show Abstracthide AbstractVitis vinifera cv. Tannat is largely cultivated in Uruguay for the production of high quality red wines. Its most notable characteristic is an elevated content of polyphenolic compounds, which provide an intense purple color and remarkable antioxidant properties to the wine. To characterize the genetic components encoding this important phenotypic characteristic, the genome of the Uruguayan Tannat clone UY11 was sequenced to 134X coverage using the Illumina technology and assembled with a mixed approach of de novo assembly and iterative mapping on the PN40024 reference genome. An approach based on both reference-guided annotation and de novo transcript assembly of RNA-Seq data allowed the definition of 3,673 genes not previously annotated in PN40024 that we consider novel, and the discovery of 2,228 genes not shared with the grapevine reference genome that we consider private to Tannat. Expression analysis showed that private genes contributed substantially (more than 50%) to the overall expression of enzymes involved in phenol and polyphenol biosynthesis indicating that the dispensable portion of the grapevine genome contains many private genes which are likely to contribute to the peculiar phenotypic characteristics of this grapevine variety.