Abstract

Pigment and phenolic compound accumulation in grapes are characteristic to the state of maturation of each fruit tissue (skin, pulp, and seeds). Among these compounds, anthocyanins participate in colouring of fruits, among many other functions, and tannins are involved in the pigmentation of seeds. In the wine industry, these two molecules are considered as quality parameters of wine colour and astringency. Two classes of genes are involved in their biosynthesis: structural genes, which codify for the structural enzymes of the phenylpropanoid pathway, and regulatory genes, for which at least three families of transcription factors have been identified in diverse species - Myb, bHLH, and WD proteins. So far, only Myb genes have been identified and characterized in grapes. By means of BLAST-N in the TIGR Vitis vinifera GENE INDEX, we found two sequences similar to WD genes: TC47485 (WDlike-1) and TC40216 (WDlike-2). Their coding regions were cloned and sequenced and RT-PCR, Northern blot, and quantitative PCR analysis were designed to evaluate WD expression in different organs of Vitis vinifera and stages of berry growth and ripening. We have observed that these genes are expressed throughout the plant organs, but are differentially expressed in leaves, flowers, and berries. Both WD like putative proteins posses high sequence homology to PhAN11 and AtTTG1, transcription factors involved in the control of epidermal cell fate identity, although they belong to different clades within the four WD-repeat family.