Hydrogen sulfide mediated methyl jasmonate -induced cold resistance in peach fruit

Methyl jasmonate (MeJA) is a crucial cellular regulator involved in various developmental processes and defense mechanisms against environmental stresses. Hydrogen sulfide (H2S), a novel gas transmitter, has been shown to play a significant role in stress mitigation in plants. While there is established crosstalk between these two signaling molecules in plants, the evidence of their interaction within fruit remains notably insufficient. In this study, we investigated whether H2S serves as a downstream signal for MeJA during the cold storage of peach fruit. Exogenous MeJA application reduced cold damage in peach fruit, as indicated by a notable decrease in the browning index (BI) and malondialdehyde (MDA) content. This mitigation was attributed to the downregulation of polyphenol oxidase (PPO) gene family transcription in peach, like PpPPO1, PpPPO2, and PpPPO8. Furthermore, endogenous H2S levels in MeJA-treated peaches increased during storage. We performed a genome-wide analysis on H2S biosynthesis genes, PpLCDs and PpDCDs, and assessed their expression levels in peaches. Among them, PpLCD1, PpLCD3, PpLCD5, PpDES1, PpDES3, and PpDES5 were identified as contributors to H2S biosynthesis in peaches. Additionally, PpLCD3, PpLCD5, PpDES1, PpDES2, and PpDES4 were observed to transiently respond to MeJA application. Several JA signaling-related cis-elements, including TGACG-motif, CGTCA-motif, G-box, and low-temperature responsive element, were found in the promoters of these LCD/DCD genes. In vitro experiments with exogenous H2S applications further confirmed the protective role of H2S in cold-stored peaches. Our findings suggest that H2S-mediated MeJA signaling alleviates chilling injury in peach fruit during low-temperature storage.