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为了阐明水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)利用DSF信号群体感应(QS)系统对毒性表达进行调控的机理,本研究对编码QS的rpf基因进行了分子鉴定,分析了Δrpf基因突变体在水稻叶组织中的种群量变化,利用RT-qPCR方法定量测定了编码T3SS的hrp基因转录本以及rpf基因自身表达。结果表明,rpfF、rpfC和rpfG基因与几种主要植物病原黄单胞菌同源序列高度保守;RpfF是烯脂酰辅酶A水合酶家族成员之一,RpfC含有组氨酸磷酸激酶结构域(His-KA)和磷酸受体结构域(REC),RpfG含有REC和HD-GYP结构域;Δrpf突变体在水稻叶组织中的种群量及其扩展能力均明显下降;hrp基因转录显著地受到QS调控;rpf基因表达与Xoo种群密度密切相关。因此,Xoo QS系统显著地调控了hrp基因的表达,在QS与T3SS表达之间存在一个信号通路。
In order to elucidate the mechanism by which Xanthomonas oryzae pv. Oryzae (Xoo) controls the virulence of expression using the DSF signal QS system, the rpf gene encoding QS was molecularly identified and the Δrpf gene The population variation of the mutant in rice leaf tissue was measured. The RT-qPCR method was used to quantitatively determine the transcript of hrp gene encoding T3SS and the expression of rpf gene itself. The results showed that the rpfF, rpfC and rpfG genes are highly conserved among several major plant pathogenic Xanthomonas homologs. RpfF is a member of the enone acyl-CoA hydratase family. RpfC contains histidine phosphate kinase domain (His -Ka) and the phosphate receptor domain (REC). RpfG contained REC and HD-GYP domains. The Δrpf mutant significantly decreased the population and its expandability in rice leaf tissue. The transcription of hrp gene was significantly regulated by QS ; rpf gene expression is closely related to Xoo population density. Therefore, the Xoo QS system significantly regulates the expression of the hrp gene, with a signaling pathway between QS and T3SS expression.