Abstract
In the past decade, a considerable amount of grapevine research has focused on the identification of quantitative trait loci (QTLs) for disease resistance. Downy and powdery mildew resistances were the most studied traits with the discovery of 14 major effect QTLs for Plasmopara viticola (Rpv) and eight QTLs for Erysiphe (Uncinola) necator (Run and Ren), which are related to some extent in their responses against fungal pathogens. Besides the mildews, several resistance loci were mapped for phylloxera (Rdv1), Pierce's disease (Pdr1), black rot (Rgb1), crown gall (Rcg1) and nematodes (Xir1) transferring GFLV (grapevine fanleaf virus). For most of these resistance traits, associated molecular markers were identified and validated, so they can be considered a valuable tool for marker-assisted selection. Using grape accessions available in Northern Italian germplasm collections (Laimburg Research Centre, InnoVitis, Fondazione E. Mach), as well as breeding populations, we applied DNA marker analysis to verify the presence of multiple disease resistance traits. This provides evidence of the breeding potential for each accession/seedling with particular interest to genotypes with pyramided resistances, which may be employed in multi-disease resistance breeding.