Exogenous NaHS maintains storage quality of Prunus salicina ‘Wushan plum’ by regulating the antioxidant system, endogenous H2S, ethylene and NO metabolism

Abstract

Prunus salicina ‘Wushan plum’ is a climacteric fruit, which rapidly ripens under the action of ethylene after harvesting, resulting in quality deterioration that seriously restricts the sustainable development of the industry. In order to examine the potential role of sodium hydrosulfide (NaHS, the donor of exogenous H₂S) in slowing down the ripening and senescence process of plum fruit, the changes in storage quality, antioxidant capacity, endogenous signals and gene expression levels were evaluated during storage at 25 °C for twelve days. The results indicated that NaHS treatment delayed the coloration of plum fruit and maintained higher firmness, titratable acid content (TA) and marketable fruit rate. Treatment with NaHS increased the activities of catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR) and ascorbate peroxidase (APX); promoted the accumulation of total phenols (TP) and ascorbic acid (AsA), and inhibited the increase in reactive oxygen species (ROS), malondialdehyde (MDA) and lipoxygenase (LOX) activity, which in turn alleviated oxidative damage. H₂S treatment down-regulated the expression of PsACO1 and PsACS1 and inhibited the production of ethylene; up-regulated the expression of PsSiR, PsSAT, PsOASTL, and PsLCD, which in turn elevated the activities of sulfite reductase (SiR), serine acetyltransferase (SAT), O-acetylserine cleavage lyase (OASTL), and L-cysteine desulfurylase (LCD), and facilitated the accumulation of the endogenous H₂S content; up-regulated the expression of L-Arginine synthesis-related genes and PsNOA, which increased the content of L-Arginine as well as the activity of nitric oxide synthase (NOS) and facilitated the synthesis of nitric oxide (NO). The above results indicated that NaHS could improve the antioxidant system, endogenous H₂S, ethylene, and NO metabolism of plum, thus maintaining the storage quality of the fruit.