Phenological traits such as the timing of bud break and flowering are regulated by the activity of various genes within an intricate control network. Besides this polygenic nature, the strong impact of environmental cues complicates the study of these traits additionally. In the present work, quantitative trait loci (QTL) for time of bud break on the linkage groups 3, 4, 7 and for time of full bloom on the linkage groups 1, 4, 7, 8, 14, 17, 18 and 19 of a biparental grapevine cross population were identified. Additive effects of the flowering time QTLs could be demonstrated. The QTL on linkage group 14 has the greatest influence on flowering time and is regarded as the main QTL for this trait in the investigated cross population. By increasing the number of F1-individuals and creating an improved genetic map, the positions of the QTLs in the grapevine genome could be refined. So far, no genetic markers for marker assisted selection (MAS) of flowering time are available. The availability of such markers would allow the targeted breeding of later flowering varieties in the face of climate change leading to accelerated phenology. The transferability of SSR markers from the identified QTL regions to a set of genetically diverse grapevine varieties was examined. As a result, several SSR markers can be proposed, which show the potential to enable a counter selection of earlier flowering genotypes in breeding programs. The seasonal expression profiles of candidate genes within the QTL regions on linkage groups 7 and 14 were examined. They play potential roles (i) in the regulation of floral induction and inflorescence branching within the winter buds, (ii) in the initiation of bud break and the associated differentiation and correct morphological development of leaves, (iii) in inhibition of bud break by maintaining dormancy in winter and (iv) in single flower development after bud burst.weiterlesen