Molecular markers as tools in breeding for resistance to Potato Virus Y

Potato virus Y (PVY) is an economically important pathogen of potato as a vegetatively propagated crop. High resistance to all strains of PVY is determined by Ry-genes, which are introgressed into modern potato varieties from a limited number of sources of resistance ‒ Solanum stoloniferum Schlechtd. et Bche., Solanum andigenum Juz. et Buk., Solanum chacoense Bitt. Use of new species Solanum and interspecific hybrids based on them provides for the expansion of existing potato gene pool in breeding for resistance to PVY. Traditional breeding for resistance to viruses has still a great potential, though, it is a long and laborious process. Molecular markers linked to Ry-genes are widely integrated in order to increase the effectiveness of practical breeding. Previous studies have revealed a number of shortcomings in using the molecular markers of Ry-genes. To assess the predictive abilities of molecular markers RYSC3, M45, M6 of the Ryadg gene and YES3-3A of the Rysto gene for resistance to PVY, the F1 generation of two potato populations was studied, in the creation of which inter-specific hybrids were used. The nature of segregation 5:3 obtained by phenotype showed that the original parental forms can be the sources of not only previously identified, but also unidentified Ry-genes and Ny-genes of hypersensitivity. Correlation coefficient between the presence of markers and resistance to PVY was 0.64 for the YES3-3 marker (79 % matching) and 0.54 for RYSC3, М45, М6 markers (76 % matching). There have been revealed the cases of “false positive” results of the study (the presence of a marker in susceptible genotypes), which indicate to the insufficient effectiveness of the markers used. The marker segregation observed in the populations was consistent with chromatid segregation, confirming the simplex nature of Ry-genes inheritance from resistant parents. The ratio of genotypes with the presence/absence of markers was 0.86:1.