Evaluation of actinobacteria for biocontrol of sheath blight in rice

Sheath blight caused by Rhizoctonia solani results in severe yield reduction in rice. Plant genotypes highly resistant to rice sheath blight are not available, which avails opportunity for the exploration of microbial resources for disease management. Actinobacteria were purified from rhizosphere samples to identify potential biocontrol agents. Six isolates with different morphologies showed more than 85% inhibitory activity against R. solani during in vitro screening for antagonism. Further, under greenhouse conditions they caused disease control up to 70% and enhancement in root and shoot length. These isolates exhibited some of the plant growth promoting traits (chitinase, cellulase, nutrient utilization, hormone production, salinity and low water potential tolerance). All the isolates have been identified as Streptomyces sp. based on 16S rRNA sequences. The results indicate the biocontrol of Streptomyces sp. against sheath blight and plant growth promotion potential in rice.