【摘要】 通过研究大豆胚轴生长及内源吲哚乙酸 IAA 、赤霉素 GAs 、过氧化物酶 POD 和吲哚乙酸氧化酶 IAAoxidase 活性变化对Cd、UV-B辐射和Cd+UV-B 复合胁迫 的响应.分析了激素水平、酶活性变化以及胚轴生长变化特性.结果表明,UV-B辐射引起大豆上胚轴伸长减小;但Cd对上胚轴伸长无明显影响;Cd+UV-B使上胚轴长度比UV-B作用时明显增加.UV-B辐射显著降低了胚轴IAA含量;而GAs含量却显著升高;Cd胁迫下IAA和GAs变化并不明显;但Cd+UV-B使IAA含量显著升高,而对GAs无明显影响.UV-B辐射使IAA氧化酶和POD活性显著增强,而Cd对这两种酶活性影响并不明显;但Cd+UV-B复合胁迫下胚轴的IAA水平较高.尽管UV-B辐射引起胚轴中GAs含量显著增加,但研究结果显示IAA含量变化是胁迫下引起胚轴生长改变的更直接原因.研究还表明Cd+UV-B时,大大削弱了UV-B辐射下IAA氧化酶活性增强,加之Cd对POD活性的抑制,导致复合胁迫下胚轴的IAA水平较高,证明复合胁迫可以改变单一胁迫下植物激素的调控机制.更多还原

【Abstract】 It was investigated that the changes in levels of indole acetic acid (IAA) and gibberellins (GAs) in soybean epicotyl exposed to Cd,enhanced UV-B radiation and combination of Cd and UV-B radiation (Cd+UV-B).The levels of IAA and GAs and characteristics of epicotyl elongation under stresses have been analyzed.The results show that UV-B radiation could decrease elongation of epicotyl and increase its diameters;Cd stress has no obvious effect on epicotyl length.Obvious increase in epicotyl length and decrease in their diameters exposure to Cd+UV-B has been discovered.UV-B radiation caused significant decrease in IAA content and increase in GAs contents (P<0.05);Under Cd stress the changes in IAA and GAs levels was not obvious.UV-B radiation enhanced significantly activities of IAA oxidase and peroxidase (POD).Cd could suppress the UV-induced up-regulation of the IAA oxidase activity and keep higher level of IAA in epicotyl under Cd+UV-B,which may be the decisive causes of increase in elongation and decrease in diameter of epicotyl.Although UV-B radiation could lead to marked increase in GAs level,the changes in IAA level may be primary and direct reason of inducing changes in epicotyl growth.It also suggested that Cd+UV-B stress could change the hormones regulation abilities under stress of single factor.更多还原