在真核生物细胞中,各细胞器间物质和信息的交流是细胞生命活动的基本保证,而囊泡转运是细胞器之间物质和信息交流的主要方式。大多数的囊泡融合过程是由可溶性的N-乙基马来酰亚胺敏感因子连接物复合体(Soluble N-ethyl-maleimide-sensitive fusion protein attachment protein receptors,SNAREs)介导的,物种间的SNAREs具有高度保守的特性。与其他真核生物相比,植物的基因组编码更多的SNAREs。研究证明,植物的SNAREs是一个多功能的蛋白家族,在植物的许多生理过程中都有着重要的作用。本文对植物SNAREs作用的分子机理及生物学功能的最新研究进展做一概述。
In plants, the chloroplast is the main reactive oxygen species (ROS) producing site under high light stress. Catalase (CAT), which decomposes hydrogen peroxide (H2O2), is one of the controlling enzymes that maintains leaf redox homeostasis. The catalase mutants with reduced leaf catalase activity from different plant species exhibit an H2O2-induced leaf cell death phenotype. This phenotype was differently affected by light intensity or photoperiod, which may be caused by plant species, leaf redox status or growth conditions. In the rice CAT mutant nitric oxide excess 1 (noe1), higher H2O2 levels induced the generation of nitric oxide (NO) and higher S-nitrosothiol (SNO) levels, suggesting that NO acts as an important endogenous mediator in H2O2-induced leaf cell death. As a free radical, NO could also react with other intracellular and extracellular targets and form a series of related molecules, collectively called reactive nitrogen species (RNS). Recent studies have revealed that both RNS and ROS are important partners in plant leaf cell death. Here, we summarize the recent progress on H2O2-induced leaf cell death and the crosstalk of RNS and ROS signals in the plant hypersensitive response (HR), leaf senescence, and other forms of leaf cell death triggered by diverse environmental conditions.
