Antagonistic activity of native Trichoderma spp. against Moniliophthora roreri and volatile metabolite profiling of the most active strain in Amazonas, Peru

Cacao ( Theobroma cacao L.), known as the “food of the gods”, is a crop of major nutritional and economic importance. Trichoderma spp. are promising biocontrol agents against frosty pod rot caused by Moniliophthora roreri , which can reduce yields by up to 100% under poor management. In this study, ten native Trichoderma strains from Amazonas, Peru, were evaluated for antifungal activity in vitro. Both volatile organic compounds (VOCs) and non-volatile organic compounds (nVOCs) produced during co-culture inhibited M. roreri. Strain BIF7-C1 showed the strongest inhibition among VOC assays (45.5%), while strain BIF14-C2 exhibited the highest nVOC effect (22.3%). Because of its superior performance, strain BIF7-C1 was selected for volatile profiling using solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Two SPME fibers were employed: Carboxen/Divinylbenzene/Polydimethylsiloxane (CAR/DVB/PDMS) and Carboxen/Polydimethylsiloxane (CAR/PDMS). With the CAR/DVB/PDMS, 25 compounds were identified, including 2,5-dimethyl furan, 2-methyl-1-propanol, and 1,2,3-trimethyl benzene across the three culture systems. With the CAR/PDMS, 22 compounds were detected, among them three VOCs uniquely present during co-culture (ethyl tiglate, β -neoclovene, 1,3,4,5,6,7-hexahydro-2,5,5-trimethyl-2H-2,4a ethanonaphthalene). This fiber also revealed higher abundance of alcohols, aldehydes, esters, and sesquiterpenes. These findings support the potential of native Trichoderma strains as biocontrol agents against frosty pod rot and highlight BIF7-C1 as a promising candidate for further chemical and functional studies. • VOCs from strain BIF7-C1 showed the strongest inhibition of M. roreri. • nVOCs from strain BIF14-C2 showed the highest inhibition with viable M. roreri. • Findings support Trichoderma spp. as promising cacao biocontrol agents