BREEDING OF TRANSGENIC ORANGE PETUNIA-HYBRIDA VARIETIES

Flower colour is the major contributor to the total ornamental value of a flower The combination of biochemical knowledge and genetic engineering technology has resulted in the addition of a new colour to the existing colour range of Petunia hybrida. This has been achieved by expression of the maize dihydroflavonol-4-reductase (DFR) gene in a suitable petunia acceptor which leads to the accumulation of pelargonidin-derived pigments in flowers. The resulting flower colour, however, was a pale brick-red, which is commercially unattractive in petunia. Our objective was to produce a product suitable for commercialisation by introducing the DFR gene into our breeding material via normal sexual recombination. Although the initial transformant exhibited many negative characteristics, first analyses indicated that it was feasible to obtain material for creating commercial hybrids. Experimental hybrids based on F-4 lines were obtained with improved phenotypical expression of the orange flower colour in combination with a good general performance. In order to assess consumer-related characteristics, selected experimental hybrids were tested under field conditions. All transgenic plants had a normal appearance when compared to non-transgenic control plants. No linkage was observed between the transgenic trait and any negative characteristic. From these studies it can be concluded that through a combination of biochemistry, breeding and genetic engineering it is possible to generate unique flower colours in a cultivar with commercial potential.