【作者】 刘俊；

【导师】 刘友良；

【作者基本信息】 南京农业大学 ， 植物学， 2004， 博士

【摘要】 盐胁迫可以显著地降低作物产量，提高作物的耐盐性对农业生产意义重大。多胺是植物体内一种重要的生理活性物质，在植物逆境胁迫的适应中具有重要的作用。环境胁迫可以引起植物组织中多胺水平发生很大变化，同时多胺在逆境信号的转导中也可能发挥作用。植物体内的多胺分为游离态多胺、高氯酸（PCA）可溶和PCA不溶性结合态多胺，在盐胁迫下这三种状态的多胺及其在信号转导中的作用与抗盐性的关系还不清楚。本文选用两个抗盐能力不同的大麦品种科品7号（KP7，抗盐性较差）和鉴4（J4，抗盐性较强）作为研究材料，结合多胺合成抑制剂D-Arg、DFMO和MGBG以及外源调控物质甜菜碱和CaCl₂处理研究盐胁迫下大麦幼苗体内游离态和结合态多胺的变化及其与抗盐性之间的关系。同时以常规玉米（农大108）以及ABA缺失突变体及其野生型玉米叶片为研究材料，结合ABA合成抑制剂Tungstate、多胺氧化酶（PAO）合成抑制剂Guazatine来调查盐胁迫下多胺含量的变化与ABA和H₂O₂诱导的信号之间的关系。 结果表明用0～300mmol／L NaCl处理大麦（KP7和J4）幼苗可以促进根系中的Put向Spd和Spm转化，增加Spd和Spm的含量，提高（Spd+Spm）／Put的比值，且耐盐性品种J4体内多胺的转化对盐浓度响应的阈值要大于盐敏感品种KP7。外施多胺合成抑制剂D-Arg、DFMO和MGBG降低了盐胁迫下根系游离多胺的总量及Put向Spd和Spm的转化，也加重了盐胁迫的伤害。 外源甜菜碱对200mmol／L NaCl胁迫下大麦幼苗的伤害有显著的缓解效应，并且可以显著地提高盐胁迫下大麦幼苗根系多胺含量，促进叶片内Put向Spd与Spm的转化，提高叶片的（Spd+Spm）／Put的比值。表明外源甜菜碱对大麦幼苗在盐胁迫下对多胺代谢的调节是其缓解盐害的一个重要机制。 盐胁迫也影响了幼苗体内PCA可溶性结合态与PCA不溶性结合态多胺的含量。200mmol／L NaCl胁迫8天后，大麦幼苗叶片和根系中的PCA可溶性结合态与PCA不溶性结合态多胺的含量都有不同程度地下降。盐胁迫也降低了大麦幼苗细胞壁结合的多胺含量。Ca²⁺处理可以显著地减轻盐胁迫对大麦幼苗的伤害，并引起其根系质外体中游离多胺以及细胞壁结合多胺含量的显著上升，同时也促使了细胞壁结合型PAO和POD活性的下降，增加了根系可溶性蛋白中结合的多胺含量，因此细胞壁结合多胺含量的增加以及根系可溶性蛋白中结合多胺含量的上升是ca”处理缓解大麦盐害的一个可能原因。 外源施用Inllllol/L的Cad、Put、SPd和SPm处理，可以显著地增加盐胁迫下大麦幼苗根系以及玉米叶片中活性氧代谢的酶以T、SOD和POD的活性.多胺处理也促进了盐胁迫下大麦幼苗根系质膜和液泡膜上的H+一ATPase的活性，且对离子吸收和分配产生了显著影响，并显著地增加了盐胁迫下玉米叶片的光合性能。 盐处理24h后，玉米幼苗叶片中多胺含量显著地增加，ABA生物合成抑制剂Tullgs tate，以及ABA缺失突变体与其野生型玉米（于尹到VPS）可以抑制其体内ABA的生成，并显著地降低盐胁迫下多胺含量的增高。多胺合成抑制剂D一Arg和DFMO也可以降低ABA诱导的多胺含量增高。表明盐胁迫促使ABA含量增加，而ABA的增加又诱导了多胺的合成。 ABA合成抑制剂TullgS tate和PAO抑制剂guazatine可以极大地降低盐胁迫和ABA处理引起的PAO活性的升高，降低H20，的水平，也抑制了多胺含量的增加。低浓度（1阳o1/L）H20，可以诱导玉米叶片中多胺含量的增加，但高浓度的HZOZ显著降低了叶片中多胺的水平。表明多胺在盐胁迫下的合成是可以通过ABA和H202来介导的，并在其下游发挥对盐害的缓解作用。更多还原

