胡枝子属根瘤菌的多相分类研究

STUDY ON POLYPHASIC TAXONOMY OF RHIZOBIA ISOLATED FROM LESPEDEZA SPECIES

采用了数值分类、全细胞可溶性蛋白电泳分析、ＤＮＡＧ＋Ｃｍｏｌ％和ＤＮＡ相关性的测定以及１６ＳｒＤＮＡＰＣＲＲＦＬＰ分析等多相分类技术对来源于不同地区的１６种寄主的胡枝子根瘤菌进行了系统的分类研究。数值分类的结果表明，在６７％的相似性水平上，全部供试菌可以分为快生型根瘤菌和慢性型根瘤菌两大群，在８０％的相似性水平上又可分为四个亚群。在此基础上，对各亚群的胡枝子根瘤菌进行了ＤＮＡ相关性的测定，以进一步证实和确定它们的分类地位，并通过１６ＳｒＤＮＡＰＣＲＲＦＬＰ分析对各亚群的系统发育关系进行了初步研究。

The diversity of rhizobia isolated from Lespedeza sp p. was determined on the basis of numerical analysis of phenotypic characteristics, sodium dodecyl sulfate polyacry larmide gel electrophoresis (SDS PAGE) of proteins, DNA DNA homology and restriction fragment length polymorphism (RFLP) analysis of 16S ribosomal DNA genes. According to numerical analysis of 125 phenotypic characteristics, strains were divided into two groups at a similarity level of 67%. Group Ⅰ included all the fast growing strains, groupⅡ included all the slow growing strains. Above the similarity level of 80%, four subgroups could be further devided. Subgroup Ⅰ was fast growing rhizobia containing representative strain of Sinorhizobium saheli . Subgroup Ⅱ,Ⅲ,Ⅳ were slow growing rhizobia. Subgroup Ⅱ composed of strains isolated from Lespedeza cuneata in Beijing area and these isolates produced acid in medium containing mannitol. Subgroup Ⅲ included type strain of Bradyrhizobium japonicum . The DNA G+C contents and DNA DNA homology of the members of above four subgroups were determined. The subgroup Ⅰ shared the same DNA homologous group with S.saheli , subgroup Ⅲ belonged to B.japonicum ,subgroup Ⅳ belonged to B elkanii , subgroup Ⅱ was an unique DNA homologous group which showed low level of DNA relatedness with other slow growing rhizobia species. RFLP analysis of 16S rDNA genes verified that the subgroup Ⅱ was a distinctive genealine and showed genetic variation within the strains in it.