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

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.