十字花科黑腐病菌XC3605基因功能鉴定

发布时间：2018-04-25 07:09

  本文选题：十字花科黑腐病菌 + 胞外多糖　； 参考：《广西大学》2015年硕士论文

【摘要】：十字花科黑腐病菌(Xanthomonas campestris pv.campestris, Xcc)是黄单胞菌的一个致病变种,能在全球范围内引起所有的十字花科植物产生黑腐病的重要植物病原细菌,也是研究植物病原细菌与植物互作机制的模式细菌之一。Xcc能感染任何时期的十字花科植物,通过水孔或伤口进入,沿叶缘延伸并黑化维管束细胞,最终形成“V”字形黑腐病病斑,黑腐病被认为是世界上最重要、破坏性最强的十字花科植物的疾病,给农业生产带来巨大的经济损失,然而致病机理还不是很清楚,难以采取对环境友好且行之有效的预防治理措施与方法,目前研究植物病原细菌其中包括十字花科黑腐病菌与寄主互作的分子机理仍然是相关领域的的热门话题。为了系统性研究Xcc 8004基因的功能,本实验室构建了Tn5gusA5插入突变体库,筛选出了一批致病力下降的突变株。本研究选取了其中16个编码假定蛋白的基因,通过构建单基因缺失突变体和反式功能互补菌株对这些基因的功能进行分析。首先利用蔗糖敏感性自杀质粒pK18mobsacB对Xcc 8004的XC0007、XC0022、XC0048、XC0070、XC0130、XC0225、XC0250、 XC0252、XC0288、XC0386、XC0675、XC3080、XC3605、XC3782、XC3939、 XC4051 基因进行缺失突变,获得相应的突变体菌株D0007、D0022、D0048、 D0070、D0130、D0225、D0250、D0252、D0288、D0386、D0675、D3080、D3605、D3782、D3939、D4051。对所有的突变体进行了胞外蛋白酶、胞外淀粉酶、胞外纤维素酶、胞外多糖、游动性及致病性进行了检测,结果表明,D3605与Xcc 8004野生型相比,突变体D3605胞外多糖合成能力明显下降,游动性明显减弱,致病性显著降低,积聚形成生物膜的能力显著增强；在辣椒叶片ECW10-R的过敏反应,在NYGB培养基、MMX培养基中生长均不受影响；其余基因的突变体与野生型Xcc 8004相比,致病性及各种表型均无明显差异,说明另外15个基因在已检测的表型和致病过程中没有作用,或者所起的作用微弱。生物信息学分析得,XC3605含有两个结构域Glyco_tran_WbsX(O-抗原合成相关糖基转移酶),RgpF(鼠李糖-葡萄糖多糖装配相关蛋白因子F),二者都与脂多糖(LPS)合成相关,并且在黄单胞菌属中比较保守。将完整的XC3605编码区及启动子区克隆到p LAFRJ上,导入到D3605中获得功能互补菌株C3605。C3605胞外多糖产量、游动性、致病力和生物被膜均恢复到野生型水平,说明XC3605与Xcc 8004胞外多糖合成,游动性,致病力,生物膜相关。研究结果表明,XC3605基因在十字花科黑腐病菌致病过程中发挥重要作用。
[Abstract]:Xanthomonas campestris pv.campestris (Xccstris) is a pathogenic variety of xanthomonas, which can cause black rot of all cruciferous plants worldwide. Xcc is also one of the model bacteria that study the interaction between plant pathogenic bacteria and plants. Xcc can infect cruciferous plants at any time, enter through water holes or wounds, extend along the leaf margin and darken vascular bundle cells. "V" -shaped black rot is finally formed. Black rot is considered to be the most important and destructive disease of cruciferous plants in the world, which brings huge economic losses to agricultural production, but the mechanism of the disease is not very clear. It is difficult to take environmentally friendly and effective preventive measures and control measures. At present, it is still a hot topic in related fields to study the molecular mechanism of interaction between plant pathogenic bacteria, including cruciferous black rot bacteria and their hosts. In order to systematically study the function of Xcc 8004 gene, a Tn5gusA5 insertion mutant library was constructed and a number of mutants with decreased pathogenicity were screened. In this study, 16 genes encoding hypothetical proteins were selected, and the functions of these genes were analyzed by constructing single gene deletion mutants and trans functional complementary strains. 棣栧厛鍒╃敤钄楃硸鏁忔劅鎬ц嚜鏉，

本文编号：1800287