Plant Biotechnology 23, 25–31 (2006)

To produce white-flowered gentian plants, we attempted to suppress the chalcone synthase (chs) gene by Agrobacterium-mediated transformation. A binary vector, pSMABcCHS, harboring antisense cDNA of chs isolated from the gentian Gentiana triflora cv. Maciry under control of the CaMV35S promoter was transformed into an interspecific hybrid gentian (cv. Albireo; G. scabra G. triflora). The vector also contained the bar gene as a selectable marker. Three out of seventeen transgenic plants showed completely white flowers with 10 to 25% reduced anthocyanin content compared with the wild-type. Molecular analyses confirmed integration of the foreign genes and suppression of chs mRNA accumulation in their petals. Application of commercial herbicide including bialaphos showed that the transformants were strongly resistant. Segregation of the white-flowered and herbicide-resistant traits was tested using a T1 progeny obtained from crossing with a blue-flowered parental line. The results clearly showed that these two traits are inherited dominantly as linked traits in the T1 progeny, suggesting that these transgenic plants are useful resources for production of white-flowered gentians. These results also demonstrated for the first time the inheritance of foreign genes and genetic modification of flower color in transgenic gentian plants.