1Department of Plant Production Technology, School of Agricultural Technology, King Mongkut’s Institute of Technology Ladkrabang (KMITL), Ladkrabang, Bangkok 10520, Thailand
2Research Institute of Modern Organic Agriculture, King Mongkut’s Institute of Technology Ladkrabang (KMITL), Ladkrabang, Bangkok 10520, Thailand
3Department of Biology, School of Science, King Mongkut’s Institute of Technology Ladkrabang (KMITL), Ladkrabang, Bangkok 10520, Thailand
Abstract
Phytophthora rot of durian var Monthong caused by Phytophthora palmivora has been proven to be a serious threat to durian plantations in Thailand. The research was targeted to isolate the causal pathogen and prove its pathogenicity by Koch’s postulate. Morphology and molecular phylogeny have confirmed the identification of pathogenic and antagonistic fungi. Evaluation of antagonistic fungus against plant pathogen in vitro and greenhouse conditions, morphology and molecular phylogenetic identification confirmed antagonistic species Trichoderma hamatum K01 and pathogenic isolate P. palmivora PYSC01. The crude metabolite of T. hamatum K01, namely TK01-MeOH gave the most substantial inhibitory effect to inhibit colony growth and sporangia formation at ED50 (50% effective dose) values of 288 and 118 µg/mL, respectively. Moreover, nanofibre namely nano-TK01M exhibited the best antifungal activity in inhibiting colony growth and sporangia formation at ED50 values of 11 and 3 µg/mL, respectively. Nano-TK01M treated on durian leaves induced the synthesis of scopoletin, which is known as a defense mechanism and marker of plant resistance or plant immunity. Moreover, the application of nano-TK01M significantly reduced disease incidence, the same as metalaxyl. Additionally, nano-TK01M treatment was the most effective in enhancing plant physiological parameters, including the synthesis of chlorophyll, carotenoid contents and promoted plant growth, compared to both metalaxyl and non-treated control. T. hamatum K01 produced antifungal metabolite pyrone 6-pentyl-2H-Pyran-2-one and sorbicillin. It is reported for the first time that pyrone and sorbicillin could be expressed as bioactive compounds in reduction of the disease incidence of durian rot caused by P. palmivora. The finding confirmed that nano-TK01M from T. hamatum K01 exhibited the most effective in controlling plant pathogen, which could be promoted as agricultural input for plant disease management, and it is also a nontoxic fungicide for living life and eco-friendly.
