【摘要】 青枯菌Ralstonia solanacearum是全球作物生产中的一种重要病原细菌。由青枯菌引起的植物细菌性枯萎病(简称青枯病)危害数百种经济作物并造成严重经济损失。环二鸟苷酸(cyclic diguanylate, c-di-GMP)是一种广泛存在于细菌中的第二信使分子，通过调控生物膜形成、运动性等影响病原菌致病力。但在青枯菌中，c-di-GMP的调控网络并不清楚。本试验以青枯菌GMI 1000中的c-di-GMP降解酶基因gedrG缺失突变体菌株(ΔgedrG-GMI)为研究对象，将pMiniHimarI RB1质粒通过双亲共结合法导入ΔgedrG-GMI突变体，筛选运动性表型恢复的转座子插入突变体(transposon mutagenesis),共鉴定了13 272株转座子插入突变体。其中，转座子插入vsrD基因时，ΔgedrG-GMI运动性恢复为野生型水平。分析表明vsrD基因缺失后，突变株运动性极显著增强，胞内c-di-GMP水平降低，致病力丧失，vsrD基因互补菌株运动性恢复至缺失前水平。以上结果表明，vsrD参与了青枯菌GMI 1000中c-di-GMP调控通路，影响GMI 1000运动性，且与致病性密切相关。更多还原

【Abstract】 Ralstonia solanacearum is an important pathogen in crop production worldwide. The bacterial wilt caused by R.solanacearum affects hundreds of crops and causes serious economic losses. Cyclic diguanylate(c-di-GMP) is a widely distributed second messenger molecule in bacteria, which can regulate biofilm formation, motility, and other factors that affect pathogenicity. However, the regulatory network of c-di-GMP in R.solanacearum remains unclear. In this study, the c-di-GMP degrading enzyme gene gedrG deletion mutant strain ΔgedrG-GMI was used as test object. The pMiniHimar1 RB1 plasmid was introduced into the ΔgedrG-GMI mutant by biparental conjugation. Transposon mutagenesis was used to screen for mutants with recovered motility phenotypes. A total of 13 272 transposon mutants were identified. When the transposon inserted into the vsrD gene, motility in ΔgedrG-GMI was restored. Analysis showed that the deletion of vsrD resulted in significantly enhanced motility, reduced intracellular c-di-GMP levels, and loss of virulence. However, the motility of the vsrD complementation strain was restored to the pre-deletion level, but virulence was not restored. These results indicate that vsrD is involved in the regulation of the c-di-GMP pathway in R.solanacearum GMI 1000 and is closely related to its pathogenic mechanism.更多还原