Chitinolytic Bacillus-Mediated Induction of Jasmonic Acid and Defense-Related Proteins in Soybean (Glycine max L. Merrill) Plant Against Rhizoctonia solani and Fusarium oxysporum

In the present research, bacterial-mediated elicitation of induced systemic resistance in the soybean plant was studied. The main objective was in vitro analysis of jasmonic acid and different defense-related enzymes in soybean plants primed with bacterium Bacillus sp. SJ-5 against the fungal pathogen Rhizoctonia solani and Fusarium oxysporum. In the different assays conducted, Bacillus sp. SJ-5 showed strong antifungal activity against R. solani and F. oxysporum showing 45 and 63 % growth inhibition, respectively. Strain SJ-5 was found to be positive for the cell wall-degrading enzymes chitinase, protease, and β-1,3-glucanase, and cell-free supernatant was found with significant fungal growth inhibitory activity. Different defense-related enzymes, namely lipoxygenase, phenylalanine ammonia-lyase, peroxidase, polyphenol oxidase, and β-1,3-glucanase in the different parts of Glycine max L. Merrill were reported to be highest on the 8th day after challenge inoculation and expressed significantly in the root tissue. GC–MS analysis of jasmonic acid (JA) revealed the highest JA accumulation in bacterized soybean plant root tissue challenged with R. solani and F. oxysporum, which was 91.2 and 99.84 %, respectively, with respect to control. In the SJ-5-primed root tissue, phenolic content was highest upon challenge inoculation of R. solani and F. oxysporum with 30.47 ± 0.97 and 32.4 ± 0.3 mg/g fresh weight, respectively. In summary, the present investigation revealed a role for the bacterial isolate Bacillus sp. SJ-5 in soybean plant growth promotion and enhanced protection against R. solani and F. oxysporum by elicitation of defense-related enzymes.