Six orange-pigment-producing endophytic and epiphytie bacterial strains were isolated from four of ten kinds of economic plant root. The genetic diversity of these 6 strains was analyzed using BOX-PCR genomic fingerprint technique which divided the 6 strains into 3 genetic groups. The taxonomic position of representative strains of the three genetic groups was determined using phylogenetic and phenotypic analysis which indicated the 3 representative strains were all Pseudomonas chlororaphis subsp, aureofaciens. Thinlayer chromatography analysis showed the pigment excreta of the 3 representative strains consisted of exactly the same composition. Eleetrospray ionization mass spectrometry and nuclear magnetic resonance analysis confirmed the major pigment component as Phena- zine-1-carboxylie Acid （PCA） , and its antifungal activity was analysed also. Conclusion： There existed notable diversity at strain level of PCA-producing Aureofaciens from plant root. The strain diversity showed corresponding relationship with the geographical environment diversity and host plant diversity, among them the 3 endophytic strains LJ1, GL1 and TC1 had the potential to be processed into living-bacteria preparation and applied to bio-proteetion of host plants due to their close relationship.%从新疆和北京两地的十余种经济植物中的4种植物的根部分离筛选到6株可向培养基中分泌橙黄色色素物质的根内内生菌和根表附生菌，采用BOX—PCR基因组指纹图谱扩增技术对这6株细菌的遗传多样性进行了分析，结果表明这6株细菌可以划分为3个遗传群。采用系统发育和表型分析相结合对这3个遗传群的代表菌株的分类地位进行了鉴定，结果表明3个代表菌株均为绿针假单胞菌致金色假单胞菌亚种（P$eUdomonoschlororo础如subsp．aureofaciens）。采用薄层层析对3个代表菌株的色素分泌物组成进行了分析，结果显示3个代表菌株的色素分泌物组成完全相同。进一步采用电喷雾质谱和核磁共振分析确认色素主要组分为吩嗪-1-羧酸（Phenazine-1．carboxylicAcid，PCA），并对其抗真菌活性进行了分析。结论：植物根部产吩嗪羧酸抗生素的致金色假单胞菌在菌株水平上存在着显著的多样性，这种多样性与其地理分布的多样性和宿主植物的多样性之间存在着一定程度的对应关系，其中的3株内生细菌LJ1、GL1、TC1由于与宿主植物存在极为密切的关系而有可能作为生物活体农药直接应用于宿主植物病害的生物防治，显示了很好的应用潜力。
展开▼
