The maize Lc regulatory gene up-regulates the flavonoid biosynthetic pathway of Petunia

Petunia (cv. Mitchell) transformants were produced which expressed the maize Leaf colour (Lc) cDNA under the control of the CaMV 35S promoter and had enhanced pigmentation in both vegetative and floral tissues. In flowering transgenic lines, intense pigmentation of leaves, stems and sepals occurred, along with lower levels of pigmentation in the flower tube and limb. No anthocyanins were detected in leaves, sepals and flower limb of wildtype Mitchell petunia. Of the 12 phenylpropanoid genes examined, transcript levels for nine flavonoid-specific biosynthetic genes were up-regulated in the transgenic Le lines, including weak activation of CHS, CHI and F3H along with stronger activation of DFR, F3'H, F3'5'H, ANS, UFGT and 3RT. PAL, C4H and FLS were unaffected by Lc. Lc-induced pigmentation in Mitchell petunia appears to be specific to the sub-epidermal layer in all tissues examined, including the flower limb. The results show that the monocot Le regulatory gene from maize can up-regulate the expression of both early and late flavonoid biosynthetic genes and enhance anthocyanin production in the dicot species Petunia.