Insertion of a Retrotransposon into a Flavonoid 3'-hydroxylase Homolog Confers the Red Root Character in the Radish (Raphanus sativus L. var. longipinnatus L. H. Bailey)

Flavonoid 3'-hydroxylase (F3'H) has an important role in determining anthocyanin patterns in plants. Here, we analyzed root coloration characteristics in the radish by investigating anthocyanidin and expression of F3'H genes in cultivars with purple, red, or white roots. Cyanidin was detected in the roots of the purple radish, while pelargonidin was found in the red radish; however, neither of these anthocyanidins was detected in white radish. We isolated the RsF3'H gene of the purple root radish and found that it showed a relatively higher level of expression compared to the RsF3'H of the red radish. Moreover, we identified a retrotransposon, gypsy-Ty3, in the first exon of the F3'H homolog in the red radish. These results suggested that the F3'H enzyme may determine cyanidin-based anthocyanin in the purple radish, and that the lack of F3'H function due to the retrotransposon insertion, contributed to pelargonidin-based anthocyanin accumulation in the red radish.