攀枝花市银合欢根瘤菌遗传多样性

Genetic diversity of the rhizobia isolated from Leucaena leucocephalaeucocephala in Panzhihua city

摘要:

【目的】研究分离自四川攀枝花的银合欢根瘤菌的遗传多样性。【方法】采用联合16S rDNA RFLP和IGS RFLP的综合聚类分析(16S-IGS RFLP)、AFLP及多位点持家基因(16S rDNA，atpD，recA)序列的联合分析对供试银合欢根瘤菌进行研究。【结果】31株未知菌具有15种16S-IGS遗传图谱类型、27种AFLP类型。16S-IGS RFLP结果表明，没有未知菌与Bradyrhizobium的参比菌株聚在一起。在71.4%的相似水平上，31个未知菌按属的水平分成3个分支：S、M和R，分别分布在Sinorhizobium属(28株)、Mesorhizobium属(2株)和Rhizobium属(1株)。S分支的28个菌在84%的相似水平上，16S-IGS RFLP聚类图中构成3个群：群S1、群S2、群S3；在AFLP聚类图中构成9个AFLP群：S1–S9。多位点基因序列表明，代表菌株SCAU215、SCAU231分别与M. Plurifarium、R. huautlense亲缘关系最近。而分布于Sinorhizobium属SCAU222和SCAU228、SCAU213、SCAU216可能代表Sinorhizobium的3个新类群。【结论】攀枝花市银合欢根瘤菌遗传多样性丰富，分布于Sinorhizobium、Mesorhizobium和Rhizobium三个属，且优势类群为Sinorhizobium。

Abstract:

[Objective] Genetic diversity and relationship of the rhizobia isolated from Leucaena leucocephala in Panzhihua City of Sichuan were analyzed. [Methods] We studied genetic diversity of these isolates with combined RFLP patterns of 16S rDNA and IGS (16S-IGS RFLP), AFLP fingerprinting, and constructed 16S rDNA, atpD, recA gene phylogenetic trees and phylogenetic tree based on the concatenated sequences of the three genes. [Results] Fifteen distinct 16S-IGS genotypes and 27 AFLP genotypes were distinguished among the 31 isolates based on 16S-IGS RFLP and AFLP, respectively. In 16S-IGS RFLP dendrogram, all isolates were not clustered with Bradyrhizobium reference strains, but were grouped into three groups such as genus level required at similarity level of 71.4% for Sinorhizobium (28 isolates, S group), Mesorhizobium (2 isolates, M group), Rhizobium (1 isolate, R group). At similarity of 84%, 28 Sinorhizobium strains were divided into three, nine clusters in 16S-IGS RFLP, AFLP dendrograms, respectively. Analyses of multi-locus housekeeping genes of 16S rDNA, atpD and recA indicated representative strains SCAU215, SCAU231 were closely related to M. Plurifarium, R. huautlense, nevertheless SCAU222 and SCAU228, SCAU213, SCAU216 might represent three new Sinorhizobium groups. [Conclusion] The rhizobia isolated from L. leucocephala in Panzhihua City had rich genetic diversity, these isolates were assigned as Sinorhizobium, Mesorizobium and Rhizobium, and Sinorhizobium was the predominant genus.