<i>Trichoderma</i> spp. volatile organic compounds protect grapevine plants by activating defense‐related processes against downy mildew

Volatile organic compounds (VOCs) are produced by soil-borne microorganisms and play crucial roles in fungal interactions with plants phytopathogens. Although VOCs have been characterized Trichoderma spp., the mechanisms against phytopathogens strongly differ according to strain pathosystem. This study aimed at characterizing three strains used as biofungicides investigate their effects grapevine downy mildew (caused Plasmopara viticola). A VOC-mediated reduction of severity was found leaf disks treated asperellum T34 (T34), T. harzianum T39 (T39), atroviride SC1 (SC1) 31 were detected head space-solid phase microextraction gas chromatography–mass spectrometry. Among annotated, α-farnesene, cadinene, 1,3-octadiene, 2-pentylfuran, 6-pentyl-2H-pyran-2-one reduced on disks. In particular, 2-pentylfuran increased accumulation callose enhanced modulation defense-related genes after P. viticola inoculation, indicating an induction defense mechanisms. Moreover, activated hypersensitive response possibly reinforce reaction. These results indicate that can induce resistance, these molecules could be further applied control mildew.