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γ-变形菌纲(γ-Proteobacteria)的黄单胞菌属(Xanthomonas)的大多数种类可引起植物病害,多数是我国检疫对象。与其他革兰氏阴性植物病原细菌一样,植物病原黄单胞菌可通过高度保守的Ⅲ型分泌系统(type-Ⅲsecretion system,T3SS)分泌效应蛋白(T3SS-secreted effectors,T3SEs)进入植物细胞,在非寄主植物和抗病寄主植物上产生过敏反应(hypersensitive response,HR)以及在感病寄主植物上具有致病性。尚不清楚哪些种类的黄单胞菌具有T3SS和缺少哪些T3SE是否可作为检疫的依据。搜集7种检疫性植物病原黄单胞菌,通过PCR和Southern杂交试验结果发现:香蕉细菌性青枯病菌(X.campestris pv.musacearum)的ICMP287和ATCC49084菌株、甘蔗流胶病菌(X.axonopodis pv.vasculorum)ATCC13901菌株、洋葱细菌性叶枯病菌(X.axonopodis pv.allii)的LMG576和LMG578菌株中不含有tale基因,并且ATCC13901菌株既不含有T3SS基因也不含有hpal和xopQ基因;菜豆细菌性疫病菌(X.campestris pv.phaseoli)ATCC49119菌株不含有hpal基因。相应地,推测含有2~12个tale基因的黄单胞菌有:大豆斑疹病菌(X.axonopodis pv.glycines)ICMP5732和ATCC43911菌株、豌豆细菌性疫病菌(X.axonopodis pv.vignicola)ATCC11648菌株、棉花细菌性角斑病菌(X.campestris pv.malvacearum)ATCC12131和(X.campestris pv.phaseoli)ATCC49119菌株。大豆细菌性斑疹病菌ATCC43911菌株尽管含有hpal、xopQ和hrcC基因,但在非寄主烟草上不能激发HR反应;而甘蔗流胶病菌ATCC13901菌株不含有hpal、xopQ和hrcC基因,却激发烟草产生HR反应。这些结果对于分析比较不同植物病原黄单胞菌的致病性因子和设计特定的植物检疫靶点提供了科学线索。
Most species of Xanthomonas of γ-Proteobacteria can cause plant diseases, most of which are quarantine targets in China. Like other Gram-negative phytopathogenic bacteria, plant pathogenic X. aeruginosa enters plant cells via a highly conserved type III secretion system (T3SS), a T3SS-secreting effectors (T3SS) Hypersensitive response (HR) to non-host plants and host plants resistant to disease and pathogenicity on susceptible host plants. It is unclear which types of Xanthomonas have T3SS and which T3SE are missing as a basis for quarantine. Seven species of quarantine plant pathogenic Xanthomonas were collected. The results of PCR and Southern hybridization showed that the ICMP287 and ATCC49084 strains of X. campestris pv. Musacearum, X. axonopodis pv .vasculorum) ATCC 13901 strain, the tale gene is not contained in the LMG576 and LMG578 strains of X. axonopodis pv. allii, and the ATCC 13901 strain neither contains the T3SS gene nor the hpal and xopQ genes; The X. campestris pv. Phaseoli ATCC 49119 strain does not contain the hpal gene. Accordingly, it is presumed that Xanthomonas including 2 to 12 tale genes include X. axonopodis pv. Glycines ICMP5732 and ATCC43911 strains, X. axonopodis pv. Vignicola ATCC 11648 strain , X. campestris pv. Malvacearum ATCC 12131 and X. campestris pv. Phaseoli ATCC 49119 strains. The S. aureus ATCC43911 strain could not stimulate HR response on non-host tobacco despite containing hpal, xopQ and hrcC genes. However, S. canex ATCC 13901 strain did not contain hpal, xopQ and hrcC genes but stimulated the tobacco to produce HR response . These results provide scientific clues for analyzing and comparing the pathogenicity factors of different plant pathogenic Xanthomonas and designing specific phytosanitary targets.