1-Methylcyclopropene promotes glucosinolate biosynthesis through BrWRKY12 mediated jasmonic acid biosynthesis in postharvest flowering Chinese cabbage

Flowering Chinese cabbage is a Brassica vegetable that is rich in glucosinolates with health-promoting effects. 1Methylcyclopropene (1-MCP) plays a pivotal role in procrastinating aging and maintaining the quality of postharvest vegetables and fruit products. However, understanding of the underlying molecular mechanisms of 1MCP involved in regulating glucosinolate biosynthesis is still limited and needs further studies. In present study, a total of eight glucosinolates were detected in flowering Chinese cabbage, containing five aliphatic, two indole, and one aromatic glucosinolates. 1-MCP could delay aging, enhance glucosinolate accumulation, and promote the transcripts of key glucosinolate biosynthesis genes (BrCYP79B2, BrCYP79F1, BrCYP83A2, BrCYP83B1, BrMYB28, and BrCYP83A1). Based on the transcriptome analyses, we noticed that BrWRKY12 was an interesting pivotal WRKY transcription factor and BrLOX4 was a key gene related to the jasmonic acid (JA) biosynthesis pathway involved in improving glucosinolate biosynthesis, which was mediated by 1-MCP. Furthermore, yeast one-hybrid, dual luciferase, and & beta;-glucuronidase tissue staining experiments also indicated that BrWRKY12 could directly bind to the BrLOX4 promoter region and activate its transcript. While silencing BrWRKY12 decreased JA content, down-regulated the transcripts of BrLOX4, BrCYP79B2, BrCYP79F1, BrCYP83A2, BrCYP83B1, BrMYB28, and BrCYP83A1, and reduced the glucosinolate accumulation. The results of this work advance our understanding of 1-MCP-enhanced bioactive components and initially confirmed that 1MCP promoted JA content through BrWRKY12-mediated JA biosynthesis, resulting in improving the glucosinolate accumulation in postharvest flowering Chinese cabbage.