Hydrogen Sulfide Delays Programmed Cell Death In Wheat Aleurone Layers By Modulation Of Glutathione And Heme Oxygenase

Hydrogen sulfide (H2S) has been proposed as the third gasotransmitter, after nitric oxide (NO) and carbon monoxide (CO), H2S has been implicated in several physiological processes in animal cells. H2S is endogenously synthesized by enzymes with L-cysteine desulfydrase activity in the conversion of L-cysteine to H2S, pyruvate and ammonia. It has been reported that programmed cell death (PCD) in wheat aleurone is stimulated by Gibberellin acid (GA) and prevented by abscisic acid (ABA). We found that H2S content and L-cysteine desulfydrase activity exhibited lower levels in aleurone layers after GA treatment, whereas the opposite effect was occured in ABA treatment. To investigate relationship between H2S release and PCD, we applied a donor of H2S(NaHS) in next experiment. We also check PCD and H2S content in aleurone layers. We found that NaHS was not only to delay GA-induced PCD in a dose-dependent manner, but also to H2S content. Interestingly, application of thiotaurine (a special H2S scavenger, HT) partially blocks above processes. To eliminate the effect of sulfur-containing and sodium-containing components chemicals derived from NaHS and check the specificity of NaHS, We applied sulfur-containing and sodium-containing components chemicals in next experiment. It was also shown that H2S or HS rather than other sulfur-containing components and sodium-containing components chemicals derived from NaHS, delayed GA-induced PCD.Crucial roles in sulphur metabolism and plant defense metabolism have been described in recent years for the tripeptide thiol glutathione. We further found decreased and increased total glutathione content and the ratio of GSSH/GSSG in GA and ABA treated aleurones. NaHS also can increase total glutathione content and the ratio of GSSH/GSSG in aluerone layers. To investigate the effects of glutathione in PCD which regulated by H2S, The selective inhibitor of GSH biosynthesis buthionine-sulfoximine (BSO) and exogenous GSSH were applied to the experimental system. We observed decreased percent of live cells and total glutathione content in GA combined NaHS in the presence of BSO. Exogenous GSSH increased percent of live cells and total glutathione content. Above results illustrate H2S delays PCD in wheat aleurone layers by modulation of the glutathione.In animals, HO has recently acts as a signaling molecule involved in anti-oxidation and anti-apoptosis, and newly proved to be delay GA-induced PCD in aluerone layers. We further found decreased and increased HO-1gene expression and protein content in GA and ABA treated aleurones. NaHS also up-regulated HO-1protein and gene expression. To investigate the effects of glutathione in PCD which regulated by H2S, HO-1specific inhibitor ZnPPIX and the side-production of heme degradation catalyzed by heme oxygenase BR and CO were added in next experiment. The effect of NaHS was reversed by pretreatment with ZnPPIX; By contract, the inhibition was restored when BR and CO were added to former mentioned system. Above results illustrate H2S delays PCD in wheat aleurone layers by modulation of HO.As a conclusion, H2S content and L-cysteine desulfydrase activity exhibited lower levels in aleurone layers after GA treatment, whereas the opposite effect was occurred in NaHS treatment. NaHS can alleviate GA-induced aleurone PCD by up-regulation of H2S contents. H2S can also alleviate GA-induced aleurone PCD by up-regulation of H2S contents by up-regulation of glutathione content and HO-1expression. H2S delays PCD in wheat aleurone layers by modulation of the glutathione and heme oxygenase.