Chalcone 3- Hydroxylase: yellow colouration of flowers

Background Different yellow pigments can be responsible for the yellow colouration of flowers. This includes the wide-spread carotenoids, but also betalains, quinones, yellow flavonoids and anthochlore pigments (chalcones and aurones). Many popular ornamental plants do not produce yellow varieties or only ivory and pale yellow varieties despite of intensive conventional breeding efforts. World-wide, there are many attempts to use molecular breeding approaches for the creation of yellow varieties of such ornamental plants. Currently, two approaches are performed; one using aureusidine synthase (AUS) from snapdragon, the others chalcone reductase (CHR) present e.g. in soybean for the accumulation of stable 6’-deoxychalcones. However, there are no reports available on the creation of prototypes showing a satisfying yellow flower colour.