Antisense flavonol synthase alters copigmentation and flower color in lisianthus

In order to generate new flower colors in lisianthus, a flavonol synthase (FLS) coding sequence was isolated from lisianthus (Eustoma grandiflorum Grise.) using a petunia homologue (pCGP481) as a probe. The endogenous FLS mRNA transcript occurs early in petal development, concomitant with accumulation of flavonols in bud tissue, and ceases at onset of anthocyanin pigment production. Southern DNA analysis indicated FLS as a member of a multigene family in lisianthus. Transgenic plants of a purple flowered lisianthus line expressing antisense FLS under the control of the CaMV35S promoter produced flowers more red in color (magenta) than the original untransformed plant. The transgenic plants also showed novel red pigmentation (cyanidin) in early stage buds as well as deeply colored pistils, and accumulated dihydroflavonols at the expense of flavonols. Further, analysis of the progeny of crosses between the primary transformants and a deeply pigmented purple variety (Wakamurasagi) showed this novel phenotype to be stably inherited. Field trial assessment of antisense FLS plants indicated variation in the petal and early bud phenotype although variation in the transgenic flower color was within the range normally seen in commercial cultivars grown under commercial conditions.