereas those in Kennebec do not show a dose dependency, which is also the case for the roots of both cultivars. Our findings suggest that an Increase in activity of antioxidant enzymes, such as ascorbate peroxidase,cetalase and glutathione reductase, can contribute to salt tolerance in Kennebec, a salt resistant cultivar of potato.     

植物在渗透胁迫下的基因表达及信号传递

渗透胁迫是指由于环境因素的变化使植物不能得到充足水分的一种状况。常见的渗透胁迫因素有干旱、盐害及冻害等。渗透胁迫会严重影响植物的生长发育及产量。植物在长期的进化过程中形成了一些保护机制能减轻渗透胁迫造成的伤害。比如有些植物在形态上演化生成盐腺,能排出体内的过量盐分以逃避盐害。但在渗透胁迫下几乎所有的植物都能合成一些无毒性的小分子有机物作为渗透调节剂来维持细胞内渗透势的相对稳定。在分子水平上...     

外源钙和亚精胺对NaCl胁迫条件下玉米幼苗体内离子平衡和多胺水平的调节

研究了钙离子和亚精胺对盐胁迫条件下玉米幼苗生长状况、电解质渗漏、离子含量和多胺水平的影响。结果表明盐胁迫下,钠离子和腐胺含量升高,质膜受到严重伤害,而钾离子、钙离子、亚精胺以及精胺水平降低。外加氯化钙和亚精胺不但能逆转氯化钠带来的离子平衡失调、多胺代谢紊乱,而且还能减轻氯化钠导致的生长抑制和质膜伤害。在盐胁迫条件下,二环己基胺引起多胺含量严重下降的情况在一定程度上能被外加氯化钙处理所缓解。这些结果提示,钙、多胺代谢以及盐渍环境下玉米生长之间可能存在一定的关系。     

可见分光光度法测定盐胁迫下玉米幼苗抗氧化酶活性及丙二醛含量

采用可见分光光度计法研究了盐胁迫条件下,登海9号及掖丹22两个玉米品种的幼苗中SOD、POD、CAT活性及MDA含量变化。根据这些生理指标在不同玉米品种、不同盐浓度处理下的变化规律,探求盐胁迫下玉米幼苗的抗盐生理机制。研究结果表明,随着NaCl处理浓度的提高,玉米幼苗中SOD、POD及CAT活性均有增加;当盐胁迫浓度达到60mol/L时,两玉米品种的SOD活性均达到最高,然后随NaCl处理浓度的增加,SOD活性逐渐降低;当盐胁迫浓度达到40mol/L时,两玉米品种的POD活性均达到最高,然后随NaCl处理浓度的增加,POD活性逐渐降低;当盐胁迫浓度达到40mol/L时,掖丹22的CAT活性达到最高,当盐胁迫浓度达到60mol/L时,登海9号的CAT活性达到最高,然后随NaCl处理浓度的增加,CAT活性逐渐降低。随着NaCl处理浓度的提高,玉米幼苗叶片中的MDA含量均有增加,当浓度大于40mol/L时,增加幅度加大。     

盐胁迫下盐芥渗透调节物质的积累及其渗透调节作用

用含有NaCl0、50、100、200、300、400mmol/L的Hoagland培养液处理盐芥幼苗一定时间后,分别测定其根和叶含水量、渗透势、几种无机和有机渗透调节物质含量,并计算了渗透调节物质在不同条件下的计算渗透势值(COP).结果表明:随盐处理浓度的增加,盐芥根和叶的含水量和渗透势逐渐降低;Na 和Cl-是根和叶积累的无机渗透调节物质;SS、OA和FAA是根积累的有机渗透调节物质,Pro是叶和根积累的有机渗透调节物质.Na X-ray微区分析表明液泡是积累Na 的主要部位.     

外源硼对铝胁迫小麦幼苗的缓解效应（简报）

铝胁迫下,１０－２０μmol.L^-1的外源硼能不同程度地提高麦苗的干物质积累,降低麦苗组织中丙二醛含量、多酚氧化酶活性和组织中也解质泄漏率。