Trichoderma asperellum 2-X-3-3 as a sustainable biocontrol alternative to fungicides for postharvest pear diseases

Postharvest black spot disease caused by Alternaria alternata severely impacted pear storage and transportation, leading to substantial economic losses. Biological control, particularly with Trichoderma species, offers a sustainable and effective alternative to chemical fungicides. In this study, Trichoderma asperellum 2-X-3-3, isolated from greenhouse soil used for morel cultivation, exhibited strong antifungal activity against A. alternata, achieving a 74.4 % inhibition rate through producing volatile organic compounds (VOCs). These VOCs inhibited A. alternata by reducing conidial germination and sporulation, disrupting mycelial structures, and damaging cell membrane integrity. Moreover, they also improved pear quality, boosted antioxidant enzyme activity, and upregulated gene expression, significantly extending storage time. HS-GC-IMS analysis identified 15 VOCs, all of which exhibited antifungal activity against A. alternata. Among them, seven VOCs demonstrated significant inhibitory activity (>50 %), with three (3-octanone, acetic acid, and 1-hexanol) achieving nearly 100 % inhibition at 0.5 mL/L, highlighting their critical role in pathogen suppression. These findings demonstrate T. asperellum 2-X-3-3 as a potential, sustainable alternative to chemical fungicides for managing postharvest pear black spot disease, improving fruit quality, and extending shelf life.