S19 - Session O5 - Bluer than blue: regulation of delphinidin branch anthocyanins in Vaccinium berries

Authors: Laura Jaakola *, Amos Samkumar, Katja Karppinen, Inger Martinussen

Vaccinium berries are recognized for the various health beneficial properties, which are generally linked to the high yields and the complex profile of flavonoids reported in these species. Flavonoid classes of anthocyanins, proanthocyanidins, and flavonols are generally found in all Vaccinium species. Anthocyanins are one of the main pigments in plants contributing to the characteristic reddish to blueish colours in flowers and fruits. So far, over 650 different natural anthocyanins have been identified, most important ones being glucosides of six common aglycons. Of these, delphinidin branch anthocyanins, namely delphinidins, petunidins, and malvinidins are responsible of blueish colours. In blue Vaccinium berries, including bilberry ( V. myrtillus ) and cultivated blueberries (e.g., V. corymbosum , V. angustifolium ), anthocyanin profile consists of cyanidins and petunidins in addition to delphinidin branch anthocyanins. The biosynthesis of anthocyanins is regulated via co-ordinated transcriptional control of the enzymes in the pathway by the interaction with the so-called MBW-complex including DNA binding R2R3 MYB transcription factors, MYC-like basic helix loop helix (bHLH) and WD40-repeat proteins. Flavanone 3'5' hydroxylase (F3'5'H) is the key enzyme for the branching point towards delphinidin branch. Some upstream molecular regulators of the pathway have been identified and in general the biosynthesis is controlled both at the developmental level as well as by the surrounding environmental factors. We have studied the regulation of anthocyanin biosynthesis in Vaccinium berries both in controlled and in field experiments. Our recent results have revealed new information on the key regulators controlling the different branches of the anthocyanin biosynthesis in blue-colored berries. Transcriptome analyses combined with metabolite results identified signaling routes leading to increase in delphinidin branch anthocyanins. Our results show that the anthocyanin composition in blue Vaccinium berries could be modified by specific environmental factors.