title: Impairment of Sulfite Reductase Decreases Oxidative Stress Tolerance inArabidopsis thaliana.
abstract: 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 plantSiRis involved in oxidative stress response is largely unknown. Here, we show thatSiRfunctions in methyl viologen (MV)-induced oxidative stress inArabidopsis. The transcript levels ofSiRwere higher in leaves, immature siliques, and roots and were markedly and rapidly up-regulated by MV exposure. TheSiRknock-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 theSiR-impaired lines were accompanied by increases of hydrogen peroxide (H2O2), malondialdehyde (MDA), and sulfite accumulations, but less amounts of glutathione (GSH). Interestingly, application of exogenous GSH effectively rescued corresponding MV hypersensitivity inSiR-impaired plants. qRT-PCR analysis revealed that there was significantly increased expression of several sulfite metabolism-related genes inSiR-impaired lines. Noticeably, enhanced transcripts of the threeAPRgenes were quite evident inSiR-impaired plants; suggesting that the increased sulfite in theSiR-impaired plants could be a result of the reducedSiRcoupled to enhancedAPRexpression during oxidative stress. Together, our results indicate thatSiRis involved in oxidative stress tolerance possibly by maintaining sulfite homeostasis, regulating GSH levels, and modulating sulfite metabolism-related gene expression inArabidopsis.SiRcould be exploited for engineering environmental stress-tolerant plants in molecular breeding of crops.
authors.affiliation: College of Life Science, Henan Agricultural University Zhengzhou, China.
authors.forename: Meiping
authors.initials: M
authors.lastname: Wang
authors.affiliation: College of Life Science, Henan Agricultural University Zhengzhou, China.
authors.forename: Yunli
authors.initials: Y
authors.lastname: Jia
authors.affiliation: College of Life Science, Henan Agricultural University Zhengzhou, China.
authors.forename: Ziwei
authors.initials: Z
authors.lastname: Xu
authors.affiliation: College of Life Science, Henan Agricultural University Zhengzhou, China.
authors.forename: Zongliang
authors.initials: Z
authors.lastname: Xia
keywords: glutathione; methyl viologen; oxidative stress; sulfite reductase