Modification of flower color in torenia (Torenia fournieri Lind.) by genetic transformation

Abstract

We modified flower color in torenia (Torenia fournieri Lind.) by transferring the chalcone synthase (CHS) or the dihydroflavonol-4-reductase (DFR) gene in sense or antisense orientation by Agrobacterium-mediated gene transfer. The modification patterns of flower color among the transformants formed three groups: (1) same color as the wild-type plant; (2) whole corolla changed to a uniformly light color; and (3) with greater degree of lightening in the tube than in the lip. Transformants incorporating antisense transgene(s) tended to become group 2 types, with no plants becoming group 3 type. Transformants harboring sense transgene(s) tended to become group 3 types, rather than group 2 types. Sense genes and antisense genes seemed to have different potential for changing the flower color. We also produced transformants with new characters in torenia flower color; for example, lines with pastel flowers, wavy patterned flowers and parti-colored flowers. We regard this system to be useful for flower color breeding in torenia and for studying gene expression.