Figure 4. Putative flavonoids biosynthesis pathway.

(a) Proposed pathway for flavonoids biosynthesis. The numbers in brackets following each gene name indicate the number of unigenes annotated to that gene. Enzyme abbreviations: PAL, phenylalanine ammonia lyase; C4H, cinnamate 4-hydroxylase; 4CL, 4-coumarate CoA ligase; CHS, chalcone synthase; CHI, chalcone isomerase; F3H, flavanone 3-hydroxylase; FLS, flavonol synthase; DFR, dihydroflavonol 4-reductase; LAR, leucoanthocyanidin reductase; FNS, flavone synthase. (b) Expression levels of the candidate unigenes coding key enzyme involved in flavonoids biosynthesis pathways. Green and red colors are used to represent low-to-high expression levels, and color scales correspond to the mean centered log₂-transformed FPKM values.