Comparative Expression Analysis of Defence-Related Genes in Bacillus-Treated Glycine Max upon Challenge Inoculation with Selective Fungal Phytopathogens

Activation of defence-related genes by the application of beneficial bacteria leads to prior protection against pathogens through induced systemic resistance. The present study was carried out to examine the qRT– PCR-based relative quantification of differently expressed defence-related genes in soybean (Glycine max L. Merrill) plants primed with Bacillus sp. strain SJ-5 against the fungal pathogen Rhizoctonia solani and Fusarium oxysporum. In this context, molecular characterization of plant growth promoting and biocontrol genes of SJ-5 was done by PCR followed by homology analysis. In the GC-MS analysis of SJ-5 volatile organic compounds, potent antifungal compound bis(2-ethyl-hexyl) phthalate and antioxidant compound butylated hydroxy toluene were reported with the highest peak area 47.96% and 21.82% respectively, along with other antifungal compounds in small proportion. Qualitative expression of different defence-related genes like lipoxygenase, phenylalanine ammonia-lyase 2, peroxidase, polyphenol oxidase, endo-1,3-beta-glucanase, catalase, defensin-like protein, vegetative storage protein and chitinase class I was found elicited in the plants primed with SJ-5 against the fungal pathogens. In the qPCR analysis, the highest upregulation was observed in the transcript profile of ppojh2 in the treatments T₅ and T₆ with 4.12- and 4.06-fold increase respectively.