Genetics of berry colour and anthocyanin content variation in grapevine (Vitis vinifera L.subsp. vinifera)

Dissertation presented in fulfillment of the requirements for the Degree of Doctor of Philosophy in Biology (Molecular Genetics) at the Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa

Anthocyanin content of grape berry skin determines the colour of grapes and wine. This trait has been widely studied due to its importance for grape and wine marketing and also due to the antioxidant properties of anthocyanins. In this thesis the variation of this trait was investigated within and between cultivars. DNA sequence variation and differential gene expression were studied among clones of the cultivars Aragonez and Negra Mole. Grape colour phenotyping was explored using different phenotyping approaches. Association mapping was performed for a sample of 149 cultivars and association mapping methodologies considering structure and relatedness in the sample were discussed. It was observed that no DNA sequence variation was present in the studied genomic regions between different clones of the same cultivar. Differential expression between Aragonez clones with contrasting values of skin total anthocyanin concentration was found to be very subtle not showing any significant results after correction for multiple testing and with two fold-change. However, relaxing statistical stringency and focusing on functional groups of interest (flavonoid metabolism and transcription factors) a list of 24 genes of interest was identified. This included two genes involved in the flavonoid metabolism, coding enzymes related with the glucosylation of flavonoids and transcription factors of the following families: Myb, Myc, zinc fingers, WRKY, DOF, GRAS, homeobox domain, YABBY, basic-leucine zipper, pathogenesisrelated and plant homeodomain finger.(...)

Financial support from Fundação para a Ciência e a Tecnologia, grant number SFRH / BD / 29379 / 2006 and ERA-PG 074B GRASP GRAPE WINE.