Genetic characterization of Burkholderia cepacia strain from Northeast India: A potential bio-control agent

This paper reports the characterization of naturally occurring rhizobacteria from NE India for the control of wilt and damping-off diseases in French beans. French bean (Phaseolus vulgaris L.) is one of the most important food legumes for direct human consumption which was originated from South and Central America. In NE India wilt and damping-off in beans are serious diseases which are mainly caused by Fusarium spp and Rhizoctonia solani. Out of 625 bacterial isolates obtained from French bean growing fields of Manipur, 15 potential isolates were selected, whose inhibition zone width were more than 15 mm. Strain IBSD-LKBI exhibited strong antagonistic activity and can inhibit both the pathogens. Besides, this strain also produced extracellular hydrolytic enzymes (protease, chitinase, β-1, 3-glucanase), secondary metabolites (Siderophore, HCN). It also produces plant growth promoting hormone (IAA) and can solubilize organic phosphate. Burkholderia cepacia IBSD-LKBI exhibited the highest plant growth promotion and BCA. After 60 days of treatment, plant height, root length, fresh weight and % of disease suppression were significantly (P < 0.05) higher than in control plants. Productions of secondary metabolites were detected using gene specific primer. This bacterium was phenotypically characterized and sequence data of 16S rDNA revealed the closest identity with Burkholderia cepacia (98%). Multiple sequence alignment & phylogram with closely related sequence accessions using MEGA Software revealed this naturally occurring biocontrol bacteria belongs to Burkholderia cepacia complex genomovar I based on the Biolog identification system with 16S rDNA gene sequence analysis. This organism is one of the new reports from NE India for the control of wilt and damping-off diseases in French beans.