Evaluation of seedless grape cultivars by DNA markers linked to resistance loci

Seedless grapes are especially in demand by the consumer. Since table grapes are directly consumed for food, it is important that table cultivars have resistance to major pathogens and can be cultivated with minimal chemical treatments. Downy mildew (caused by Plasmopara viticola) and powdery mildew (Erysiphe necator) are among the most common seasonal diseases of grapevine in the world. The creation of resistant cultivars to these diseases is an important direction in grape breeding. Currently, many breeding programs of resistant cultivars are conducted using DNA markers. DNA markers are also used to study the gene pool, search for donors of valuable genes. We have studied a collection of seedless grape cultivars using DNA markers linked to downy mildew Rpv3, Rpv10, Rpv12 and powdery mildew Ren1, Ren3, Ren9 resistance loci. Fifty-eight seedless grape cultivars genotypes of various origins were analyzed, including newly created cultivars and ancient ones, also genotypes with unknown pedigree. For detection Rpv3 locus we used DNA-markers UDV305, UDV737; for identification Rpv10 locus – closely linked microsatellite marker GF 09-46, for Rpv12 – UDV343 and UDV360. DNA-marker analysis of R-loci to powdery mildew was performed: SС8-0071-014 and sc47-18 for Ren1, GF15-42 and ScORGF15-02 – Ren3 and CenGen6 – Ren9. As a control, we used the DNA of cultivars carrying resistance loci. Resistance loci (from 1 to 4 out of 6 analyzed) were identified in 20 among 58 genotypes according to DNA marker analysis. Only in 1 genotype Rpv10 was detected, Rpv3 was identified in 15 cultivars. Rpv3+Ren3+Ren9 were detected in three genotypes, and Rpv3+Ren3+Ren9+Rpv12 in one cultivar.