Comprehensive transcriptome and metabolome analysis reveals regulatory network for lignin biosynthesis in chicory sprouting

Chicory is consumed worldwide and is an important commercial crop. However, excess lignin deposition may reduce its quality. The comprehension of the molecular mechanism underlying the biosynthesis of lignin in chicory is currently inadequate. To address this, an integrative analysis of the metabolome and transcriptome profiles was performed in chicory sprout at three different stages. A total of 706 metabolites were identified, with cinnamic acid, ferulic acid, coniferaldehyde, and sinapaldehyde enriched during the growth of chicory sprouts. This suggested that these four metabolites may affect the growth of chicory sprouts. Transcriptome analysis demonstrated that the expression of most of the differentially expressed genes (DEGs) involved in lignin biosynthesis was up-regulated during chicory growth. Importantly, the metabolite and gene expression profiles were closely correlated during sprout development, especially in association with lignin biosynthesis. The results will serve as a reference for lignin biosynthesis in chicory and may also assist biologists in improving chicory quality.