Phenylalanine application enhances resistance metabolite accumulation and antioxidant capacity to alleviate chilling injury in postharvest nectarines

Peach fruit soften rapidly after picking, and cold storage is a common approach to extend the shelf life of peaches, but long-term low temperature storage is prone to cause chilling injury. In this study, phenylalanine (Phe) application effectively alleviated chilling injury in nectarine fruit, metabolome and transcriptome analyses revealed that multiple resistance pathways were induced by Phe treatment. Phe regulated primary and secondary metabolism, and the expression of several sugar metabolism genes was elevated following Phe treatment. The increased total flavonoids and total carotenoids contents in Phe-treated fruit maintained fruit nutrition and helped improve the free radical scavenging capacity. Phe treatment enhanced the activity of several antioxidant enzymes, including catalase, peroxidase, and superoxide dismutase, while reducing malondialdehyde content. Additionally, Phe inhibited the activity of pectate lyase, polygalacturonase, and β-galactosidase enzymes, thereby preventing the degradation of protopectin and delaying fruit softening during cold storage. Many phytohormone signaling genes were regulated in Phe-treated fruit, and Phe treatment primarily affected abscisic acid signaling. Moreover, several transcription factors and functional genes were identified as key factors in alleviating chilling injury caused by Phe application. This study comprehensively revealed the beneficial effects of phenylalanine on the cold resistance of nectarines during low temperature storage. • Phe application alleviated chilling injury in postharvest nectarines. • Phe inhibited pectin degradation and delayed fruit softening during cold storage. • Phe enhanced ABA signaling in nectarines under low-temperature.