Relationships between the Diversity of Acacia Rhizobia and the Tree Growth Characteristics and the Environmental Conditions

The aim of this work was to investigate the relationships between the diversity of Acacia rhizobia and the tree growth characteristics and the environmental conditions. In this study, we isolated 45 rhizobia strains from three Acacia species in Guangxi, China. 16S rRNA sequencing analysis and phylogenetic analysis were performed for the 45 rhizobia stains with 20 other strains as references. These rhizobia strains were phylogenetically classified as four genera with 35.6% as Bradyrhizobium, 31.1% as Mesorhizobium, 13.3% as Rhizobium, and 20% as Agro bacterium. Among the 15 Acacia crassicarpa strains, 86.7% were Bradyrhizobium and 13.3% of them were Mesorhizobium. The 15 strains from A.mangium × A.auriculiformis 80% were Mesorhizobium and 20% were Bradyrhizobium. The 15 strains of Acacia confusa 40% were Rhizobium and the rest 60% were Agro bacterium. The study indicates that the diversity of Acacia rhizobia strains is tightly correlated with the growth characteristics of Acacia and the ecological factors.