Transcriptome-based Analysis Identifies the Key Biosynthetic Genes and Regulators Responsible for Lignification in Harvested Tsai Tai

Tsai Tai is one of the most important vegetables in the world. However, harvested Tsai Tai is prone to leaf yellowing and stem lignification, leading to apparent deterioration in quality and a decrease in value during storage. This study examines the effects of ethylene treatment on lignification in harvested Tsai Tai during storage. It was found that treatment with a low concentration (0.2 mM) of ethylene significantly promotes lignin accumulation in both the stems and leaves of harvested Tsai Tai, without affecting leaf yellowing. Ethylene exposure increased lignin levels, enhanced peroxidase (POD) activity, and stimulated hydrogen peroxide (H2O2) production. In contrast, treatments with 1-methylcyclopropene (1-MCP) and silver nitrate (AgNO3) inhibited lignin accumulation, reduced POD activity, and decreased H2O2 levels in harvested Tsai Tai during storage. Transcriptome profiling analysis of stems treated with a low concentration of ethylene and 1-MCP revealed that numerous genes were impacted by ethylene and 1-MCP during the storage of harvested Tsai Tai. Moreover, two POD genes (POD67 and POD71) were identified as key contributors to lignin biosynthesis and are regulated by transcription factors such as basic helix-loop-helix (bHLH), basic leucine zipper 1 (bZIP1), and bZIP2. The genes and transcription factors identified provide valuable targets for future breeding strategies aiming to control lignin biosynthesis. This could facilitate the development of new varieties with improved storage characteristics, particularly those associated with lignin content and quality. This research paves the way for advancing Tsai Tai breeding efforts and enhancing postharvest storage traits.