Efficacy of Bacillus tequilensis strain JN-369 to biocontrol of rice blast and enhance rice growth

Rice blast caused by Magnaporthe oryzae is one of the major threat to global food security. In this study, Bacillus tequilensis strain JN-369, which exhibited antagonistic effect against several phytopathogens, was previously isolated and identified from xiangzaoxian No. 24 healthy rice plants. To further evaluate its potential agricultural use, in vitro on detached leaves test, greenhouse and field experiments were performed to evaluate the plant growth-promotion and biocontrol efficacy of strain JN-369. The results of the study showed that strain JN-369 can promote seed germination and seedling plant growth, and improve plant defense enzyme activities. Compare with water treatment, the plant height, stem width, root length, fresh weight of above-ground, fresh weight of root, chlorophyll a, chlorophyll b, total chlorophyll, root activity, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) of rice seedlings increased by 37.49%, 6.25%, 56.76%, 67.87%, 55.25%, 149.60%, 31.09%, 109.04%, 53.66%, 353.17%, 284.30% and 104.86%, respectively. Moreover, strain JN-369 also has good biocontrol effect on rice blast. The biocontrol effect of the protective test and the therapeutic test reached up to 74.08% and 62.96% on detached rice leaves, respectively. JN-369-treated rice plants showed significantly decrease in disease index in greenhouse experiment. And significantly reduced rice leaf blast and panicle blast severity and increased its yield under field conditions. In summary, B. tequilensis strain JN-369 may be developed as a potential biocontrol agent against rice blast as well as a biofertilizer for rice cultivation.