Bio-priming of rice seeds with novel bacterial strains, for management of seedborne Magnaporthe oryzae L.

Rice blast disease caused by Magnaporthe oryzae is a seed borne which occurs in all rice growing regions of the country (India) causing yield losses up to 40%. In the present study, we report the efficacy of different bacterial strains through seed priming in reducing the blast disease severity under in vitro, in vivo and field conditions. In vitro evaluation revealed that the Bacillus amyloliquefaciens strain UASBR9 and Serratia marcescens strain UASBR4 were found most effective in reducing disease severity (84.28%) compared to reference cultures Bacillus subtilis RBs-1 (72.00%) and Pseudomonas fluorescens RPf-1 (55.24%). The least disease severity and highest seed germination was recorded in seeds bio-primed with B. amyloliquefaciens UASBR9 (0.96 and 98.00%) under in vivo. Bio-priming also activated the induced systemic resistance as evident in the increased activities of peroxidase (0.563/min/g) and polyphenol oxidase (0.825/min/g) defense-related enzymes in comparison with untreated control in rice seedlings upon challenge inoculation with M. oryzae. Field studies showed that seeds bio-primed with B. amyloliquefaciens UASBR9 recorded lowest disease severity (7.0%) of rice blast and increased the grain yield (0.67 kg/m2). Our results indicated that B. amyloliquefaciens UASBR9 could be served as plant growth promoter and an environmental friendly alternative for chemical pesticides to manage rice blast disease.