Effects of 1-Methylcyclopropene Treatment on the Quality and Malic Acid Metabolism of ‘Xiangjiao’ Plum under Low-Temperature Storage

Abstract

‘Xiangjiao’ plum (Prunus salicina Lindl.) is a stone fruit that is vulnerable to the chilling injury (CI) that is caused by low-temperature stress. The effects of 1-methylcyclopropene (1-MCP) and ethylene absorbent (EA) treatments on the fruit quality and malic acid metabolism of ‘Xiangjiao’ plum stored at 4 °C were compared in this study. Compared with the control check (CK) and EA treatment, fumigation with 1.0 mg·L−1 of 1-MCP for 24 h could more significantly maintain the sensory and physiological quality of the fruit, increase the activity of antioxidant enzymes, and prolong the storage time of plums. Furthermore, 1-MCP treatment can regulate the high expression of the tonoplast dicarboxylate transporter (tDT) and phosphoenolpyruvate carboxylase (PEPC) gene, regulate the high expression of the NAD-malate dehydrogenase (NAD-MDH) gene at the end of storage, and inhibit the expression of the NADP-malic enzyme (NADP-ME) gene. These changes resulted in increased NAD-MDH enzyme activity and decreased NADP-ME enzyme activity, which inhibited the degradation of malic acid that is caused by CI. As a result, 1-MCP can effectively maintain the storage quality of ‘Xiangjiao’ plum, reduce the loss of pleasant sour taste, and improve the edible flavor and commercial value of the fruit.