Biocontrol potential of endophytes against Rhizoctonia bataticola: Antifungal activity, metabolite profiling, and plant defense mechanisms

Groundnut (Arachis hypogaea L.), a vital oilseed crop, is highly vulnerable to root rot disease caused by Rhizoctonia bataticola (Taub.) Butler. This study focused on isolating endophytes with antagonistic potential against R. bataticola. Among the isolated endophytes, Bacillus subtilis RMV 3 exhibited the highest inhibition rate (83.33 %) in culture filtrate assays, followed by Trichoderma asperellum RTM 6 (71.85 %). Gas chromatography-mass spectrometry (GC-MS) analysis of secondary metabolites revealed notable compounds, including Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(phenylmethyl)-, which demonstrated strong molecular binding affinities of −7.1 kcal/mol against chitinase and −6.9 kcal/mol against transferase. Under greenhouse conditions, seed treatment and soil application with T. asperellum RTM 6 and B. subtilis RMV 3 significantly improved plant performance, enhancing the vigour index (5613.58) and germination rate (91.23 %), while reducing disease incidence to just 6.7 %. In the health check, the germination rate was (75.32 %) with vigour index (2872.46). Additionally, these treatments induced a pronounced increase in defense-related enzyme activities, including peroxidase (3.49fold increase), polyphenol oxidase (4.73fold increase) and phenylalanine ammonia-lyase (1.88fold increase) over control in groundnut plants. These findings highlight the potential of T. asperellum RTM 6 and B. subtilis RMV 3 as effective biological control agents, offering a sustainable approach to managing root rot in groundnut cultivation.