本文選題：十字花科黑腐病菌 + 胞外多糖　； 參考：《廣西大學(xué)》2015年碩士論文

【摘要】：十字花科黑腐病菌(Xanthomonas campestris pv.campestris, Xcc)是黃單胞菌的一個致病變種,能在全球范圍內(nèi)引起所有的十字花科植物產(chǎn)生黑腐病的重要植物病原細菌,也是研究植物病原細菌與植物互作機制的模式細菌之一。Xcc能感染任何時期的十字花科植物,通過水孔或傷口進入,沿葉緣延伸并黑化維管束細胞,最終形成“V”字形黑腐病病斑,黑腐病被認為是世界上最重要、破壞性最強的十字花科植物的疾病,給農(nóng)業(yè)生產(chǎn)帶來巨大的經(jīng)濟損失,然而致病機理還不是很清楚,難以采取對環(huán)境友好且行之有效的預(yù)防治理措施與方法,目前研究植物病原細菌其中包括十字花科黑腐病菌與寄主互作的分子機理仍然是相關(guān)領(lǐng)域的的熱門話題。為了系統(tǒng)性研究Xcc 8004基因的功能,本實驗室構(gòu)建了Tn5gusA5插入突變體庫,篩選出了一批致病力下降的突變株。本研究選取了其中16個編碼假定蛋白的基因,通過構(gòu)建單基因缺失突變體和反式功能互補菌株對這些基因的功能進行分析。首先利用蔗糖敏感性自殺質(zhì)粒pK18mobsacB對Xcc 8004的XC0007、XC0022、XC0048、XC0070、XC0130、XC0225、XC0250、 XC0252、XC0288、XC0386、XC0675、XC3080、XC3605、XC3782、XC3939、 XC4051 基因進行缺失突變,獲得相應(yīng)的突變體菌株D0007、D0022、D0048、 D0070、D0130、D0225、D0250、D0252、D0288、D0386、D0675、D3080、D3605、D3782、D3939、D4051。對所有的突變體進行了胞外蛋白酶、胞外淀粉酶、胞外纖維素酶、胞外多糖、游動性及致病性進行了檢測,結(jié)果表明,D3605與Xcc 8004野生型相比,突變體D3605胞外多糖合成能力明顯下降,游動性明顯減弱,致病性顯著降低,積聚形成生物膜的能力顯著增強；在辣椒葉片ECW10-R的過敏反應(yīng),在NYGB培養(yǎng)基、MMX培養(yǎng)基中生長均不受影響；其余基因的突變體與野生型Xcc 8004相比,致病性及各種表型均無明顯差異,說明另外15個基因在已檢測的表型和致病過程中沒有作用,或者所起的作用微弱。生物信息學(xué)分析得,XC3605含有兩個結(jié)構(gòu)域Glyco_tran_WbsX(O-抗原合成相關(guān)糖基轉(zhuǎn)移酶),RgpF(鼠李糖-葡萄糖多糖裝配相關(guān)蛋白因子F),二者都與脂多糖(LPS)合成相關(guān),并且在黃單胞菌屬中比較保守。將完整的XC3605編碼區(qū)及啟動子區(qū)克隆到p LAFRJ上,導(dǎo)入到D3605中獲得功能互補菌株C3605。C3605胞外多糖產(chǎn)量、游動性、致病力和生物被膜均恢復(fù)到野生型水平,說明XC3605與Xcc 8004胞外多糖合成,游動性,致病力,生物膜相關(guān)。研究結(jié)果表明,XC3605基因在十字花科黑腐病菌致病過程中發(fā)揮重要作用。
[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，

本文編號：1800287