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以DR5-GUS转基因水稻(以水稻中花11为背景)为试验材料,分析镉胁迫下超氧阴离子(O_2~-·)介导的根系生长动态变化与生长素重新分布之间的关系。结果发现,在镉胁迫与非胁迫条件下DDC(SOD抑制剂)处理明显促进了根系的生长。GUS活性检测显示DDC和Cd+DDC处理条件下根系生长的动态变化与生长素浓度和分布的动态变化密切相关。进一步研究显示,DDC+BFA(蛋白运输抑制剂)/MG132/(蛋白降解抑制剂)或Cd+DDC+BFA/MG132处理比DDC或Cd+DDC处理增强了GUS活性。这些结果证实O_2~-·介导的生长素重新分布与蛋白转运/降解有密切关系,O_2~-·与生长素信号之间存在交互作用。以上结果表明,适量的O_2~-·通过蛋白转运/降解介导的生长素重新分布是镉胁迫及非胁迫条件下水稻幼苗根系生长特别是不定根和侧根生长所必需的。
The relationship between dynamic changes of root growth and auxin redistribution induced by superoxide anion (O_2 - · ·) under cadmium stress was investigated using DR5-GUS transgenic rice (Zhonghua 11 as background). The results showed that under Cd stress and non-stress conditions DDC (SOD inhibitor) treatment significantly promoted root growth. The GUS activity assay showed that the dynamic changes of root growth under the conditions of DDC and Cd + DDC were closely related to the dynamic changes of the concentration and distribution of auxin. Further studies showed that GUS activity was enhanced by either DDC + BFA (protein transport inhibitor) / MG132 / (protein degradation inhibitor) or Cd + DDC + BFA / MG132 treatment than DDC or Cd + DDC treatment. These results confirm that O 2 ~ - · mediated redistribution of auxin is closely related to protein transport / degradation, and there is an interaction between O 2 ~ - · and auxin signaling. The above results showed that proper amount of O_2 - auxin redistribution mediated by protein transport / degradation was necessary for root growth, especially adventitious root and lateral root growth of rice seedlings under cadmium stress and non-stress conditions.