An antisense chalcone synthase cDNA leads to novel colour patterns in lisianthus (Eustoma grandiflorum) flowers

Three cultivars of lisianthus (Eustoma grandiflorum (Grise.)) were transformed with a homologous antisense CHS cDNA via Agrobacterium-mediated transformation. Over 50% of the transgenics derived from the purple flowering lines exhibited an altered flower colour pattern ranging from small streaks of white on the wild-type purple background through to completely white flowers. A significant portion of the transgenic lines showed unstable phenotypes. Northern and biochemical analysis showed that the altered flower patterns were associated with a loss of CHS gene transcript and a corresponding loss of CHS enzyme activity. In the white flowering line the level of total flavonoids was reduced to ca. 2.0% of the wild-type level. Some of the transgenic plants also exhibited alterations in flower form such as the formation of frilled petal tips and reduced flower opening. Several of the new patterned lines are being evaluated for stability and possible commercial release.