Deciphering the mechanism of Trichoderma spp. consortia possessing volatile organic compounds and antifungal metabolites in the suppression of Sclerotium rolfsii in groundnut

Groundnut, one of the oilseed crops is severely infected with necrotropic pathogen Sclerotium rolfsii, incurring huge economic loss to farmers. In the present study, the microbial volatiles (mVOCs) produced by six different Trichoderma spp. was tested for its in vitro efficacy against S. rolfsii IS (BDI)-8 infecting groundnut. Among the six isolates, Trichoderma longibrachiatum T (SP)-20 exhibited the maximum percentage inhibition (84.44%) followed by T (AR)-10 (75.44%) and TNAU TA (75.33%) in dual culture assay against S. rolfsii. Besides, volatiles of T. longibrachiatum T (SP)-20 and T. asperellum T (AR)-10 effectively reduced the mycelial growth of S. rolfsii by 61.11 and 54.44% respectively in paired plate assay. Co culturing of Trichoderma spp. with S. rolfsii produced specific antimicrobial mVOCs viz., Isolongifolan-7-ol and Trans-sesquisabinene hydrate, which could induce plant growth promotion and inhibited the growth of S. rolfsii. Application of consortia of Trichoderma longibrachiatum T (SP)-20 + Trichoderma asperellum T (AR)-10 as seed treatment at 4 g/kg and soil application at 50 g/pot before sowing and at 30 DAS (Days After Sowing), along with mahua oil cake as soil application at 100 g/pot recorded least stem rot disease incidence of 11.34% in pot culture. Besides, upregulation of a novel antifungal metabolite 6-pentyl-2H-pyran-2-one (6-PP) was also noticed in groundnut through GC-MS analysis. Thus, it is concluded that microbial volatiles and metabolites from Trichoderma spp. play an important role in resistance to S. rolfsii in groundnut. •Antimicrobial metabolites from Trichoderma longibrachiatum T (SP)-20 suppressed Sclerotium rolfsii IS (BDI)-8 under in vitro.•T. longibrachiatum T (SP)-20 produced specific mVOCs viz., Isolongifolan-7-ol and Trans-sesquisabinene hydrate with antifungal activity.•Antifungal metabolite 6-pentyl-2H-pyran-2-one (6-PP) identified in groundnut.•RE2522 gene expression and enzymes involved in TCA and terpenoid pathway identified during the bipartite interaction.•Consortia of Trichoderma spp. Along with Mahua cake was effective against stem rot of groundnut.