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【目的】旨在阐明3个DSF/Rpfxoo信号系统成员RpfFxoo、RpfCxoo和RpfGxoo在水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)毒性表达中的功能。【方法】用标记置换法缺失突变rpfFxoo、rpfCxoo和rpfGxoo基因,测定突变体及其互补菌株的DSF(diffusible signal factor)信号分子产生、胞外多糖(EPS)产生及其对水稻的致病性。【结果】从野生型菌株PXO99A基因组中克隆了推测与DSF信号生成和传导有关的基因rpfFxoo、rpfCxoo和rpfGxoo,获得了相应的单基因或双基因缺失突变体。与PXO99A产生DSF相比,ΔrpfFxoo、ΔrpfF+Cxoo和ΔrpfF+Gxoo均不产生DSF,ΔrpfCxoo过量产生,ΔrpfGxoo产量降低;rpfFxoo、rpfCxoo和rpfGxoo可以分别互补Xoo和Xcc的相应基因突变体,恢复DSF产生表型。除ΔrpfFxoo的EPS产生无明显变化外,其余突变体的均显著减少。所有突变体对水稻的致病性均显著下降。【结论】RpfFxoo、RpfCxoo和RpfGxoo调控了Xoo的DSF信号生成、EPS产生和致病性。
【Objective】 To elucidate the function of RpfFxoo, RpfCxoo and RpfGxoo in three DSF / Rpfxoo signaling systems in the virulence of Xanthomonas oryzae pv. Oryzae (Xoo). 【Method】 Mutations of rpfFxoo, rpfCxoo and rpfGxoo genes were deleted by marker replacement method, and the production of diffusible signal factor (DSF) and the production of extracellular polysaccharides (EPS) and their pathogenicity to rice were tested. 【Result】 The results showed that rpfFxoo, rpfCxoo and rpfGxoo, which were deduced to be involved in DSF signal transduction and transduction, were cloned from the wild-type strain PXO99A and the corresponding single or double gene deletion mutants were obtained. Compared with PXO99A-producing DSF, neither ΔrpfFxoo, ΔrpfF + Cxoo nor ΔrpfF + Gxoo produced DSF, and ΔrpfCxoo was overproduced and ΔrpfGxoo production was reduced. RpfFxoo, rpfCxoo and rpfGxoo could complement the corresponding gene mutants of Xoo and Xcc respectively and restore the DSF production table type. Except for ΔrpfFxoo, no significant changes were found in EPS production, while the other mutants were significantly reduced. The pathogenicity of all the mutants to rice decreased significantly. 【Conclusion】 RpfFxoo, RpfCxoo and RpfGxoo regulate Xoo’s DSF signal generation, EPS production and pathogenicity.