Phylogeny and Potentiality of Indigenous Micro-Symbionts Nodulating Mungbean in San Mateo, Philippines

San Mateo serves as the mungbean capital of the Philippines. However, it lacks information concerning indigenous microsymbiont that could be exploited to sustain mungbean production. This study aimed to evaluate the phylogeny and symbiotic potential of indigenous nodule bacteria in San Mateo, Philippines. A total of 183 bacterial strains were isolated from mungbean nodules established in the area. The isolates were grouped into 9 distinct morpho-biochemical clusters, coded as MB1–MB9. Thereafter, a representative isolate for each cluster was subjected to 16S rRNA gene sequencing. Phylogeny of the sequences revealed that the isolates are distributed to diverse bacterial genera namely Bradyrhizobium, Rhizobium, Pseudomonas, Bacillus, Agrobacterium, Stenotrophomonas and Leifsonia. Interestingly, both isolates MB1 (Bradyrhizobium) and MB7 (Rhizobium) induced nodulation in mungbean after authentication tests. Unlike previous reports, this study confirms that Rhizobium strains also harbors nodulating trait and establishes symbiotic relationship with mungbean in tropical soils. Furthermore, inoculation trial revealed that native strain MB1 and MB7 lead to a significant increase in leaf N-accumulation, nodulation and shoot yield with corresponding symbiotic scores of 94.32 and 39.70% respectively. These results suggest the remarkable symbiotic performance of local strains isolated, which could be utilized to further boost mungbean production in the municipality.