Résumé
In order to answer the new challenges faced by viticulture, the objective of grapevine breeding is to create new cultivars cumulating both resistance to pathogens and adaptation to climatic changes while still offering a high quality of the final products. These traits have to be accumulated from different sources, several Vitis species for resistance to biotic and abiotic stresses and V. vinifera for quality. The genetic bases of the variability of these complex traits are still poorly understood in grapevine compared to other crops, in particular because searching for QTLs in perennial woody species is very long, tedious and costly. Applying association genetics at the whole genome scale ("genome-scan" technique) will permit to more rapidly and more efficiently identify the main genetic factors underlying the variation of these agronomically important traits, by taking advantage of the high variability and large number of recombinations accumulated within the available genetic resources. Precise knowledge of the structure of genetic diversity and of linkage disequilibrium in analyzed samples is crucial to design and perform association genetics studies. DL-Vitis project proposes to produce this knowledge for several Vitis species of interest for breeding, V. vinifera, V. riparia, V. cinerea and V. aestivalis. Three main scientific objectives were proposed for this project : - to characterize the structure of genetic diversity within populations of the 3 wild Vitis species - to characterize linkage disequilibrium (using SNPs) in 4 genomic regions in 5 populations of V. vinifera and 1 population of each of 3 wild Vitis species - to test the genome -scan method for two important traits, resistance to downy mildew and berry size.