1a. Objectives (from AD-416)
Improve levels of disease resistance to foliar and soil-borne pathogens in potatoes. Improve processing and nutritional quality in potatoes through breeding and selection of superior germplasm. Evaluate advanced selections through replicated field trials prior to naming and release to stakeholders.
1b. Approach (from AD-416)
Use recurrent selection to improve diploid populations for disease resistances and processing quality. Use parental line breeding to improve tetraploid populations for disease resistances, processing quality, nutritional quality. Transfer these traits from improved diploids to the tetraploid level via 4x-2x crosses. Develop markers to facilitate introgression of desirable genes or deletion of undesirable genes from related species into commercial germplasm.
3. Progress Report
Research was conducted under National Program 301 (Plant Genetic Resources, Genomics and Genetic Improvement), Action Component 3 (Genetic Improvement of Crops). Objective 1: Increase Levels of Disease Resistance to Foliar and Soil-borne Pathogens in Potatoes Remnant seed were planted to fully constitute the third cycle late blight resistant diploid population after poor tuberization last year. Seed from the other families was increased. Tetraploid x diploid seedling tubers between commercial germplasm and late blight resistant diploid species were planted in an increase plot in the field in Maine. Tetraploid x diploid crosses were made between commercial quality germplasm and either late blight or early blight resistant diploids from their respective second cycle populations. Over 150 varieties were evaluated for resistance to Fusarium dry rot and 16 were found to be highly resistant. The experiment will be repeated next year. Began experiment to examine segregation for resistance to common scab in two families. Objective 2: Improve Processing and Nutritional Quality in Potatoes Through Breeding and Selection of Superior Germplasm. True seed were planted to produce seedling tubers to start the fourth cycle diploid high specific gravity population. Preliminary fertilizer studies were initiated to determine the effect of varying manganese levels on the expression of internal heat necrosis, and the effect of varying potassium levels on chipping ability in wild species hybrids. Tetraploid x diploid yellow-fleshed clones from three families were characterized for carotenoid profiles and quantities. These were replanted in 2008 in a replicated study to determine the inheritance of high carotenoid content. Objective 3: Evaluate advanced selections through replicated field trials prior to naming and release to stakeholders. Ninety-one round white breeding selections and four standard varieties were evaluated for fresh market and chipping potential. Thirty breeding selections (red-, purple-, white- skinned with red-, pink-, purple- or yellow-flesh) and three standard varieties were evaluated for their specialty market potential. In addition, six diploid breeding selections were evaluated for niche markets. One clone, B1992-106, a from-the-field chipping selection for the mid-Atlantic states, was put into tissue culture to generate seed for small-scale grower trials. University and industry cooperators were able to select and request tubers from among 58 clones remaining after six plus years of evaluation, 13 clones remaining after five years of evaluation, 52 clones remaining after four years of evaluation, and 355 clones remaining after one year of evaluation.
1. Early Generation Study for Developing Potatoes for the Eastern States. Potato varieties for different environments are needed. The ARS Potato Breeding Program works cooperatively with states along the entire length of the eastern seaboard. Normally, the first three years of selection are conducted in Maine by the ARS breeder, and then state scientists have a chance to make selections from this material (based on performance in Maine) for evaluation at their locations. At this point, though, less than 1% of the original population is typically left in the program. Three hundred fifty five second-year clones were produced in 2007 and cooperators from FL, SC, NC, NJ, PA, NY, and ME evaluated all 355 clones at their respective locations in 2008 and made selections based on their performance at their respective locations. Many of the clones selected at other locations would not have been available for selection under ‘normal’ procedures. In trying to develop potato varieties for different environments, breeding material needs to be made available much earlier in the breeding program to these different environments. This research is expected to result in new potato varieties for different environments. This research is under National Program 301, Component 3, Problem Statement 3C: Germplasm Enhancement/Release of Improved Genetic Resources and Varieties.
2. Micronutrient Status of Potatoes. Increasing micronutrients in potatoes could improve the human diet. Data on the mineral content of tubers from western and eastern potato producing regions was analyzed. These data revealed that there was significant variation in mineral composition (calcium, copper, iron, magnesium, manganese, potassium, phosphorus, sulfur, and zinc) in potato germplasm. Heritability estimates suggest that it will be possible to improve mineral composition through breeding. Although micronutrient deficiency is a serious problem in many parts of the world, some portions of the U.S. population also suffer from micronutrient deficiencies. This research indicates that potatoes can be developed with improved micronutrient content and this may be an effective way to improve human diets. This research is under National Program 301, Component 3, Problem Statement 3C: Germplasm Enhancement/Release of Improved Genetic Resources and Varieties.
5. Significant Activities that Support Special Target Populations