Biocontrol of Thielaviopsis paradoxa Causing Black Rot on Postharvest Snake Fruit by Volatile Organic Compounds of Trichoderma harzianum

The purpose of this study was to bioprospect the volatile organic compounds (VOCs) of various Trichoderma harzianum strains to control black rot of postharvest snake fruit, an important fruit commodity in Southeast Asia, caused by the fungus Thielaviopsis paradoxa. Trough an indirect confrontation assay, T. harzianum InaCC F88 was found as the most suppressing strain among others. The strain inhibited T. paradoxa with growth relative to control (GRC) of 71.14%. A volatolomic analysis using Headspace GC–MS of this strain showed the most abundant VOC was isoamyl alcohol (36.06%), followed by 2-methyl-1-propanol (21.92%) and 2-cyclopentenone (10.72%). Isoamyl alcohol as the major compound inhibited T. paradoxa with GRC of 71.44, 28.88, and 2.86% after the addition of 10, 20, and 30 µL of the vapor of pure compound, respectively. Moreover, in a 1.5-L close-container assay, the addition of 300 µL isoamyl alcohol vapor was also able to reduce lesion tissue in the pre-infected fruit up to 29.15% after 7 days of storage in room temperature compared to 58.97% in the absence of the pure compound. In conclusion, T. harzianum InaCC F88 through its VOCs was potential to biocontrol black rot in snake fruit, thus extend its storage time.