“…C4H and CHS, the other two upstream genes of flavonoid biosynthesis are well investigated as C4H is the key enzyme in the second step of phenylpropanoid pathway as it controls the synthesis of ρ-coumaric acid from trans-cinnamic acid [34], while CHS is known to encode the first committed enzyme in flavonoid biosynthesis. CHS has been used extensively as a model for identifying and studying elements controlling the expression of flavonoid biosynthetic genes [5].…”