1a. Objectives (from AD-416)
Objectives of this research are the development of potato varieties and germplasm with disease and pest resistances, reduced sugar accumulation, reduced need for production inputs, and enhanced nutritional qualities. Targets for resistance breeding are the major diseases and pests affecting potato production in the western United States. Many of these diseases and pests are nationally important, with germplasm and varieties from our program also benefitting potato producers outside the western United States as well. Objective 1: Develop potato germplasm with beneficial traits and make available to the potato industry, breeders, and geneticists. Objective 2: Develop enhanced potato varieties that benefit U.S. potato producers and consumers, including russets (fresh market and processing), long whites (processing), round whites (chipping), and specialty (red-skinned and yellow-fleshed), with emphasis on disease and pest resistance, reduced sugar accumulation, reduced need for production inputs, and enhanced nutritional qualities. Objective 3: Develop marker-assisted selection (MAS) protocols for potato traits, with an emphasis on pathogen and pest resistances. Objective 4: Characterize foliar and tuber responses of potato varieties to infection by newly identified strains of potato virus Y (PVY), and identify new sources of resistances to these PVY strains useful to potato breeders.
1b. Approach (from AD-416)
This research, performed under institutional biosafety policies, will benefit the western U.S. potato industry by developing new potato varieties that will maintain the economic viability and competitiveness of this region in an age of expanding global competition. This will be accomplished by producing new potato varieties with improved agronomic characteristics, nutritional qualities, disease/pest resistances, and a reduced need for production inputs such as water and nitrogen. Desired traits will be acquired from wild relatives of the cultivated potato and from germplasm of other potato breeding programs within and outside of the U.S. Identified parental material will be hybridized with potato breeding clones and varieties adapted to the irrigated environments of the western U.S. Progeny of hybridizations will be evaluated, performance data collected, and superior individuals selected and advanced in the program for release as potato varieties with enhanced attributes. Newer technologies, such as marker-assisted selection, will be used to facilitate the development of enhanced potato varieties. Replacing 5366-21000-023-00D 01/2008
3. Progress Report
Project 5366-21000-026-00D, “Development of potato varieties and germplasm with improved resistances, production efficiencies, and tuber qualities for the western U.S.” Progress in research included fine-mapping of potato leafroll virus (PLRV) resistance from the potato wild species, Solanum etuberosum. Resistance to this primary virus pathogen of potato is highly heritable across three generations of backcrossing to cultivated potato. Resistance was previously localized to chromosome 4, with a molecular marker identified that could be used for identifying resistant individuals to speed the development of PLRV resistant potato varieties. Markers even more closely linked to PLRV resistance than the one identified were not found due to chromosome rearrangements within chromosomes of S. etuberosum. A manuscript has been prepared detailing this research and is currently in review. Additional research on the evaluation of project germplasm for the presence of a potato virus Y (PVY) resistance gene (Ryadg) from Solanum tuberosum subsp. andigena also was completed. Research involved an assessment of PVY resistant breeding lines for the presence of three molecular markers linked to Ryadg and confirmation that their presence in a clone also was associated with resistance to multiple strains of PVY, including necrotic types. These necrotic strains can reduce tuber quality by producing necrotic ringspots in tubers. Results showed that the presence of the three molecular markers was correlated with high levels of PVY resistance. A manuscript detailing the research is currently in preparation. Use of the PLRV and PVY molecular markers in the breeding program has the potential to decrease the amount of time necessary to identify virus resistance in parents and progeny and therefore increase selection efficiency in the program. This research contributes to the National Program 301 Action Plan by addressing Component 3, Problem Statement 3A: Genetic Theory and Methods of Crop Improvement, and Problem Statement 3B: Capitalizing on Untapped Genetic Diversity. Progress also was made in characterizing foliar and tuber responses of North American potato varieties and Aberdeen advanced breeding clones to infection by newly identified strains of PVY, and for the identification of new resistances to these PVY strains. PVY isolates collected from a three year national PVY survey were used for the evaluations. Russet Burbank, the most widely grown potato cultivar in the U.S., showed no tuber symptoms when challenged with the PVY strains. Another cultivar, Ranger Russet, displayed minimal tubers symptoms from a small number of the isolates tested. This information is being disseminated at grower meetings, professional meetings, and will soon be incorporated into a peer-reviewed journal article. In addition, work was started with a collaborator from a virus research lab to determine the quantity of virus over time in PVY resistant cultivars using real-time PCR techniques. This research contributes to Component 3, Problem Statement 3B of the National Program 303 Action Plan: Disease Resistance in New Germplasm and Varieties.
1. Confirmation that potato virus Y resistance in potato breeding clones is conferred by the gene, Ryadg. New strains of potato virus Y have become increasingly problematic for the U.S. potato industry, resulting in rejection of seed by certifying agencies and an increasing incidence of tuber necrosis in commercial production. Molecular markers previously published as being linked to the PVY resistance gene, Ryadg, were used by ARS scientists in the Small Grain and Potato Germplasm Research Unit in Aberdeen, ID to assay PVY resistant germplasm in our breeding program. The presence of the markers was correlated with PVY resistance. Use of these markers in the breeding program has the potential to decrease the amount of time necessary to identify PVY resistance in parents and progeny and therefore speed the development of PVY resistant potato varieties. Np 303, Component 3, Problem statement B. This accomplishment contributes to Component 3, Problem Statement 3A of the National Program 301 Action Plan: Genetic Theory and Methods of Crop Improvement.
5. Significant Activities that Support Special Target Populations
Srinivasan, R., Alvarez, J., Bosque-Perez, N.A., Eigenbrode, S.D., Novy, R.G. 2008. Effect of an alternate weed host, hairy nightshade, solanum sarrachoides (sendtner), on the biology of the two most important potato leafroll virus (luteoviridae: polerovirus) vectors. myzus persicae (sulzer) and macrosiphum. Environmental Entomology. 37 (2):592-600