Exploiting endophytic bacteria for the management of sheath blight disease in rice

Sheath blight of rice caused by Rhizoctonia solani Kuhn is an important soil-borne disease throughout the rice-producing areas of the world. Twenty-nine bacterial endophytes were isolated from different plant sources and tested for their efficacy against R. solani inciting sheath blight in rice. Bacillus subtilis var. amyloliquefaciens (FZB24) caused a maximum 36% inhibition of R. solani over the control in vitro. Rice plants (cv. ADT 39) treated with FZB24, in combination with seed treatment @ 4gkg(-1), seedling dip @ 4gl(-1), soil application @ 500gha(-1) and foliar application @ 500gha(-1), gave the lowest severity of sheath blight (33%) with around 55% reduction over the control under glasshouse conditions. In addition, the B. subtilis (FZB24) treated rice plants showed higher induction of defence-related enzymes, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase, and resulted in higher accumulation of total phenols than in the untreated control plants. The endophyte-treated rice plots had a significantly lower intensity of sheath blight than untreated control plots and also recorded a higher grain and straw yield.