Biological Control of Sheath Blight of Rice using Marine Associated Fluorescent pseudomonads

Abstract

Rice, the crop that gives staple food for India, is being severely affected by several diseases and insect pests. Of these "Sheath Blight" (ShB) disease is one of the economically significant disease that gains serious concern. It is one of the most destructive fungal diseases of rice caused by Rhioctonia solani. It recorded a very high yield loss. Biological control is an efficient disease management strategy. Several microorganisms belong to the genera Bacillus, Pseudomonas, Streptomyces etc are used as "Biological Control Agents" (BCAs) for the management of sheath blight disease in rice. In this scenario, the present work has been aimed to isolate antagonistic rhizobacteria from the least explored coastal sand dune ecosystem, characterize their biological control potential for the suppression of ShB pathogen R. solani and evaluate them in vivo. A total of 46 rhizobacterial strains were isolated from the root hairs of sand dune plant samples using Kings B Agar (KBA) medium. The isolated strains were screened for their antagonist activity against R. solani by using dual culture assay on Potato Dextrose Agar (PDA) medium. About 10 strains were found to have higher in vitro antifungal activity against R. solani i.e., they exhibited zone of inhibition around them. These 10 strains were evaluated for their biocontrol potential in suppressing sheath blight disease in rice using detached leaf bits assay. Five marine associated fluorescent pseudomonad strains such as AMET1102, AMET1104, AMET1133, AMET1133 and AMET1140 have noticeably reduced the ShD incidence in rice leaves.