Integrative transcriptomics and metabolomics reveal the possible lignification mechanism of Lei bamboo shoots during ambient temperature storage

Abstract Lignification is a typical senescence characteristic of postharvest Lei bamboo (Phyllostachys violascens) shoots during storage, which greatly limits its edible value and shelf life. In this study, the underlying molecular mechanism of lignification in bamboo shoots during storage at 20±4 °C was elucidated using quality and physiochemical indices, as well as integrated transcriptomics and metabolomics analyses. The results revealed increased weight loss, browning, cellulose, and lignin contents of bamboo shoots during storage. Phenylalanine ammonia-lyase activity peaked at 3 d, while 4-coumarate coenzyme A ligase (4CL) and peroxidase (POD) activity increased continuously. Cinnamyl alcohol dehydrogenase activity reached its lowest point on day 3 but recovered to a level close to that of day 0 by day 6. Combined transcriptomics and metabolomics analyses identified seven lignification-related genes (PvC4H-1, Pv4CL-1, PvCAD-1, PvHCT-1, PvCCoAOMT-1, PvF5H-1, and PvF5H-2) and three metabolites (ferulic acid, (E)-ferulic acid, and p-coumaroyl quinic acid) that may be closely associated with lignin biosynthesis. We speculate that the lignin present in Lei bamboo shoots is mainly guaiacyl (G)-lignin and syringyl (S)-lignin. Our findings provide new insight into the lignification mechanism in postharvest bamboo shoots during storage at ambient temperature.