Antagonistic and Plant Growth Promotion Activities of Endophytic Bacteria Isolated from Deep Water Rice (Oryza sativa L. Cv. Ronga Bao) of Assam

Abstract

Ronga bao is an indigenous deepwater rice (DWR) variety found in flood plains of Brahmaputra valley of Assam is known to possess resistance to flood, drought, salinity and alkalinity. The present study was carried out to investigate on bacterial endophytes isolated from ronga bao and evaluated for antifungal properties against three rice pathogens viz. Rhizoctonia solani, Bipolaris oryzae and Sarocladium oryzae which are responsible for sheath blight, brown spot and sheath rot disease of rice respectively. The plant sample were collected from Lakhimpur district of Assam, followed by isolation of endophytic bacteria from roots, stems and leaves. Invitro antifungal screening was carried out by dual culture technique and cell free culture filtrate (CFCF) of bacterial strains. Four root endophytes and only one stem endophyte showed antifungal activity against the phytopathogens. The plant growth promoting activities were also examined for potential bacterial strains and recorded their responses. Morphological, biochemical and molecular characterization demonstrated that the isolated potent strains were Lysinibacillus fusiformis strain PK4, Enterobacter quasiroggenkampi strain PK2, Shigella sp, Pseudomonas fluorescens strain PK3 and Klebsiella sp. Potential isolates exhibiting the antifungal and plant growth promotion activities may be used for the development of biocontrol formulations for controlling multiple biotic stresses.