OPTIMIZING TUBER SET AND SIZE DISTRIBUTION FOR SEED, FRESH, AND PROCESSING MARKETS
2009 Annual Report
1a.Objectives (from AD-416)
Characterize factors that affect the quality or nutritional value of potatoes.
1b.Approach (from AD-416)
Tubers from multiple genotypes will be analyzed for quality or nutritional value. Genotypes with traits useful to the potato industry such as tuber size and set or superior phytonutrients with be characterized. Factors influencing or controlling trait expression, such as molecular, developmental and environmental control will be characterized. Documents SCA with WSU. Formerly 5354-21220-002-30S (6/08).
Premier Russet, GemStar Russet (A9014-2), Defender (A90586-11) and Alturas (A82360-7) are newly released cultivars (since 2002) from the Pacific Northwest Potato Variety Development Program. Research to define the effects of tuber maturity on wound-healing ability and to determine the physiological, biochemical, and molecular bases for resistance/susceptibility to cold-induced deterioration in processing quality and shrink among these cultivars is underway. Late storage mottling of Premier appears to be a consequence of accelerated aging. Premier develops mottling after approximately 190 days in storage. We recently determined that mottled tissue has low starch and dry matter, high asparagine, low protein, high glucose, and high respiration. Because of the elevated respiration, oxygen becomes limiting in mottled tissue and the disorder can progress to pockets of blackheart in severe cases late in the storage season (late June/early July). We believe this physiological disorder is related to growth and development under relatively high temperatures. We plan to initiate studies in 2010 to determine the effects of soil temperature during growth on subsequent mottling in storage. Studies are also underway to evaluate the mechanisms of resistance to low temperature sweetening (LTS) in newly released varieties. GemStar and Premier Russet are highly resistant to LTS; however, the mechanisms appear quite different. Gemstar resists LTS by building up relatively high levels of sucrose in cold storage without conversion to glucose and fructose. The basis for LTS resistance of Premier appears to be an inherent ability to resist starch breakdown, thus maintaining low levels of both sucrose and reducing sugars. The activities of key enzymes (invertase, starch phosphorylase) involved in LTS, along with their expression levels in response to low temperature stress, are being analyzed. This work may provide multiple strategies (with associated markers) for selecting for LTS in the breeding program. Studies to assess the effects of N nutrition (rate and timing) on end-of-season tuber maturity and associated effects on wound-healing ability and retention of processing quality are also underway. We began harvesting foliar and tuber samples (10-day intervals) in mid June. Gravities are being measured and samples processed for carbohydrate analysis. These data will help quantify the effects of management on attainment of physiological maturity in relation to storability and processing quality. This project was monitored through phone calls, meetings and emails.