青枯菌Po82菌株Ⅵ型分泌系统基因簇功能研究

Ⅵ型分泌系统(typeⅥsecretion system,T6SS)是革兰氏阴性细菌中新近发现的分泌系统,控制细菌的毒性和蛋白泌出。本试验构建了植物青枯菌Po82菌株的T6SS基因簇完全缺失菌株,从全局水平初步分析了T6SS的功能。与野生型菌株相比,T6SS基因簇的缺失导致了突变菌株运动能力显著增强,在接种前期突变株病情指数明显下降;通过qRT-PCR分析Ⅲ型分泌系统效应子基因,其中popA、popB和popP基因表达量上调,而popC表达水平下调。T6SS基因簇的缺失影响了Po82菌株的运动能力和Ⅲ型效应子基因的表达,使得Po82病程延长。这些结果说明,T6SS参与青枯菌的致病过程,且T6SS与T3SS之间有复杂的未知调控关系。

Functional analysis of a T6SS cluster of Ralstonia solanacearum Po82

The type Ⅵ secretion system (T6SS)is a machinery recently discovered in Gram-negative bacteria for translocation of proteins and also required for full virulence.In this study,T6SS gene cluster-deleted mutants of Ralstonia solanacearum strain Po82 were constructed in order to evaluate global functions of the T6SS cluster.We showed that the mutant strains had significantly attenuated their virulence on tomato plants in early stage.The ex-pression of type Ⅲ effector genes,popA,popB and popP,but not popC,was up-regulated revealed by real-time PCR.In addition,the motility of the mutants was increased.These results indicated that the T6SS gene cluster is involved in pathogenesis of R.solanacearum and there are complex unknown regulatory mechanisms between T6SS and T3SS.