Efficient production of novel floral traits in torenia by collective transformation with chimeric repressors of arabidopsis transcription factors

Molecular breeding with genetic modification enables the production of novel floral traits in floricultural plants that could not be obtained by traditional breeding. To facilitate novel flower production, we collectively introduced 2 sets of 42 and 50 chimeric repressors of Arabidopsis transcription factors into Agrobacterium and then used these to co-transform torenia (Torenia fournieri). We generated 750 transgenic torenias, and identification of the transgenes revealed that more than 80% of the transgenic torenias had a single transgene. A total of 264 plants showed phenotypic modification, and 91.2% displayed modified flower colors and/or shapes, such as altered color patterns, curled petal margins, and wavy petals. These results indicated that the collective transformation system can be applied to molecular breeding of flowers. Detailed analysis of the phenotypes revealed that PETAL LOSS could control blotch sizes and that modification of cell shape could change the texture of petals. We found that the chimeric repressors of functionally unknown transcription factors also induced novel floral traits, and therefore, the transgenic torenias provide an understanding of the functions of transcription factors that could not be revealed by previous studies in Arabidopsis.