【Abstract】 Salt stress affects every aspect of physiology in crops, as a result virtually reduces their productivity. One of strategies for agriculture is to improve the salt tolerance of crops. As adaptive response, plants can effectively adjust their physiology and metabolism to reduce stress injury. Polyamines, mainly Put, Spd and Spm, response not only to adverse conditions but signal transduction in higher plants. However, the mechanism is still not well established in the relationships between polyamine forms (free, PCA soluble and PCA insoluble) and salt tolerance, moreover, whether polyamine participate the stress signaling remains unclear. Therefore, two barley cultivars (Hordewn vulgare L.) differing in salt tolerance (J4, salt-tolerance; KP7, salt-sensitive), and polyamine biosynthesis inhibitors D-Arg, DFMO, MGBG and CHA, which inhibits arginine decarboxylase (ADC), ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC) and spermidine synthase respectively, polyamines, glycine betaine (GB) and CaCl2 were utilized to study the relationships between polyamine metabolism and salt tolerance. Meanwhile, maize (Zea mays L cv nongda 108, VP line MIA4, VP5/VP5), ABA biosynthesis inhibitor Tungstate and PAO inhibitor Guazatine were also employed to investigate the roles of polyamines in stress signaling.The result indicated that the conversion of Put to Spd and Spm was provoked in barley roots by NaCl (0-300 mmol/L) treatment. Due to the increase of Spd and Spm contents, the ratio of (Spd+Spm)/Put was obviously enhanced. D-Arg, DFMO and MGBG treatments not only reduced the polyamine levels and the conversion of Put to Spd and Spm, but further injured the salt stressed seedlings. However the injury was obviously ameliorated by exogenous GB. GB (1 mmol/L) treatment increased the polyamine levels and the conversion ofPut to Spd and Spm in the barley roots under salt stress, thus, it also enhanced the ratio of (Spd+Spm)/Put. These results indicated that the higher ratio of (Spd+Spm)/Put was advantageous to plant salt tolerance.Salt stress caused the decrease of PCA soluble and insoluble conjugated polyamines levels in barley roots. As one part of conjugated polyamines, cell wall residue (CWR) conjugated polyamines in the roots also decreased under salt stress, and exogenous calcium treatment could effectively reverse this effect. Calcium treatment also reduced the injury caused by salt stress, and resulted in the increase of free polyamines in apoplast as well as conjugated polyamines in soluble proteins in roots of barley seedlings as compared with thecontrol of salt stress.Exogenous polyamines ameliorated the salt stress injury and caused the increase in activities of SOD, CAT and POD in barley roots under salt stress. Such treatments also caused the decrease of the rate of 0~2 production, but resulted in the accumulation of AsA compared with the control of salt treatment. Plasma membrane and tonoplast H+-ATPase, which regulates the ion and pH balance, were significantly activated by polyamine treatments, as the result, the ration of K+/Na+ increased and the ion homeostasis were reestablished in barley roots. Exogenous polyamine treatments also increased the conjugated polyamine levels in chloroplast of maize seedlings under salt stress. As compared with salt stress, the PS1I primarily chemical efficiency (Fv/Fm) and net photosynthetic rate also enhanced under polyamine treatment. These results showed that exogenous polyamines had a protective effect on plants subjected to salt stress.In leaves of maize seedlings, polyamine content increased significantly after 24h of exogenous ABA and salt stress treatments. Salt stress also led to an increase in the endogenous ABA level. We used ABA deficient mutant (VP5/FP5) and ABA biosynthesis inhibitor tungstate to reduce ABA production, which resulted in the reduction in polyamine content compared with the control of salt stress. The polyamine synthesis inhibitors D-Arg and DFMO also reduced the polyamine content in leaves of maize seedling under salt st更多还原