Expansion of flower trait variations in interspecific hybrids between Torenia fournieri and Torenia baillonii

An increase in variations in flower color and shape is the key to success for floricultural crops. Cross combinations of Torenia fournieri having various flower colors and T. baillonii (B) having yellow petals could produce wider flower color variations in Torenia. Three different colored flowers of T. fournieri (violet, deep pink, and white) were crossed with B. The progenies had a chromosome number intermediate between the parents and showed narrow variation in petal color. They were male sterile but the ovule was partially functional. One of the interspecific hybrids was backcrossed with both parents. (T. fournieri violet (TFV)xB)xB produced much higher numbers of progenies with wider petal color variations than (TFVxB)xTFV. Investigation of the chromosome number of each progeny suggested that n=9 female gametes in (TFVxB) had higher potential to produce progeny than n=8 female gametes. Progenies of (TFVxB)xTFV showed poor petal color variation and its self-pollination produced progenies showing petal color variations without yellow. On the other hand, a cross combination of (TFVxB)xB and its self-pollination produced progenies showing a wide range of yellow base petal color variations. The present results show that backcrossing and self-pollination produce wider flower variations in Torenia interspecific hybrids. In the backcrossed progenies, plants having serrated petals appeared. The new characteristics were transmitted to progenies through further crossings.