1a. Objectives (from AD-416):
Develop Potato Virus Y (PVY) and nematode resistance by 1) screening advanced breeding clones and released varieties with molecular markers for Potato Virus X (PVX) and Potato Cyst Nematode (PCN) (Globodera pallida); 2) bioassay characterization of resistant clones/varieties for PVX, PVY, and PCN; 3) make crosses from resistant parents.
1b. Approach (from AD-416):
Multiple entries from North America potato breeding programs will be screened for PVX and PCN resistance using molecular markers and bioassay data. Bioassays of putative PVX, PVY, and PCN resistant clones will be done at the USDA, Agriculture Research Service (ARS) in Aberdeen, Idaho for PVX and PVY, and at Moscow, University of Idaho for PCN resistance. Resistant clones/varieties will be used in a crossing block to generate a virus and nematode resistant population for further screenings/evaluation.
3. Progress Report:
Progress in this project is related to Objective 2 in the parent project which emphasizes developing marker-assisted selection protocols to accelerate breeding for resistant to recurrent and emerging pathogens and pests in the U.S. The summary of work outlined below involves using molecular markers to characterize a sub-population for resistance to two viruses and one cyst nematode. Potato cyst nematodes and viruses such as Potato Virus X (PVX) and Potato Virus Y (PVY) cause significant crop losses, and strategies using genetic resistance offer long term sustainable control. This project used molecular markers to assist in pyramiding PVY, PVX and potato pale cyst nematode resistant genes into a cross between advanced potato breeding clone OR00054-1 with Ryadg and Nb genes (for PVY and PVX resistance) and the potato cultivar GemStar Russet with Rx1, Nb and Gpa2 genes (for PVX and cyst nematode resistance). A population of 88 progenies from the cross was screened with molecular markers for these genes of interest. The Ryadg gene segregated in a 1:1 ratio confirming that resistance in OR00054-1 was conferred by a single copy of the gene. Segregation for the Nb gene most closely fit a 3:1 ratio confirming that both parents carry a single copy of this resistance gene. Segregation of the Rx1 and Gpa2 genes also most closely fit a 3:1 ratio, suggesting both parents also carried a single copy of each of these genes. Out of 88 progenies 20 clones (23%) showed the four resistant genes (Ryadg, Gpa2, PVX Nb and PVX Rx1) while 29 clones (33%) showed Ryadg and PVX Rx1 resistant genes. A subset of 42 clones was screened in the field for resistance to PVX and PVY. Of the tested clones, 21 had PVX markers present and 9 of those were resistant to PVX (0-4% PVX). For the clones PVY reaction, 23 had the PVY Ryadg marker present and 11 of them were resistant to PVY (0-7% PVY). Two breeding clones, OR09158-65 and OR09158-120 had both markers present and were resistant to PVX and PVY. All clones without markers for PVX and/or PVY were susceptible to the viruses.