Bacillus subtilis strain BS87 as a biocontrol agent against spot blotch disease: effect on growth, nutrient status, and antioxidant enzymes in wheat

Bacillus spp. being rhizospheric bacteria has the potential to provide protection from biotic stresses and also to enhance plant growth. The present study was carried out on bacterial isolate, Bacillus subtilis strain BS87 which has the potential to inhibit several phytopathogens (Bipolaris sorokiniana, Fusarium oxysporum, Fusarium spp., Aspergillus niger, Aspergillus sp., Penicillium sp. and, Rhizoctonia solani) in vitro and is also able to secrete cell-wall-degrading enzymes including protease and chitinase. Isolate BS87, also exhibited several plant growth-promoting traits, such as nutrient solubilization, siderophore, indole-3-acetic acid (IAA), and hydrogen cyanide (HCN) production. Hence, a pot experiment was carried out to evaluate the efficacy of bacterial isolate on plant growth and spot blotch disease in wheat. Results demonstrated that BS87 significantly (p < 0.05) enhanced plant growth and yield in wheat. Chlorophyll content was significantly (p < 0.05) improved when treated with BS87. The spot blotch disease was significantly (p < 0.05) inhibited in wheat by isolate BS87. Lower levels of antioxidant enzymes, including superoxide dismutase, peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase in the plants infected with spot blotch were observed in bacterial-treated plants. BS87 also significantly reduces malondialdehyde and proline contents in diseased plants. BS87 could successfully colonize and persist in the wheat rhizosphere, providing an advantage to the host plant. Therefore, the study suggested that Bacillus subtilis strain BS87 may be used as an effective bioinoculant, enhancing plant growth and controlling spot blotch disease in wheat caused by Bipolaris sorokiniana.