Mechanical Injury Enhances Ethylene-Associated Transcriptional and Metabolic Responses of Strawberry Fruit During Shelf-Life Period

Strawberry (Fragaria × ananassa) is a typical non-climacteric fruit in which the contribution of ethylene to postharvest ripening remains controversial. Mechanical injury can induce endogenous wound ethylene production, providing an opportunity to strengthen ethylene-associated responses when combined with exogenous ethylene exposure. In this study, ‘Benihoppe’ strawberry fruit were subjected to control (CK), mechanical injury (MI), ethylene treatment (ET), and combined mechanical injury and ethylene treatment (ME). Changes in postharvest quality, ethylene biosynthesis, oxidative damage, metabolomic profiles, and transcriptomic profiles were evaluated during the shelf-life period. ME-treated fruit showed the most severe postharvest deterioration, with accelerated softening, visual quality loss, and enhanced total anthocyanin accumulation. ME treatment was associated with the highest 1-aminocyclopropane-1-carboxylic acid (ACC) accumulation, which reached 5.9 nmol g−1 fresh weight (FW) at day 3 and remained at 4.2 nmol g−1 FW at day 6, indicating strengthened ethylene biosynthesis under combined treatment. ME fruit also showed the highest relative electrolyte leakage, malondialdehyde (MDA) content, and H2O2 accumulation, indicating more severe oxidative membrane damage. Multi-omics analyses revealed extensive metabolic and transcriptional reprogramming. Comparisons of CK vs. ME, MI vs. ME, and ET vs. ME identified 4012, 2825, and 7042 differentially expressed genes, indicating that ME induced a transcriptional state distinct from both untreated and single-treatment fruit at day 6. Differentially accumulated metabolites and differentially expressed genes were mainly associated with phenylpropanoid and anthocyanin biosynthesis, sugar-acid metabolism, oxidative stress, and hormone-related transcriptional regulation. Collectively, combined mechanical injury and ethylene exposure were associated with more rapid postharvest deterioration, aggravated oxidative membrane damage, and coordinated transcriptional and metabolic remodeling in strawberry fruit.