Effect of environmental, developmental and genetic factors on flavonoid and carotenoid profile of Vaccinium berries

Vaccinium berries contain high yields of antioxidant compounds, such as flavonoids and carotenoids, which are recognized to benefit human health. Therefore, commercial interest in cultivated and wild Vaccinium berries is increasing globally. Flavonoids and carotenoids are important secondary metabolites, the biosynthesis of which is regulated by interaction of the genetic background of the plant and the surrounding environment. In fruits the production of secondary metabolites has also a tight linkage with developmental processes. The present thesis is focused on developmental and environmental factors affecting the biosynthesis of carotenoids and flavonoids in berries of the genus Vaccinium. In bilberry altogether eight carotenoids were detected, with lutein and β-carotene being the most abundant compounds, accompanied by minor amounts of xanthophylls, such as antheraxanthin, neoxanthin, violaxanthin and zeaxanthin. During ripening the accumulation of carotenoids decreased. Simultaneously the expression of a carotenoid cleavage dioxygenase (VmCCD1) gene increased, indicating degradation of carotenoids during the fruit development. Simultaneously, flavonols and anthocyanins accumulated during the last stages of berry ripening. Environmental factors had a marked effect on the anthocyanin profile of ripe bilberries. Especially lower temperatures affected more on the accumulation of the delphinidin-based anthocyanidins than on the cyanidin-based ones. However, the spectral light composition also played a role, as an increased proportion in blue wavelengths increased the delphinidin-based anthocyanins at ripe stage. The effect of light quality on other phenolic compounds and carotenoid accumulation was less pronounced. The present results can be applied to cultivation of Vaccinium species in order to produce berries with high nutritional value.