Investigation of VviLAZY1 and VviTAC1 for Optimizing the Vertical Growth and Branch Angle in Grapevine Varieties (Vitis vinifera)

One of the most important goals in agriculture is to increase biomass productivity and to reduce simultaneously space requirements of a plant. Optimizing the plant’s architecture could be a useful approach to facilitate this. Dardick et al. (2013) revealed with PpeTAC1 and PpeLAZY1 two genes in peach that greatly influence the branch angle and thereby the architecture of the whole plant. While PpeTAC1 promotes wide branching angles and horizontal growth, PpeLAZY1 stimulates the development of small branching angles and vertical growth. Genes homologous to TAC1 and LAZY1 are present in numerous families of the gymnosperms and angiosperms (Hollender et al., 2014). Investigating these genes opens up new possibilities to influence plant architecture and productivity by selective breeding. Vertical growth of the shoot is an important characteristic for the architecture of grapevines, as it facilitates pruning, a process, which is necessary, but represents a time-consuming and labor-intensive step in cultivation. We want to investigate the role of VviTAC1 and VviLAZY1 on the shoot attitude in Vitis vinifera. By sequence and expression analysis of VviTAC1 and VviLAZY1, it is our goal to identify characteristic sequence variations in a set of 13 reference grapevine varieties of Vitis vinifera, to develop diagnostic DNA-markers for different types of shoot growth: ‘erect’, ‘horizontal’ and ‘drooping’. In addition, we investigate the expression and the role of VviTAC1 and VviLAZY1 during plant development. Diagnostic DNA-markers will allow breeders to select for shoot attitude in early stages of plant development and to speed up breeding programs.