中文摘要：

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Fhr R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hrp G、hrp X、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Xcc 8004中Fhr R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。

英文摘要：

In Xanthomonas campestris pv. campestris （Xcc）, the two-component signal transduction system RpfC/RpfG percepts DSF （diffusible signal factor） signal and modulates the downstream DSF global transcription regulators such as Clp, Zur and FhrR by changing the second messenger cyclic di-GMP （c-di-GMP）. To further study the regulation function of FhrR in Xcc, we constructed the integrated mutant PK3027 of XC3027 which encoded FhrR protein. The plant assay showed that PK3027 mutation didn＇t affect the virulence and hypersensitive reaction （HR） significantly. The reporter plasmid pL6GUS carrying the promoter of hrpG, hrpX, hrpB, hrc U, and hrpF were transferred into PK3027, respectively. The expression of gus reporter gene was measured in the XCM medium, the results of which indicated that XC3027 did not affect the expression of these hrp genes. In addition, the gel retardation experiments were carried out after the purification of FhrR protein, which found that FhrR protein could not bind to the hrpX promoter directly. In conclusion, the FhrR might not be involved in the regulation of IlI type secretion system related genes and might not be associated with pathogen pathogenesis in Xcc 8004.