野油菜黄单胞菌XC3813报告质粒的构建及其表达的初步分析

Construction and preliminary analysis of reported plasmid of XC3813 in Xanthomonas campestris

野油菜黄单胞菌野油菜致病变种(简称Xcc)是引起十字花科作物发生黑腐病的病原菌,在以前的研究中,证实了Xcc8004菌株基因组中一个包含三个基因XC3813-3815的新位点与致病性和胞外多糖(EPS,又称黄原胶)合成有关。将XC3813的启动子与报告基因gusA融合,构建XC3813的报告质粒pRE3813gus。通过分析报告质粒在致病相关基因rpfC、opsX和clp的突变体背景下的表达,发现rpfC和opsX的失活可使报告基因的表达分别降低42.8%和55.7%。这表明XC3813的表达可能直接或间接受rpfC和opsX基因的影响。

Xanthomonas campestris pv. campestris （Xcc） is the causal agency of the black rot disease of cruciferous plants. In previous work a novel locus, XC3813-3815, was identified to be required for full virulence and extracellular polysaccharide （EPS, also called xanthan gum） production. Here the promoter region of XC3813 was fused to the coding region of the gene gusA, resulted the reporter plasmid pRE3813gus. The gusA level of pRE3813gus, determined enzymatically and mirrors XC3813 gene expression, was tested in the wild-type background and the rpfC, opsX or clp gene mutant background. The results showed that the gusA level in rpfC and opsX mutant background was reduced 42. 8% and 55.7%, respectively, compared to that in wild-type background. This indicated that the expression of XC3813 might be regulated directly or indirectly by the gene rpfC or opsX.