Location: Sugarbeet and Potato Research
2021 Annual Report
Objectives
Objective 1: Delineate and integrate the molecular processes that control cytokinin content and their biological activities during tuber dormancy progression and wound-healing.
Sub-Objective 1-1: Determine changes in tuber meristem cytokinin content and expression of genes encoding cytokinin biosynthetic enzymes during dormancy progression.
Sub-Objective 1-2: Determine changes in the expression of cytokinin-responsive histidine kinase genes and the acquisition of cytokinin sensitivity during tuber dormancy progression.
Sub-Objective 1.3: Determine changes in cytokinin content and the expression of genes encoding key cytokinin metabolic enzymes in tuber tissues following mechanical wounding.
Objective 2: Quantify nitric oxide release during potato storage and handling and determine nitric oxide involvement in tuber dormancy progression and wound-healing.
Sub-Objective 2.1: Determine the release and role of NO in potato tuber dormancy exit.
Sub-Objective 2.2: Determine the release and role of NO in the potato tuber wound-healing response.
Objective 3: Determine the effects of postharvest storage on process quality and nutritional composition of advanced breeding lines in collaboration with public potato breeding programs (non-hypothesis driven).
Sub-objective 3.1: Determine storage and processing characteristics of advanced breeding lines.
Sub-objective 3.2: Screen advanced potato breeding lines for cold storage potential.
Objective 4: Determine the total antioxidant and ascorbic acid (vitamin C) contents of advanced breeding clones at harvest and during temperature-controlled storage (non-hypothesis driven).
Objective 5: Identify and characterize the physiological and molecular mechanisms that regulate and maintain meristem dormancy in potato tubers and evaluate strategies to inhibit tuber sprouting during storage.
Approach
Worldwide, the potato ranks fourth among the major food crops. Global potato production exceeds 364 million metric tons (FAOSTAT, March, 2013) and U.S. production exceeds 437 million cwt (USDA-NASS, January, 2013) of which over 400 million cwt worth an estimated $2.01 billion are harvested in the fall. Over 70% of the fall potato crop is placed into storage for year-round use. Unlike other major food crops, potatoes are stored in a fully hydrated and highly perishable form. Postharvest losses routinely approach 10% of the stored crop and occur through both physiological and disease-related processes. Two of the most important physiological processes affecting potato storage and market quality are dormancy/sprouting and wound-healing. Despite the severity of these losses, management strategies and technologies employed to combat these problems were empirically derived, are several decades old and do not effectively meet today’s consumer or industry demands to control damage, minimize physiological deteriorations, and reduce disease problems. Further improvements in postharvest storage technologies are hindered by ignorance of the biological mechanisms underlying these physiological processes. The goals of this project are to identify critical molecular, biochemical and physiological mechanisms controlling tuber dormancy/sprout growth and wound-healing and, ultimately, to genetically, chemically, or physically manipulate these rate-limiting processes to develop improved methods to maintain potato nutritional and processing quality during storage. Specific goals are: 1) Identify the cognate processes that control cytokinin content and activity during postharvest storage/wound-healing, and 2) Determine the involvement of nitric oxide in tuber dormancy progression and wound-healing.
Progress Report
This report documents progress for the bridge project (3060-21420-008-00D), which continues research from two merged and expired projects (3060-2140-007-00D; 3060-43440-013-00D), while the research plan for the next five years undergoes peer panel Office of Scientific Quality Review.
The bridge project includes five objectives: Objectives 1, 2 and 5 were transferred from project 3060-2140-007-00D “Improving Potato Nutritional and Market Quality by Identifying and Manipulating Physiological and Molecular Processes Controlling Tuber Wound-Healing and Sprout Growth”; both investigators responsible from this project retired during the lifecycle of the project (refer to the fiscal year 2020 final report). Objectives 3 and 4 were transferred from project #3060-43440-013-00D “Improved Potato Market Quality Through Germplasm Processing Evaluations and Optimized Storage Technologies”.
Limited progress was made towards Objectives 1, 2 and 5 due to remaining critical vacancies and reconsideration of research objectives on tuber dormancy and wound healing in the new project plan that is currently under Office of Scientific Quality Review. However, in fiscal year 2021, significant progress was made on planning and initiating experiments in line with the objectives of the proposed project plan. Several collaborations with university researchers and potato industry stakeholders were established to conduct research on potato postharvest physiology. Two of these collaborative research projects on tuber dormancy/sprouting and wound healing have received awards from the ARS - State Partnership Potato Research Program. Potato tubers were grown in the greenhouse for preliminary experiments and method optimization for dormancy and wound healing research. Partnering with university collaborators and local growers, potato cultivars were planted in the field and greenhouse to obtain tubers in the fall for postharvest physiology research.
Significant progress was made in the non-hypothesis driven Objectives 3 and 4. Cooperative research has been fostered among university breeding programs, ARS potato breeding programs, and potato industry grower and processing stakeholders. Annual processing quality evaluations were performed throughout storage among advanced breeding clones and new potato varieties representing public breeding programs (Objective 3.1). Potato clones possessing improved processing quality and cold storage potential were identified (Objective 3.2). Processing quality of fry and chip clones was assessed among Potatoes U.S.A. sponsored National Chip and Fry field and processing trials (Objective 3.1). Tuber antioxidant (vitamin C) concentrations and anti-quality compounds including glycoalkaloids were quantified among new potato clones at harvest and throughout storage (Objective 4). This cooperative evaluation process has streamlined the introduction of new potato cultivars with superior processing characteristics in storage.
Accomplishments
1. Potato post-harvest quality evaluations and release of new potato cultivars. Acceptable processing quality after storage is an essential attribute of a successful potato variety. The standardized evaluation procedures developed and used by ARS scientists in East Grand Forks, Minnesota, have been an important component of the overall process evaluation and release of new cultivars by federal and state cooperators nationwide. In the past year, in support of federal and non-federal public breeding/screening programs, 133 advanced breeding lines were analyzed for storage/processing quality at multiple storage temperatures and durations. Data from these analyses will contribute to the release of new potato varieties. These improved varieties offer significant benefits to both producers and processors and should be widely adopted by the potato industry.
2. Potato cultivars with reduced acrylamide concentration identified. Acrylamide is an unwanted and potentially toxic by-product produced when carbohydrate-rich foods are processed at high temperatures. Several potato clones exhibiting excellent processing characteristics and very low acrylamide levels were identified among entries in the National Fry Processing Trials by ARS scientists in East Grand Forks, Minnesota. These clones will be evaluated in more detailed trials and may be candidates to replace currently used varieties in the commercial production of processed potato products. Eventual adoption of these varieties and consequent reduction in the acrylamide concentration of potato products will benefit both producers and consumers.
3. A new research plan for potato postharvest physiology was developed. The successful long-term storage of potatoes is dependent on the physical and physiological integrity of the harvested tuber. Two of the most important physiological processes that adversely affect postharvest tuber quality and nutritional value are tuber dormancy/sprouting and wound-healing. The new research project aims to identify critical molecular, biochemical and physiological mechanisms controlling tuber dormancy/sprout growth and wound-healing and, ultimately, manipulate the rate-limiting processes to develop novel treatments and management strategies for maintaining potato nutritional, processing and market quality. Significant progress was made on planning and initiating experiments in line with the objectives of the proposed project plan. Several collaborations with university researchers and potato industry stakeholders were established with ARS scientists in East Grand Forks, Minnesota. Potato tubers were grown in the greenhouse for preliminary experiments and method optimization for dormancy and wound healing research.
