Molecular Markers of Genes for Extreme Resistance to Potato Virus Y in Solanum tuberosum L. Cultivars and Hybrids

Potato virus Y (PVY) is one of the most harmful viral pathogens that reduces the potato yield and quality. The number of contemporary cultivars resistant to a wide range of PVY strains is very limited, which justifies potato breeding in this direction. Molecular markers of the Ry genes are universal tools for identifying new sources of resistance in the existing biodiversity of potato genotypes. In the paper, molecular markers of the Ry genes—YES3-3A, YES3-3B, RYSC3, and Ry186—were used for screening foreign and Russian potato cultivars and hybrids from the collections of the Lorch Potato Research Institute and the Vavilov Institute of Plant Genetic Resources. Molecular screening and рedigree analysis revealed that Russian potato cultivars and hybrids, which are characterized by extreme resistance to PVY, were obtained on the basis of foreign cultivars Alwara, Arosa, Bison, Bobr, and Roko as well as backcrosses of Hungarian breeding—donors of the Ry_sto gene linked to cytoplasmic male sterility—and form 128/6—a donor of the Ry_adg gene derived from S. stoloniferum. The RYSC3 marker linked to Ry_adg was found in interspecies hybrids from the Vavilov Institute of Plant Genetic Resources 8-1-2004, 8-3-2004, 8-5-2004, 135-5-2005, and 135-3-2005, which have the same origin with the participation of the species S. okadae k-20921 Hawkes et Hjerting and S. chacoense k‑19759 Bitt. The Ry186 marker of the Ry_chc gene is rare. It is present in 5% of the potato genotypes. Molecular screening revealed potato samples with markers of the Ry genes, which are of particular interest for further breeding. Data on the presence of Ry gene markers in potato cultivars and hybrids serve as valuable information in the selection of initial forms for hybridization.