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In this study, the mechanism by which the exogenous application of 150 nM signaling bioactive peptide phytosulfokine α (PSKα) delays senescence and improves antioxidant nutrient accumulation in strawberry fruit during storage at 4 °C for 18 d was investigated. Results showed that the higher endogenous accumulation of PSKα in strawberry fruit treated with 150 nM PSKα may result from the higher expression of PSK3 and PSK6 genes. Besides, the higher endogenous accumulation of Ca2+ in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher cytosolic accumulation of cGMP, resulting from the triggering of endogenous PSKα signaling pathway, represented by higher expression of PSKR1 gene. Besides, the higher endogenous melatonin accumulation resulting from higher expression of TDC, T5H, SNAT, and ASMT genes in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher endogenous accumulation of Ca2+. Moreover, the higher ABTS and DPPH scavenging capacity in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher accumulation of phenols, flavonoids, and anthocyanins, resulting from higher gene expression and activities of PAL and CHS. Based on our findings, the exogenous application of PSKα could be employed as a beneficial procedure for delaying senescence and improving antioxidant nutrient accumulation in strawberry fruit during cold storage, by triggering endogenous PSKα signaling, promoting endogenous melatonin accumulation, and activating the phenylpropanoid pathway.

Pomegranates were treated by dipping with acetyl salicylic acid (ASA) at three concentrations (0.1, 0.5 and 1.0 mM) immediately after harvest and then stored under chilling temperature for 14, 28, 42, 56, 70 and 84 days at 2 °C plus a subsequent period of 4 days at 20 °C. Control fruit exhibited more chilling injury (CI) symptoms (manifested by pitting and browning) than treated fruit during storage, accompanied by increased softening, ion leakage and respiration rate. The ASA treatments were also effective in maintaining higher contents of nutritive (sugars and organic acids) and bioactive compounds (total phenolics and anthocyanins) and total antioxidant activity (TAA), in both hydrophilic (H-TAA) and lipophilic (L-TAA) fractions. These results suggest that ASA could have potential postharvest application for reducing CI, maintain quality and improve the health benefits of pomegranate fruit consumption by increasing the antioxidant capacity.

Pomegranate fruit were treated with salicylic acid (SA) at different concentrations (0.7, 1.4 or 2.0 mM), then stored at 2 °C for 3 months to investigate chilling injury (CI). SA treatments, especially at 2 mM concentration, were highly effective in reducing CI and electrolyte leakage in the husk of pomegranate, as well as ascorbic acid (AA) loss compared with that observed in control fruit.