Dual Action of Ivy and Strawberry Essential Oils: Induction of MdPR10 Gene Expression and Antimicrobial Effects in Apple Fruits

One significant trend in the research of plant treatment methods is that regarding the use of natural-based methods in plant protection. In this study, antimicrobial activity and changes in <i>MdPR10</i> gene expression were tested for a total of five plant pathogens in a model of apple fruits, where strawberry and ivy EOs were used. The vapor-phase chemical composition of both EOs was profiled using HS-GC-MS. qRT-PCR was applied for a bacterial response analysis, together with disk diffusion assays, and minimum inhibitory concentrations were determined. To elucidate the molecular basis of the antibacterial potential of essential oils (EOs), docking analyses were performed. For <i>Xanthomonas arboricola</i> and <i>Pectobacterium carotovorum</i>, the presence of EOs resulted in the downregulation of <i>MdPR10</i>. Strawberry EO was more effective against weakly virulent strains of bacteria; ivy EO had greater inhibitory effects. HS-GC-MS detected 13 volatiles in strawberry EO-dominated by ethyl butyrate, ethyl 2-methylbutanoate, ethyl hexanoate, and ethyl 3-methylbutanoate-and 16 in ivy EO, characterized by monoterpenes and monoterpenoids with 1,8-cineole as the principal component. <i>P</i>-cymene showed the most potent binding activity against D-alanine-D-alanine ligase. Ivy EO has the potential to be effective as a natural preservative alternative mainly in postharvest technology.