Gene network underlying the response of harvested pepper to chilling stress

Cold storage is an effective postharvest control strategy to maintain the freshness of vegetables by suppressing respiration. However, subtropical plants including pepper (Capsicum annuum L.) undergo chilling injury. To better understand the molecular mechanisms involved in preventing chilling injury, transcriptome profiling analysis of peppers stored in a cold chamber and treated with 50μM methyl jasmonate (MeJA) and 1μLL^-1 1-methylcyclopropene as an ethylene reaction inhibitor was performed. A total of 240, 470, and 290 genes were upregulated and 184, 291, and 219 genes down-regulated in cold-, MeJA- and 1-methylcyclopropene-treated peppers, respectively. MeJA-treated peppers had significant transcriptome changes compared to cold- and 1-MCP-treated peppers after 24h of storage. MeJA treatment upregulated the genes for peroxidase and catalase related to stress responses, as well as the ethylene-responsive factor (ERF) family and MAP kinase involved in ethylene signaling factors in peppers. Functional analysis revealed that in comparison with wild type plants, ERF1-expressing plants showed a higher antioxidant capacity and enhanced expression levels of oxidative stress-related and jasmonic acid synthesis-related genes during chilling storage conditions. Additionally, ERFs and JA biosynthesis gene expression in peppers during long-term cold storage was upregulated by MeJA. Thus, MeJA enables peppers to respond to cold stress and ethylene signaling, and this could help to prevent chilling injury. Our results suggest that ethylene signaling and JA synthesis share the reactive oxygen species (ROS) scavenger-mediated stress adaption system during chilling stress in pepper. In addition, these findings provide a global insight into the genetic basis for preventing chilling injury in subtropical crops.