2007 Annual Report 1a.Objectives (from AD-416) Further identify and quantitate water-soluble compounds in skins of white-fleshed varieties and novel compounds in wild species. Examine whether certain post-harvest treatments increase phytonutrient content. Examine the effects of different levels of nitrogen fertilization on phytonutrient content. Identify potato germplasm with resistance to potato tuber moth, powdery scab, root-knot nematode, and corky ringspot, and study genetics, identify co-segregating markers and develop selection methodology. Identify alternate crops and weedds that harbor the purple top pathogen (phytoplasma) and evaluate the impact of the disease on different cultivars of potatoes grown in the Columbia Basin. Use recently developed, improved procedures for determining the incidence of strains of potato virus Y (PVY) in large numbers of potato samples from production fields and in plants grown from seed lots submitted to the seed lot trials. 1b.Approach (from AD-416) Analyze as yet unidentified phenolics in potato skins using HPLC and MS-MS (mass spectrometry). We have found markedly different unknown compounds in some wild species, and we will attempt to identify them. We will explore whether certain treatments, including chilling tubers, or spraying tubers with salicylic acid or methyl jasmonate substantially increase or alter the phenolic profile. Screen germplasm in the field and greenhouse. Use field inoculation and greenhouse inoculation methods. Determine the relationship of field and greenhouse studies. Search for molelcular markers associated with resistance. Use polymerase chain reaction methodology to screen segregating progeny. Use the polymerase chain reaction (PCR) for detection of the phytoplasma in potato samples, alternate crops, and weeds. Tissue samples will be tested in this laboratory by reverse transcription polymerase chain reaction (RT-PCR) for strains of PVY. Documents trust with WA State Potato Commission. Logs 30458, 30459, 31390, 31395. 3.Progress Report This report serves to document research conducted under a trust agreement between ARS and the Washington State Potato Commission. Additional details of research can be found in the report for the parent project 5354-21220-002-00D “Potato Variety Improvement through Gene Transfer and Virological Studies.” The potato yellows syndrome, caused by the potato purple top phytoplasma, is economically important in the Columbia Basin of Washington and Oregon. Our work has shown that all of the major potato cultivars grown in the Basin are susceptible to the phytoplasma and develop symptoms typical of the disease. Additional work has shown that the phytoplasma is transmitted to daughter tubers of most cultivars at a relatively high rate and that these secondarily-infected plants can then produce phytoplasma-infected progeny tubers. This finding documents a possible mechanism for persistence of the phytoplasma in potato-producing areas. We have screened advanced and primitive germplasm for resistance to black dot disease caused by the fungus Colletotricum coccodes. The fungus penetrates the underground parts of the stems and through wounds on the above ground stems by wind abrasion. As the plant shifts into a senescing mode, the fungus becomes active in rotting underground stems and populating the dried stems with very durable soil-surviving microsclerotia. The name comes from the organism’s production of microsclerotia which look like speckles. We found that different potato genotypes restricted spread of the fungus up the stem to varying degrees. Some clones allowed the fungus to travel all the way up the stems while others blocked the movement partially or fully. The development of new varieties with resistance to black dot would restore the 20-40 % of yield that the growers lose to this pathogen. In addition, black dot can colonize tubers, meaning that the tubers themselves are unmarketable or serve as an entry point for other rotting organisms that spread rapidly in storages. Folate deficiency is a leading cause of major birth defects and is implicated as a risk factor for heart attacks and strokes. We screened over 80 potato genotypes for folate concentrations. Over 3-fold range was found between high and low folate containing germplasm. Folate concentrations, unlike some other vitamins, was found to be stable during long term potato storage. We are also characterizing potato phytonutrients and identified an over 10-fold difference in total phenolics and even greater differences in individual phenolics. One of the highest phenolic containing genotypes out of the many screened so far is a purple-fleshed advanced breeding line from our program.