Breeding strategy for the introgression of disease resistance genes into European grapevine

A breeding program aiming to introgress genes of resistance to several diseases, such as downy mildew, powdery mildew and Botrytis into the European grapevine has been initiated in 1998 at the University of Udine. Susceptible (S) and resistant (R) grapevine breeding lines were crossed according to a mating plan designed to produce S x R and R x R families. The R-lines included genotypes carrying resistances from American and/or Asian species. For each class of cross, several genotypes were crossed in all combinations irrespective of the way and without reciprocals. Selfing of S- and R-lines was also included. Twenty-eight crosses have already been made, the family size ranging from a few to 136 individuals. At the same time, molecular markers (anonymous SSRs and SNPs derived from Resistance Gene Analogs) were isolated to produce a transportable and functional linkage map. Beside 371 SSRs isolated together with other partners of the Vitis Microsatellite Consortium, further 101 new SSRs from AC-repeat enriched libraries were isolated. New libraries enriched in di- and tri-nucleotide repeats have been produced and isolation of new SSRs is underway. SNPs are being produced from 80 RGAs isolated in grape up to now. Through recurrent cycles of assessment of classes of phenotypic resistance/susceptibility and QTL analysis, we expect to elucidate the genetic control of resistance to several diseases and to identify genes/QTLs, which control such diseases. In the present paper, we give an overview of the whole research plan, the activities carried out, the results achieved in the first three years, and the strategy adopted to develop new grapevine cultivars suitable for the Friuli-Venezia Giulia region