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【目的】旨在阐明双组分系统RpfCxoc/RpfGxoc在水稻细菌性条斑病菌(Xanthomonas oryzae pv.oryzicola,Xoc)DSF(diffusible signal factor)合成、致病性等相关方面的生物学功能。【方法】以Xoc野生型菌株Rs105为母体,利用自杀载体pK18mobsacB缺失突变rpfCxoc、rpfGxoc和rpfGCxoc(rpfCxoc和rpfGxoc双基因),测定突变体及其互补菌株的DSF合成水平、对水稻的致病性、胞外多糖(extracellular polysaccharide,EPS)产量、菌体形态及群体结构。【结果】从Rs105基因组中克隆了rpfCxoc和rpfGxoc基因,并获得了相应的单基因或双基因缺失突变体。与Rs105相比,ΔrpfCxoc和ΔrpfGCxoc过量合成DSF信号分子,但是ΔrpfGxoc合成DSF的能力显著下降;rpfCxoc和rpfGxoc单基因或双基因的缺失突变均导致Xoc的致病性丧失,EPS合成水平下降34.1%-48.5%,形成菌体高度聚集的生物膜结构。【结论】RpfCxoc/RpfGxoc双组分系统调控Xoc的DSF生物合成、EPS产生和生物膜的驱散,是Xoc保持致病性所必需的因子。
【Objective】 The aim of this study was to elucidate the biological functions of the two-component system RpfCxoc / RpfGxoc in the synthesis of pathogenicity of Xanthomonas oryzae pv.oryzicola (Xoc) DSF (diffusible signal factor). 【Method】 The wild-type Xoc strain Rs105 was used as the parent strain to determine the DSF synthesis level of the mutants and their complementary strains using the rpfCxoc, rpfGxoc and rpfGCxoc (rpfCxoc and rpfGxoc double genes) deletion mutants of suicide vector pK18mobsacB. Extracellular polysaccharide (EPS) yield, morphology and population structure 【Result】 The rpfCxoc and rpfGxoc genes were cloned from the Rs105 genome and the corresponding single or double gene deletion mutants were obtained. Compared with Rs105, ΔrpfCxoc and ΔrpfGCxoc over-synthesized DSF signaling molecules, but the ability of ΔrpfGxoc to synthesize DSF significantly decreased; deletion mutations of rpfCxoc and rpfGxoc single genes or double genes resulted in the loss of pathogenicity of Xoc and decreased the level of EPS synthesis by 34.1% 48.5%, forming a highly aggregated cell membrane biofilm structure. 【Conclusion】 The two-component system of RpfCxoc / RpfGxoc regulates Xoc DSF biosynthesis, EPS production and biofilm dispersal, which are necessary for Xoc to maintain pathogenicity.