Untangling the metabolome of resistant (VBN4) and susceptible (CO5) blackgram cultivar bacterized with Bacillus pumilus imparts resistance response against yellow mosaic disease

Abstract

Mungbean yellow mosaic virus (MYMV), a begomovirus transmitted by the whitefly Bemisia tabaci, is one of the most destructive pathogens affecting blackgram (Vigna mungo), causing substantial yield losses across India. In the present study, MYMV inoculum was established in the susceptible cultivar CO5 via viruliferous whitefly transmission and confirmed through PCR amplification of the coat protein (CP) gene. Comparative screening of resistant (VBN4) and susceptible (CO5) cultivars validated the complete resistance of VBN4 (RC) and high susceptibility of CO5 (SC). Twenty bacterial endophytes and rhizosphere isolates were evaluated for their antiviral potential under controlled conditions. Among these, Bacillus pumilus SVR1 demonstrated complete suppression of MYMV symptoms with 0 % PDI as against 80 % PDI in untreated control, delayed symptom onset, and significant enhancement of plant growth in comparison with control. Untargeted GC-MS metabolite profiling revealed that SVR1-treated infected plants accumulated higher levels of defense-associated metabolites, including phenolic compounds, unsaturated fatty acids, and inositol derivatives. KEGG pathway enrichment indicated the involvement of linoleic acid metabolism, glycerolipid metabolism, and inositol phosphate metabolism in antiviral defense. Furthermore, molecular docking analysis identified soyasapogenol-B as the most potent antiviral candidate, exhibiting high binding affinity (−9.0 to −7.4 kcal/mol) against multiple MYMV proteins, including CP, Rep, MP, and TrAP, suggesting a multi-target inhibitory mechanism. This integrated approach, combining biological control, metabolomics, and in silico molecular docking is distinct and the first of its kind for MYMV management.