H_(2)S信号参与SDH调控能量和活性氧代谢过程的作用机制

SDH-induced H_(2)S Generation is Involved in Energy and ROS Metabolic Processes in Arabidopsis

作为新兴的气体信号分子,硫化氢(hydrogen sulfide,H_(2)S)能够调节植物生长发育,广泛参与植物抵御生物及非生物胁迫的过程。琥珀酸脱氢酶(succinate dehydrogenase,SDH)结合于线粒体内膜,既是参与三羧酸循环的关键酶,也是氧化磷酸化过程的重要电子载体,在植物响应各类胁迫中发挥着重要作用。鉴于H_(2)S与SDH参与调控的生理过程有很大相关性,本文以模式植物拟南芥为实验材料,对H_(2)S与SDH之间的关系进行了探索。结果表明,在AtSDH1-1-OE中,H_(2)S的关键生成酶编码基因LCD和DES 1大量表达,且H_(2)S产率和含量较WT显著升高。SDH抑制剂TTFA处理导致活性氧(ROS)大量产生,幼苗根的伸长受到极显著抑制,根发育生长基因RHD2、TRH和SCN 1表达下调,而同时进行生理浓度的NaHS(H_(2)S供体)熏蒸,能够清除过量ROS,幼苗生长有所恢复。但在AtSDH1-1-OE中,施加HT(H_(2)S清除剂)后的结果与TTFA单独处理WT类似,ROS大量产生,幼苗根长变短。H_(2)S特异性荧光探针和非损伤微测技术NMT检测结果也显示,TTFA和HT诱导保卫细胞中H_(2)O_(2)增加,H_(2)S则可以促使其排出。此外,H_(2)S影响ATP合成相关基因表达,促使ATP大量产生,相应地,在AtSDH1-1-OE中施加HT处理,ATP含量显著降低。综上所述,SDH诱导植物H_(2)S的内源产生,进而参与SDH调控植物体内能量代谢和ROS的产生过程,最终影响植株根的伸长。

Hydrogen sulfide(H_(2)S)has been recognized as a new gasotransmitter with diverse functions in plants under physiological,pathogenic and adverse environmental conditions.Succinate dehydrogenase(SDH),bound to the inner mitochondrial membrane,is the only enzyme shared by both the electron transport chain and the tricarboxylic acid cycle in mitochondria,playing an important role in plant responses to various stresses.In view of the correlation between H_(2)S and SDH involved in diverse physiological processes,their relationship between the two with Arabidopsis was exploredin this paper.The results showed that LCD and DES 1,two genes encoding H_(2)S production enzymes in Arabidopsis,were abundantly expressed in AtSDH1-1-OE,and the H_(2)S production was significantly higher compared to WT.TTFA(SDH inhibitor)induced massive ROS production and significantly inhibited seedling root elongation,as well as down-regulated the expression of root growth related genes RHD2,TRH,and SCN 1.However,physiological concentrations of NaHS(H_(2)S donor)cleared the excess ROS induced by TTFA,and seedling growth was restored to some extent.The application of HT(H_(2)S scavenger)impaired root growth in AtSDH1-1-OE,which was similar to the treatment of TTFA in WT.H_(2)S-specific fluorescence probe and NMT assays also indicated that TTFA and HT induced an increase of H_(2)O_(2) in guard cells,while H_(2)S could drive its efflux.In addition,H_(2)S affected the expression of genes related to ATP synthesis and contributed to the production of ATP.Accordingly,the ATP content was significantly reduced by applying HT in AtSDH1-1-OE.In summary,SDH could induce the production of endogenous H_(2)S in plants,which in turn is involved in the regulation of energy metabolism and ROS production in plants by SDH and eventually affects the elongation of the roots.