16SrRNA基因测序确定根瘤菌的系统发育

采用聚合酶链反应和ＤＮＡ测序技术分析了两个新根瘤菌群的代表菌株的部分１６ＳｒＲＮＡ基因序列，并对所得序列进行了聚类分析。在系统发育树状图中，菌株ｓｈ２２６２３所代表的根瘤菌群与菜豆根瘤菌、豌豆根瘤菌及发根土壤杆菌等构成一个亚群，另一个菌群的代表菌株ｓｈ１９３１２与土壤杆菌的３个种构成一亚群。这些结果初步确定了两菌群的系统发育地位，并提示了根瘤与土壤杆菌两属间进化上的密切关系。

Phylogeny of Two Novel Rhizobial Groups Isolated from the Loess Plateau

The partial 16S rRNA gene sequences of strain sh2262 3 and sh19312 representing two uniquerhizobium groups from the Loess Plateau were determined and compared with their relatives. Thephylogenetic tree was constructed and it showed that these two strains distinguished from all of describedspecies.Strain 19312 was clustered with 3 species of Agrobacterium,and far from any species of Rhizobium. Strain 22623 was closely related to R. etli,and belonged to the subgroup formed by most of Rhizobium species. These results demonstrated that the tested strains represented two novel genealines in familyRhizobiaceae.