Melatonin Reduces Lignin Biosynthesis by Fostering Epigenetic Modifications in Water Bamboo Shoots under Cold Storage

Chilling injury and lignin deposition reduce the market value of water bamboo shoots (Zizania latifolia) during cold storage. Melatonin (MT) application has been found to be effective in mitigating chilling injury in cold-stored vegetables and fruits. Thus, considering the importance of chilling stress in water bamboo shoots, we have examined the impact of exogenous MT application under cold storage. It was found that exogenous MT increased the expression of ZlCDPK12 and decreased the expression of genes in the phenylpropanoid pathway, including ZlPOD16, ZlC4H, ZlPAL1, ZlCAD2, and ZlCCR1. It delayed skin browning and softening, reduced weight loss, and maintained total phenol and flavonoid contents while reducing lignin deposition. Moreover, the transcript abundance of phenylpropane metabolism-related transcription factors ZlERF4, ZlbHLH49, and ZlMYC2.2 is correlated with promoter DNA methylation. Overall, our study provides insights into how exogenous MT treatment effectively inhibits the deterioration of water bamboo shoots during cold storage. Furthermore, the integration of transcriptome and DNA methylation data lays a foundation for future improvements through genetic engineering.