Breeding of transgenic orange Petunia hybrida varieties

Summary

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 suitable material for creating commercial hybrids. Experimental hybrids based on F₄ lines were obtained with improved phenotypic 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 with 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 cultivars with commercial potential.