Validation and Implementation of Marker-Assisted Selection (MAS) for PVY Resistance (Ryadg gene) in a Tetraploid Potato Breeding Program

The gene Ryadg from S. tuberosum ssp. andigena provides extreme resistance to PVY. This gene has been genetically mapped to chromosome XI and linked PCR-based DNA markers have been identified. Advanced tetraploid russeted potato clones developed by the U.S. Pacific Northwest Potato Breeding (‘Tri-State’) Program with Ryadg PVY resistance were used in this study. The objective of this work was to assess the usefulness of molecular markers linked to Ryadg as a tool for selecting PVY resistance in a tetraploid potato breeding program. To achieve this, a full-sib tetraploid population segregating for Ryadg was screened with molecular markers linked to Ryadg, artificially inoculated with PVYO and evaluated in the greenhouse. A large percentage (96.4%) of the segregating lines showed coincidence between molecular markers and ELISA results at 40 days after inoculation. This justifies the use of molecular markers as an alternative to artificial inoculation followed by ELISA. Segregation (resistant vs. susceptible) based on ELISA and molecular marker results in the full-sib population indicated the presence of Ryadg as a simplex in the PVY resistant parent OR00030-1. Additional full-sib populations segregating for the Ryadg gene coming from OR00030-1 and from a related clone, AOR00628-3, were evaluated under field conditions. MAS can be used as a fast and efficient tool to select for PVY resistance, reducing the number of PVY susceptible lines retained for succeeding field evaluations, and thereby increasing the odds of generating PVY resistant potato varieties.