根瘤菌参比菌株23S rRNA基因数量和定位及其系统发育群

    为了明确23S rRNA基因数量和定位是否可更好地揭示根瘤菌参比菌株的系统发育关系,采用I-CeuI酶切和脉冲场凝胶电泳(PFGE)结合的方法,对根瘤菌株23S rRNA基因的数量和定位进行分析,并依据其相似性进行聚群.结果显示.根瘤菌参比菌株可聚为19个系统发育群.其中,在属的水平上,13个系统发育群与现行分类群(不包括依据16S rRNA基因序列分析结果)一致,6个不一致.在种的水平上,现行分类群中同种的根瘤菌可进一步细分为不同的系统发育群.这表明:I-CeuI酶切和PFGE结合的方法能从基因组特征角度对根瘤菌参比菌株进行更加细化的系统发育分类,并使其属种间的同质性更好.

Phylogenetically clustering of rhizobial reference strains based on numbers and location of their 23S rRNA genes

To clarify phylogenetic relationships among rhizobial reference strains,the numbers and location of their 23S rRNA genes were analyzed by pulsed field gel electrophoresis(PFGE) after I-CeuI cleavage.According to the similarity in the numbers and location of their 23S rRNA genes,rhizobial reference strains were grouped into 19 phylogenetic clusters.Of which,13 clusters were consistent with taxonomic groupings(taxa) in genera level,but 6 clusters not.The clustering method based on the numbers and location of rhizobial 23S rRNA genes also divided the rhizobia belonging to the same taxa into different phylogenetic clusters.These results suggest that identification of genomic features using PFGE after DNA cleavage with I-CeuI can further characterize current rhizobial taxa into different phylogenetic clusters with a high genetic homogeneity inside clusters.