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Characterization of Plant Growth Promoting Rhizobia from Root Nodule of Two Legume Species Cultivated in Assam, India

Singha, Biswajit, Mazumder, Pranab Behari, Pandey, Piyush
Proceedings of the National Academy of Sciences, India, Section B: biological sciences 2018 v.88 no.3 pp. 1007-1016
Bradyrhizobium, Burkholderia, Cajanus cajan, Lablab purpureus, Mesorhizobium, Rhizobium, ammonia, genes, genetic variation, host plants, indole acetic acid, legumes, nitrogen fixation, nodulation, nucleotide sequences, pH, phosphates, phylogeny, plant growth, restriction fragment length polymorphism, ribosomal DNA, root nodules, salinity, solubilization, staining, India
In order to characterize the diversity of plant growth promoting rhizobia associated with legumes cultivated in Assam, 32 bacterial isolates were obtained from the root nodules of Cajanus cajan L and Lablab purpureus L. The isolates were investigated for their morphological, biochemical and plant growth promoting features. The isolates showed similar morphological features such as creamy, white colonies, gram negative staining, rod shape cells but showed variation in the results of biochemical tests. In addition, the isolates produced indole-3-acetic acid, ammonia, solubilized inorganic phosphate and showed varied level of tolerance to acidic pH and high salinity. Present study revealed the presence of nitrogen fixation (nifH) gene and nodulation (nodC) gene in the selected isolates. Restriction fragment length polymorphism (RFLP) analysis of 16S rDNA of the isolates and reference strains revealed a high genetic diversity among them. Basic local alignment search tool (BLAST) analysis of 16S rDNA sequences revealed that isolates from Cajanus cajan L were phylogenetically related to Burkholderia, Mesorhizobium, Rhizobium genera and isolates from Lablab purpureus L were phylogenetically related to Bradyrhizobium genus. The present study also revealed the nodulation and plant growth promoting ability of the isolates on their host plants.