植物病原黄单胞菌毒性相关基因对内源过氧化氢的上游调控作用研究

Upstream regulation of virulent genes on endogenous hydrogen peroxide in phytopathogenic Xanthomonas

以植物病原细菌黄单胞菌的avrXa7基因和ahpC基因的2个突变体及其野生型菌株为研究对象,探讨植物病原细菌内源过氧化氢水平与菌株毒性的联系。AR/HRP法分析病原菌的过氧化氢清除力,组织化学法对细胞内过氧化氢进行定量和定位分析。结果表明,avrXa7基因的突变诱导病原菌毒性的显著降低,并引起病原菌内源过氧化氢积累水平显著下降;ahpC基因的突变诱导病原菌内源过氧化氢水平显著降低,但未能引起病原菌毒性产生显著的变化。研究结果说明,在植物病原细菌黄单胞病菌的致病机制中,病原菌内源过氧化氢的积累水平并不能直接决定菌株的毒性,而是处在avrXa7基因的下游,受到avrXa7或者更多毒性相关基因的调控,参与病原菌的致病过程。

Two mutants,avrXa7 and ahpC and their wild strains of Xanthomonas were used in the study to determine the corrleation between the endogenous hydrogen peroxide（H2O2） and the virulence of phytopathogenic Xanthomonas.H2O2 scavenging of the pathogen was determined by AR/HRP assay.The quantity and localization of endogenous H2O2 were obtained by histochemical method.The results showed that the loss of function of avirulence gene avrXa7 led to significant decrease in virulence of the patogen and resulted in a great reduction of endogenous H2O2 accumulation in avrXa7 mutant cell,while the impairment of endogenous H2O2 level caused by ahpC mutation failed to decrease the virulence of the pathogen on rice.This inferred that the H2O2 production was down-regulated by avrXa7 or other genes.H2O2 might be a downstream factor of virulent gene production acting in the pathogenetic process of pathogens.