Unexpected identification of Rychc PVY resistance in russet breeding clones

Wednesday, July 28, 2021
2:15 PM - 2:35 PM

Potato virus Y (PVY) is a devastating virus affecting potato production throughout the Americas and worldwide. Extreme resistance to PVY is conferred by three genes (Ryadg, Rysto, and Rychc) which have been introgressed into cultivated varieties. Ryadg and Rysto are used in breeding programs and are present in a few recently released varieties. However, Rychc is currently only present in non-russet varieties or newly introgressed material. Russeted varieties are the predominant type grown in the western United States where a majority of U.S. potatoes are grown. With the application of a multiplex test for all PVY resistance genes to existing germplasm, we have identified six high quality russet breeding clones containing Rychc. All of them show extreme resistance to PVY in field trials, despite their pedigrees containing no indication that they would be resistant to PVY. We have confirmed that the Rychc marker is linked to PVY resistance and postulate the existence of a second source of resistance in the same population which does not amplify any known PVY resistance markers. The existence of good russet breeding clones containing Rychc will be of great benefit to ongoing efforts to breed PVY resistance into russet varieties.
Breeding and Genetics