Pyramidizing resistance genes in grape: a breeding program for the selection of elite cultivars
Grape is one of the most important fruit crops cultivated worldwide both for fresh consumption and wine production. All cultivars of Vitis vinifera are susceptible to several pathogens. Downy mildew (Plasmopara viticola) is one of the most dangerous diseases, causing heavy defoliation and crop losses. In the southern Mediterranean countries, powdery mildew (Uncinula necator) is also of major concern. Grape cultivation accounts for a large part of the fungicides sprayed in Europe. An alternative would be to use grape cultivars resistant to pathogens. Here, we present a breeding program, developed at the University of Udine, that aims to pyramidize genes involved in the resistance to powdery and downy mildew into a high-quality genetic vinifera background for the selection of new wine and table grape cultivars. Almost 6000 seedlings resulting from 71 different crosses done during 2010-2013 were grown. The parents were selected from a panel of elite wine or table cultivars and resistant genotypes. Offspring with pyramidized genes were obtained from 64 of the initial crosses. Natural infections were recorded during the first year of field growth. Seedlings (820) were also genotyped using molecular markers linked to four recognized resistance genes to downy mildew (Rpv1, Rpv3, Rpv10, Rpv12) and four resistance genes to powdery mildew (Run1, Ren1, Ren3, Ren4). After phenotypic and genotypic selection, 1128 progenies were grafted onto 'SO4' rootstock and grown in the open field. The following traits were observed for at least 2 years of production: berry color, type of cluster (loose vs. compact), production (high, medium, low), vegetative habit (weak vs. vigorous), and susceptibility to diseases other than powdery and downy mildews (mainly Botrytis cinerea and black rot). A general overview of genotypes with pyramidized resistance is presented.
Foria, S., Monte, C., Testolin, R., Di Gaspero, G. and Cipriani, G. (2019). Pyramidizing resistance genes in grape: a breeding program for the selection of elite cultivars. Acta Hortic. 1248, 549-554
candidate genes, marker assisted selection, Vitis vinifera, powdery mildew, downy mildew