【作者】 周卫；

【导师】 张楚富；

【作者基本信息】 武汉大学 ， 生物化学与分子生物学， 2004， 硕士

【摘要】 盐渍对植物的生长发育有着严重的影响,抑制植物生长,降低农作物产量,为了了解盐胁迫对水稻氮素同化的影响,在盐（NaCl）胁迫下,我们检测了耐盐性不同的水稻品种根部氨的同化酶及相关参数。结果显示,根系总可溶性蛋白、GS及NADH-GOGAT活性在高盐浓度下呈不同程度的降低,表现出与其耐盐性相一致,提示耐盐性品种的高GS/GOGAT活性是NH₄⁺浓度维持在较低水平的主要原因。GS同工酶Native-PAGE结果显示,GSrb更容易受到盐胁迫的影响。组织中NH₄⁺含量的显著上升,诱导了NADH-GDH活性的上升,使NADH-GDH在氨同化中所起的作用加强,以减轻水稻因NH₄⁺的积累而造成的伤害,起到保护的作用。在供试的品种中,耐盐性较强的品种糖的积累更为显著,表明TSS在盐胁迫条件下,起着维持渗透压的调节作用,以减轻盐胁迫对GS和GOGAT活性的影响。在本实验中,盐胁迫下Proline的含量也均有不同程度的升高,在耐盐性较低的品种中,这种趋势更为明显。 水分胁迫对水稻氨同化酶的影响也是环境胁迫研究的重要内容之一,我们对等渗条件下的盐和水分胁迫对水稻氨同化的影响进行了比较研究。在盐（NaCl）胁迫和等渗的聚乙二醇PEG-6000（Polyethylene glycol 6000）引起的水分胁迫下,检测了水稻叶片NH₄⁺同化酶及其相关参数。通过对胁迫后水稻叶片组织中NH₄⁺的水平变化、氨同化酶及渗透调节物质的比较分析,两种胁迫均对水稻叶片NH₄⁺的同化均产生了显著的影响。等渗条件下,与水分胁迫相比,盐胁迫更显著的抑制了GS的活性,造成叶片中NH₄⁺的积累水平更高。与盐胁迫一样,NH₄⁺的积累同样引起了水分胁迫下NADH-GDH的水平的上升,但水分胁迫下NADH-GDH上升幅度没有盐胁迫下明显,这种趋势与NH₄⁺水平的变化一致,说明渗透胁迫下,NADH-GDH活性的上升主要是因NH₄⁺的积累所引起。更多还原

【Abstract】 The effects of NaCl-stress on ammonia assimilation enzymes and the related parameters were determined in the roots of three rice {Oryza sativa L.) cultivars differing in salt tolerance. The results showed that the activities of glutamine synthetase (GS) and NADH-dependent glutamate synthase (NADH-GOGAT), as well as the levels of soluble protein decreased under high concentration salt. The influence extent was in accordance with Zao-hua 2 (salt-sensitive), Jin-zhu 1 (normal cultivar), Jin-dao 779 (salt-resistant), which was consistent with their salt-tolerance. Results from native-PAGE and activity dyeing indicated that GSrb by external nitrogen is more sensitive to the change of the external condition. Under the stress of high salt concentration, NADH-dependent glutamate dehydrogenase (NADH-GDH) activity of Zao-hua 2 and Jin-zhu 1 was induced significantly, but that of Jin-dao 779 did not increased remarkably. The salt stress led to the accumulation of total soluble sugar (TSS) in the root of Jin-zhu 1 and Jin-dao 779 in different degree. The level of TSS in Zao-hua 2 changed with different NaCl concentration, this suggested that the increase of TSS level would decrease the loss of water to keep the relative balance of ions in tissue, and play a role in making the activity of GOGAT and GS enzymes higher. Among the cultivars observed, content of proline increased in different degree, but under high salt concentration, it had a more marked rise in the roots of salt-sensitive cultivars.Under salt stress and iso-osmotic water stress brought by Polyethylene glycol 6000 (PEG-6000), ammonium assimilation enzymes and the relative parameters of the leaves of rice seedlings were detected. Analyzing for ammonium concentration,ammonium-assimilating enzymes, and osmoregulatory solutes showed ammonium assimilation enzymes was affected significantly by two kinds of stress. Under the iso-osmosis condition, compared with water stress, the activity of glutamine synthetase (GS) was remarkably decreased by salt stress which caused a more significant ammonium accumulation in the leaves. The activity of NADH-dependent glutamate dehydrogenase (NADH-GDH) was induced during the ammonium concentration was enhanced under these stress conditions.更多还原