Study On The Mechanism For Glutathione Regulating Hydrogen Peroxide Signaling In Arabidopsis Thaliana

Recently,accumulated studies have suggested that reactive oxygen species are important signaling molecules that participate in various biological processes between plants and environment stress.The hydrogen peroxide(H₂O₂)produced by photorespiration in Arabidopsis induces the accumulation of glutathione and nitric oxide and plays a key role in the defense response by modulating the salicylic acid pathway.However,the important factors that link glutathione and nitric oxide in plant cells to regulate the H2O2-induced salicylic acid signaling pathway remain elusive.Therefore,in this study,Arabidopsis cat2 mutant was used as an important genetic material to study the influence of GSNOR1 on H₂O₂-dependent signaling pathway.It was shown that the introduction of the gsnor1-3 mutation into the cat2 background increased SNO levels and eliminated cat2-triggered cell death and salicylic acid accumulation,but did not alter the oxidative stress state.Further analysis of the cat2 cad2 and cat2 pad2mutants revealed that the lack of glutathione can cause high levels of SNO and inhibit the activity of GNSOR1.Using biotin switch technology to analyze nitrosylation in vivo and in vitro,it was found that in the presence of GSH,the nitrosolation of GSNOR1decreased and the activity of the enzyme increased,suggesting that GSNOR1 was post-translationally regulated by denitrification in a glutathione-dependent manner.In addition,TRXh5,as an important selective denitrosylase,plays a key role in the SA-dependent immune response.However,the interaction between GSH and TRXh5 to regulate H₂O₂ signaling has been rarely reported.By analyzing the physiological states of the mutant and transgenic plants,it was found that the double mutations of trxh5 and pad2 inhibited SA accumulation and PR gene expression,and the overexpression of TRXh5 promoted oxidative stress in cat2,while there was no change in cat2 pad2.The results suggest that the function of TRXh5 is dependent on glutathione to promote oxidative signaling.Further study on the interaction between GSH and TRXh5,it is found that GSH can reduce the nitrosylation state of TRXh5,which in turn affects the signal transmission of H₂O₂.Therefore,I conclude that glutathione mediated denitrosoylation of GSNOR1 and TRXh5 is a key factor in activating H₂O₂-induced salicylic acid signaling,and that glutathione is essential for maintaining the biological function of GSNOR1 or TRXh5.