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十字花科黑腐病菌(Xcc 8004)中一对双组份系统hpa S/hpa R2在致病过程中有重要作用,以前的研究发现,XC2388的表达可能受XC3669/XC3670的调控。为分析XC2388的功能,本试验采用p K18mob Sac B介导的同源双交换的方法构建缺失突变体,对新获得的缺失突变体DM2388的分析发现,XC2388突变后,病原菌对寄主萝卜叶的致病力与野生型相比降低80%,采用PCR扩增XC2388完整的ORF,将新获得的1 349 bp的DNA片段克隆在p LAFR3质粒上,将新获得的重组质粒导入DM2388,发现互补菌株CDM2388的致病力可以恢复至野生型的60%,表明XC2388与致病性相关。以MMX培养基为介质绘制生长曲线,经分析发现突变体的生长严重受阻,在培养基中加入Thr后可以恢复生长,表明DM2388可能是与Thr合成相关的营养缺陷性菌株。
A two-component system hpa S / hpa R2 in C. crucifera (Xcc 8004) plays an important role in pathogenicity. Previous studies have found that the expression of XC2388 may be regulated by XC3669 / XC3670. In order to analyze the function of XC2388, a deletion mutant was constructed by using pK18mob Sac B-mediated homologous double exchange. The analysis of the newly obtained deletion mutant DM2388 showed that after XC2388 mutation, The pathogenicity was reduced by 80% compared with the wild type. The complete ORF of XC2388 was amplified by PCR. The newly obtained 1 349 bp DNA fragment was cloned into p LAFR3 plasmid and the newly obtained recombinant plasmid was introduced into DM2388. The complementation strain CDM2388 Of the pathogenicity can be restored to 60% of wild-type, indicating that XC2388 and pathogenicity. Growth curves were drawn with MMX medium as medium. The results showed that the growth of the mutants was severely hampered, and the growth of the mutant could be restored by adding Thr into the medium. This indicates that DM2388 may be an auxotrophic strain associated with Thr synthesis.