Biological control of wheat blast disease by seed endophytic probiotic Bacillus species and bacterial secondary metabolites

The destructive wheat blast disease, caused by the fungus Magnaporthe oryzae Triticum (MoT), poses a serious threat to food and nutritional security of many countries including Bangladesh, Zambia, Brazil, Argentina, Bolivia and Paraguay. This study aimed to discover antagonistic seed endophytic bacteria and bacterial metabolites for biological control of wheat blast. Out of 750 endophytic bacteria, three viz. Bacillus subtilis subspecies subtilis BTS3, B. velezensis BTS4 and B. velezensis BTLK6A strongly inhibited hyphal growth and developmental transitions of MoT. Out of 120 secondary metabolites from Bacillus and Streptomyces species, eleven compounds including linear lipopeptides (e.g., gageopeptides A-D, gageotetrin B), inhibitor of ATP synthase (e.g., oligomycins), protein kinase inhibitor (e.g., staurosporine, chelerythrine chloride), and macrolides (bonactin, and feigrisolide C) significantly inhibited mycelial growth, production of conidia and formation of appressoria of MoT. Application of both endophytic bacteria and bacterial metabolites provided 65–90% protection of field-grown wheat when they were artificially inoculated with conidia of MoT. Genomics analysis (https://doi.org/10.6084/m9.figshare.5558641.v1) revealed that biocontrol of wheat blast by the probiotic bacteria wasassociated with antibiosis and ISR in wheat plants. Further large-scale field studies are needed for developing effective formulations of the bacterial endophytes and secondary metabolites for the biocontrol of wheat blast as novel biologicals. ; No Full Text