Plant Molecular Physiology Prof. Jochen Bogs

Plants synthesize a wide variety of flavonoid compounds with important functions in disease resistance, protection from UV radiation and colouration of flowers and fruits (Mol et al., 1998). Flavonoids are present in many fruits and plant products (wine, fruit juices and tea etc.) and contribute to their colour, taste and nutritional value. In grapevine, anthocyanins, proanthocyanidins (PAs, condensed tannins) and flavonols are the predominant flavonoids and play important roles in the quality and health benefits of wine. We have isolated and characterized several genes encoding enzymes involved in flavonoid synthesis in grapevine (Bogs et al., 2005 and 2006). In grapes, flavonoids accumulate at specific stages during berry development and the genes encoding enzymes specifically involved in synthesis of anthocyanins, flavonols and PAs are only expressed when the respective flavonoid accumulates. We have isolated several grapevine transcription factors (TFs) with gene expression patterns correlating with the accumulation of the respective flavonoid.

Complementation and promoter experiments have shown that the TFs MYBPA1 and MYBA specifically control PA and anthocyanin synthesis, respectively. We will further elucidate the regulation of the flavonoid pathway by other grapevine TFs of the MYB and bHLH family. Expression these TFs in grapevine hairy root cultures and microarray arrays and metabolite profiles of these cultures will lead to the identification of new grape specific genes which are controlled by the respective TF. This approach will lead to a better understanding of the flavonoid pathway in grapevine and the possibility to synthesis specific flavonoids in hairy roots.