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 beta-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 beta-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.