中文摘要：

十字花科黑腐病菌8004菌株的XC3814基因与致病性和胞外多糖合成有关。文章将XC3814的启动子与报告基因sacB融合,构建了XC3814的表达报告质粒pL3814sac。将该质粒导入野生型菌株8004,获得了报告菌株8004/pL3814sac。利用转座子EZ：：Tn5对报告菌株的基因组进行随机诱变,分离到3株耐蔗糖的突变体。分析发现其中的1株突变体是由EZ：：Tn5插入到编号为XC3882的未知功能的基因所产生的。将由XC3814启动子与报告基因gusA融合得到的报告质粒pGUS3814分别导入8004菌株和XC3882的转座子Tn5gusA5插入突变体,测定比较pGUS3814的GUS表达水平,结果显示在XC3882突变体背景下GUS的表达水平比在野生型背景下降低81.3%,表明XC3814基因的表达水平受XC3882基因的影响。

英文摘要：

Xanthomonas campestris pv. campestris （Xcc） is the causal agent of the black rot disease of cruciferous plants. Our previous work had demonstrated that XC3814 is required for full virulence and extracellular polysaccharide production. In this work, the reporter plasmid pL3814sac was constructed by fusing the promoter region ofXC3814 to the coding region of the gene sacB, and introduced into Xcc wild-type strain 8004. The resulted strain 8004/pL3814sac was mutagenized randomly by the transposon EZ：TnS, and 3 mutant strains insensitive to sucrose were isolated. One of the mutants was due to the disruption of the open reading frame XC3882, which was assigned to code a hypothetical protein. To verify whether XC3882 has an impact on the expression level of XC3814, the reporter plasmid pGUS3814 was constructed by fusing the promoter region of XC3814 to the coding region of the gusA gene. This construct was introduced into the wild-type strain 8004 and the XC3882 mutant strain 190A10, which was derived from the transposon Tn5gusA5 insertion. The GUS activity produced by pGUS3814 in the XC3882 mutant background, was reduced by 81.3 % compared to that in the wild type background. These results indicate that the expression ofXC3814 is influenced by XC3882.