Wang Meiping, Jia Yunli, Xu Ziwei, Xia Zongliang
College of Life Science, Henan Agricultural University Zhengzhou, China.
Front Plant Sci. 2016 Dec 2;7:1843. doi: 10.3389/fpls.2016.01843. eCollection 2016.
As an essential enzyme in the sulfate assimilation reductive pathway, sulfite reductase (SiR) plays important roles in diverse metabolic processes such as sulfur homeostasis and cysteine metabolism. However, whether plant is involved in oxidative stress response is largely unknown. Here, we show that functions in methyl viologen (MV)-induced oxidative stress in . The transcript levels of were higher in leaves, immature siliques, and roots and were markedly and rapidly up-regulated by MV exposure. The knock-down transgenic lines had about 60% residual transcripts and were more susceptible than wild-type when exposed to oxidative stress. The severe damage phenotypes of the -impaired lines were accompanied by increases of hydrogen peroxide (HO), malondialdehyde (MDA), and sulfite accumulations, but less amounts of glutathione (GSH). Interestingly, application of exogenous GSH effectively rescued corresponding MV hypersensitivity in -impaired plants. qRT-PCR analysis revealed that there was significantly increased expression of several sulfite metabolism-related genes in -impaired lines. Noticeably, enhanced transcripts of the three genes were quite evident in -impaired plants; suggesting that the increased sulfite in the -impaired plants could be a result of the reduced coupled to enhanced expression during oxidative stress. Together, our results indicate that is involved in oxidative stress tolerance possibly by maintaining sulfite homeostasis, regulating GSH levels, and modulating sulfite metabolism-related gene expression in . could be exploited for engineering environmental stress-tolerant plants in molecular breeding of crops.
作为硫酸盐同化还原途径中的一种关键酶，亚硫酸盐还原酶（SiR）在硫稳态和半胱氨酸代谢等多种代谢过程中发挥着重要作用。然而，植物SiR是否参与氧化应激反应在很大程度上尚不清楚。在此，我们表明SiR在拟南芥中参与甲基紫精（MV）诱导的氧化应激。SiR的转录水平在叶片、未成熟角果和根中较高，并且通过MV处理显著且迅速地上调。SiR基因敲除的转基因株系具有约60%的残留转录本，并且在暴露于氧化应激时比野生型更敏感。SiR功能受损株系的严重损伤表型伴随着过氧化氢（H₂O₂）、丙二醛（MDA）的增加和亚硫酸盐积累，但谷胱甘肽（GSH）含量较少。有趣的是，外源GSH的施用有效地挽救了SiR功能受损植物中相应的MV超敏反应。qRT-PCR分析表明，SiR功能受损株系中几个亚硫酸盐代谢相关基因的表达显著增加。值得注意的是，在SiR功能受损的植物中，三个SiR基因的转录本增强非常明显；这表明SiR功能受损植物中亚硫酸盐的增加可能是氧化应激期间SiR减少与SiR表达增强相结合的结果。总之，我们的结果表明，SiR可能通过维持亚硫酸盐稳态、调节GSH水平以及调节拟南芥中亚硫酸盐代谢相关基因的表达来参与氧化应激耐受性。在作物分子育种中，SiR可用于培育耐环境胁迫的植物。
