Deciphering the potential of biocontrol agents for managing mycotoxin in chickpea: Mechanistic insights and functional dynamics

Plants are constantly exposed to wide variety of soil-borne phytopathogens, with Fusarium oxysporum being a major obstacle to crop productivity. Conventional control methods primarily rely on fumigants and chemical pesticides, which disrupt soil microbial communities and the ecosystem balance. When pathogens infect, plants activate stress responses such as strengthening of cell walls, regulation of reactive oxygen species, and production of antimicrobial compounds, often through metabolic reprogramming. Given the limitations of chemical pesticides and the soil-borne nature of the pathogen, this study investigates the mechanism of biocontrol agents (BCAs) as a sustainable strategy for managing Fusarium wilt in chickpea (Cicer arietinum). Two BCAs, Paenibacillus lentimorbus (NBRI-CHM12) and Bacillus amyloliquefaciens (NBRI-SN13), were tested for their antagonistic effects against F. oxysporum. Their effectiveness was evaluated under both greenhouse and microplot conditions to understand their role in disease suppression. Metabolomic analysis of chickpea plants identified specific saccharide derivatives linked to each BCA. CHM12 was associated with fructose, glucose, galactose, ribofuranose, glucopyranoside, xylopyranose, malic acid, arabitol, ribitol, hexadecanoic acid, and oleic acid; while, SN13 was linked with mannose, xylofuranose, sorbopyranose, glucopyranoside, galactopyranoside, xylitol, and trimethyl ester of glucitol. These findings indicate different defense mechanisms activated by each BCA. Both BCAs modulated cell wall hydrolases and antioxidant systems, improved soil microbial health, and notably decreased Fusarium-associated zearalenone levels in seeds by 77.3 % (CHM12) and 77.5 % (SN13) under greenhouse conditions. Overall, the results revealed the distinct pathways by which P. lentimorbus and B. amyloliquefaciens work and demonstrated their potential as biopesticides for sustainable control of Fusarium wilt in chickpea.