Verification and rapid identification of soybean rhizobia in Indian soils.

Sixty root nodule isolates of soybean rhizobia indigenous to eight field sites in India were characterized using PCR-RFLP for repeated sequence RSalpha a 1195-bp DNA fragment, indole acetic acid production, and nitrogenase activity. Site-dependent variations were observed in terms of IAA production and nitrogenase activities. RSalpha was conserved in slow-growing soybean rhizobia across locations and sites and was absent in other Rhizobiaceae members and other bacterial genera. The results suggest that RSalpha can be a useful molecular marker for slow-growing soybean rhizobia. The study also showed the low presence of soybean nodulating fast growers in Indian soils.