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十字花科黑腐病菌(Xanthomonas campestris pv.campestris,Xcc)的Rpf C/Rpf G双组分系统感应DSF(diffusible signal factor)因子,并通过二级信使环二鸟苷酸(c-di-GMP)调控下游Clp、Zur和FhrR等全局性转录因子。为进一步研究Fhr R在Xcc中的调控作用,本研究构建了编码Fhr R蛋白的XC3027基因的整合突变体PK3027。植株试验表明PK3027突变对致病力和过敏(HR)反应没有影响。将连有hrpG、hrpX、hrp B、hrc U和hrp F启动子的p L6GUS报告质粒导入PK3027中,在XCM培养基中检测gus报告基因表达,结果表明XC3027对这些hrp基因的表达没有影响。表达纯化Fhr R蛋白后进行了凝胶阻滞实验,发现该转录调控蛋白不能直接与hrp X启动子结合。在Xcc8004中FhrR不参与Ⅲ型分泌系统相关基因的调控,并与病原菌致病无关。
The Rpf C / Rpf G two-component system of Xanthomonas campestris pv. Campestris (Xcc) senses the diffusible signal factor (DSF) factor and sequesters two secondary guanine acids (c-di-GMP ) Regulate global transcription factors such as Clp, Zur and FhrR. In order to further investigate the regulatory role of Fhr R in Xcc, we constructed the integrated mutant PK3027 of XC3027 gene encoding Fhr R protein. Plant tests show that the PK3027 mutation has no effect on virulence and allergic (HR) responses. The pL6GUS reporter plasmid with hrpG, hrpX, hrp B, hrc U and hrp F promoters was introduced into PK3027 and the gus reporter gene expression was detected in XCM medium. The results showed that XC3027 had no effect on the expression of these hrp genes. The gel retardation assay was performed after the Fhr R protein was purified and found that the transcriptional regulatory protein could not directly bind to the hrp X promoter. In Xcc8004, FhrR is not involved in the regulation of the genes involved in the type Ⅲ secretion system, and has nothing to do with pathogens.