We modified flower color in torenia(Torenia fournieriLind.) by transferring the chalcone synthase (CHS) or the dihy-droflavonol-4-reductase (DFR) gene in sense or antisense orientation byAgrobacterium-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. © 2000 Published by Elsevier Science Ireland Ltd. All rights reserved