Abstract
In the Japanese morning glory, most of spontaneous mutations conferring characteristic flower pigmentation patterns are caused by insertions of En/Spm-related transposable elements, Tpn1 and its relatives, within the genes for anthocyanin biosynthesis. It is well known that transposable elements are susceptible to epigenetic gene regulation. The recessive flecked mutation causing flower variegations is due to an insertion of Tpn1 into the DFR-B gene. The mutant occasionally produces segregants showing stable white flowers, called white variants, in which methylated cytosines within the Tpn1 internal sequence are increased. A dominant mutation, Blizzard, appears to be caused by large rearrangements including a Tpn5 insertion within the DFR locus. The mutant blooms variegated flowers, suggesting that the expression of the DFR-B gene can change in active and inactive states without altering its genomic sequence. We will discuss the transposons involved in these epigenetic regulations of anthocyanin biosynthesis genes.
