ABSTRACT

We examined the effects of Cd and Zn exposure on the photosynthetic function and the tolerant mechanisms of ROS metabolism in tobacco leaves. The results showed that the photosynthesis inhibition caused by Cd exposure was due to the limitation of both stomatal and non-stomatal factors, while Zn exposure only showed a significant effect on the Gs of tobacco leaves. Cd increased the generation rate of O₂•– and the content of H₂O₂, but Zn did not lead to the ROS burst. Cd enhanced the POD activity, but inhibited SOD and CAT activities. The activities of SOD and POD significantly increased under Zn exposure. Cd inhibited the activity and expression of APX. The up regulation of GPX, GR and GST expression and the increase of their activities also play a positive role in the adaptation to Cd. Although Zn inhibited the activities of APX and GPX, it had little effect on other enzyme activities and protein expression in AsA-GSH cycle. TPX and TrxR activities, Trx-Prx pathway-related proteins are very sensitive to Cd. However, only PrxQ and 2-Cys Prx BAS1, which are located in chloroplast, and Trx-HFC164 were significantly down-regulated in Trx-Prx pathway under Zn exposure.

摘要

我们研究了 Cd 和 Zn 暴露对烟叶光合功能和 ROS 代谢耐受机制的影响。结果表明，Cd暴露引起的光合作用抑制是由于气孔和非气孔因素的限制，而Zn暴露仅对烟叶Gs有显着影响。Cd 增加了 O ₂ •–的生成率和 H ₂ O ₂的含量，但 Zn 并没有导致 ROS 爆发。Cd增强了POD活性，但抑制了SOD和CAT活性。SOD和POD的活性在Zn暴露下显着增加。Cd抑制APX的活性和表达。GPX、GR和GST表达的上调及其活性的增加也对Cd的适应起积极作用。Zn虽然抑制了APX和GPX的活性，但对AsA-GSH循环中的其他酶活性和蛋白表达影响不大。TPX 和 TrxR 活性、Trx-Prx 通路相关蛋白对 Cd 非常敏感。然而，只有位于叶绿体中的 PrxQ 和 2-Cys Prx BAS1 以及 Trx-HFC164 在 Zn 暴露下在 Trx-Prx 通路中显着下调。