Antifungal activity and mechanism of <i>Mentha spicata</i> essential oil and the major compounds on <i>Botryosphaeria dothidea</i> and their potential application to postharvest quality of <i>Actinidia chinensis</i> fruit

Botryosphaeria dothidea is an important pathogenic fungus, which poses serious threats to crops and causes substantial economic losses. Plant essential oils (EOs) have strong antifungal activity and induce fruit resistance to microorganisms. The antifungal activity and mechanism of Mentha spicata EOs and major compounds against B. dothidea, and the extending shelf life of Actinidia chinensis fruit were investigated. The results showed that estragole was a most abundant in M. spicata EO compounds. Mentha spicata EOs, D-carvone, estragole, and fenchone exhibited strong inhibitory effects on B. dothidea. Mentha spicata EOs and fenchone had significantly increased the electrical conductivity of B. dothidea solution and caused a loss of nucleic acid and soluble protein. Mentha spicata EOs and estragole suppressed the cellulase and peroxidase of B. dothidea; however, fenchone promoted the xylanase activity. Botryosphaeria dothidea proliferation on A. chinensis fruit was inhibited by M. spicata EOs and major compounds during days 3 to 7 in situ. Mentha spicata EOs and fenchone promoted the A. chinensis fruit cellulase activity; however, the xylanase activity was significantly reduced. The peroxidase activity of A. chinensis fruit was increased by estragole. This study showed that M. spicata EOs has great potential as antifungal agent used for fruit postharvest.