我国中东部地区紫穗槐、紫荆、紫藤根瘤菌的数值分类及16SrDNA PCR-RFLP研究

Numerical Taxonomy and 16SrDNA PCR-RFLP of Root Nodule Bacteria Isolated from the Nodules of Leguminous Trees, Amorpha fruticosa, Cercis racemosa Oliv. and Wisteria (sims) Sweet

从分离自我国中东部地区紫穗槐、紫荆和紫藤 3种宿主根瘤菌中 ,选取 5 9个菌株和 2 9个参比菌株 ,对它们进行了 135个表型性状测定的数值分类分析和 16SrDNAPCR RFLP研究。试验结果表明 ,数值分类聚类在82 %相似性水平上、16SrDNAPCR RFLP聚类在 92 %相似性水平上均聚为 7个群 ,各宿主根瘤菌基本上按参比菌株各属归群。其中绝大多数紫穗槐根瘤菌归属于中慢生根瘤菌属 ,而且在种水平上表现出一定程度的地理环境多样性 ;紫荆根瘤菌基本上属于慢生根瘤菌属 ,在分群方面未表现出明显的地区差异 ;而紫藤根瘤菌则基本上归属于快生菌。其中来自江、浙地区的紫藤根瘤菌与来自其它地区的紫藤根瘤菌存在着明显的地理环境差异 ,并且紫藤根瘤菌较其它 2种宿主根瘤菌表现出较强的抗逆能力 ,如能够耐某些高浓度 (30 0 μg·ml-1)的抗生素 ,可在高盐环境 (3%NaCl)和强碱环境 (pH 11.0 )下生长。这将为我国进行荒山造林、扩种豆科树种提供有意义菌种。另外 ,数值分类结果亦表明 ,以紫穗槐根瘤菌为代表的群 2、以紫荆根瘤菌为代表的群 5和以紫藤根瘤菌为代表的群 7在种水平上均独立成群 。

Fifty nine rhizobial strains, isolated from root nodules of wood legume trees (Amorpha fruticosa, Cercis racemosa Oliv. and Wisteria (Sims) Sweet) in middle and eastern China, were studied by performing analysis of 135 phenotypic characteristics and 16SrDNA PCR RFLP. At the 82% similarity level in numerical taxonomy or at the 92% similarity level in 16SrDNA PCR RFLP, seven groups were clustered. The results indicated that most rhizobial strains from root nodules of Amorpha fruticosa belong to genera Mesorhizobium, and to a greater or lesser extent it also showed a geographical variation; Most rhizobial strains from root nodules of Cercis racemosa belong to genera Bradyrhizobium, but did not show the obvious difference among geographical origins; Most rhizobial strains from root nodules of Wisteria sinensis belong to fast growing rhizobia, and there was an obvious geographical diversity among the strains from Jiangsu, Zhejiang province and other provinces. Meanwhile, most rhizobial strains from root nodules of Wisteria sinensis have high stress resistance. For example, some strains can grow on YMA medium with some higher concentration of antibiotics(300 μg ml -1 ), higher concentration of salt (3%NaCl) or higher alkaline environment (pH 11.0), respectively. In addition, the results also indicated that some strains in group 2, group 5 and group 7 of numerical taxonomy might be new taxa.