Conversion of Abaxial to Adaxial Petal in a Torenia (Torenia fournieri Lind. ex Fourn.) Mutant Appeared in Selfed Progeny of the Mutable Line Flecked

We isolated a torenia mutant Begonia from selfed progeny of the mutable line Flecked, in which the ventral petal of the flower was converted into dorsal petal. In normal-type (NT) flowers, dorsal petals were pale violet and limbs of lateral and ventral petals were violet, whereas the ventral petal had a yellow nectar guide. In contrast, the ventral petal of mutant-type (MT) flowers changed to pale violet, and the nectar guide disappeared. These altered pigmentation patterns were observed from the early stage of corolla pigmentation. Expression analyses of the floral symmetry genes CYCLOIDEA (CYC), RADIALIS (RAD), and DIVARICATA (DIV) showed that TfCYC1, TfCYC2, TfCYC3, and TfRAD1 were mainly expressed in dorsal petals of NT flowers, but in the mutant, these genes were expressed in the ventral petal similar to dorsal ones. These results suggest that conversion of ventral to dorsal petal in the Begonia mutant is caused by high expression of TfCYC1, TfCYC2, TfCYC3, and TfRAD1 in the ventral petal, comparable to their expression in dorsal petals.