Location: Potato, Pulse and Small Grains Quality Research
2025 Annual Report
Objectives
Objective 1: Resolve the underlying changes in transcriptome and metabolome profiles, and identify regulatory genes, gene-networks and metabolic pathways responsible for wound-healing and tuber sprouting in potato during postharvest storage.
Sub-objective 1.A: Determine the effects of exogenous ethylene treatment on tuber dormancy progression and identify molecular mechanisms regulating dormancy/sprout growth by utilizing integrated transcriptome, phytohormone, and metabolome analyses.
Sub-objective 1.B: Determine the effects of exogenous DMN and CIPC treatment on tuber dormancy progression and identify genes and metabolic pathways regulating dormancy/sprout growth by utilizing integrated transcriptome, phytohormone, and metabolome analyses.
Sub-objective 1.C: Determine changes in transcriptome and metabolome profiles in tuber tissues following mechanical wounding to identify regulatory genes and metabolic pathways involved in periderm development and wound-healing processes.
Objective 2: Evaluate and report the effects of postharvest storage on intrinsic processing quality and nutritional composition of advanced breeding lines in collaboration with public breeding programs, as a USDA-ARS direct mission of research support (non-hypothesis driven).
Sub-objective 2.A: Determine cold storage (< 7°C) potential and processing characteristics of advanced breeding lines.
Sub-objective 2.B: Screen advanced potato breeding lines for vitamin C and anti-quality compounds impacting food end-use.
Approach
Potato (Solanum tuberosum) ranks fourth among major food crops with annual global production exceeding 368 million metric tons (FAOSTATS, 2018). United States potato production exceeds 450 million hundredweight (cwt; USDA-NASS, 2018), of which 400 million cwt (~90%) with an estimated value of over $2 billion, are harvested in the fall. Because postharvest losses through physiological and disease-related processes routinely reach 10-15%, maintenance of postharvest quality is of prime concern to the potato industry. Current management strategies employed to combat these problems are several decades old and do not effectively meet today’s consumer or industry demands to control physiological deteriorations. Moreover, chemistries utilized to manage storage issues are under regulatory scrutiny and may not be available in coming years. Two physiological processes that adversely affect postharvest tuber quality are dormancy/sprouting and wound-healing. Further improvements in postharvest storage technologies are hindered by limited empirical information on biological processes underlying tuber meristem dormancy and wound-healing. Thus, the proposed research project is essential to identify the critical molecular, biochemical, and physiological mechanisms controlling tuber dormancy/sprouting and wound-healing and, ultimately, to manipulate these rate-limiting processes to reduce postharvest deteriorations of potato (Figure 1). Studies will be conducted to achieve the following objectives: (a) investigate effects of exogenous postharvest treatments (i.e., ethylene, 1,4-dimethylnaphthalene, and isopropyl-N-(3-chlorophenyl) carbamate) on tuber dormancy progression and sprouting using distinct cultivars for dormancy characteristics and utilize transcriptome and metabolome profiling to determine changes induced by these treatments, (b) identify the molecular mechanisms associated with mechanical wounding and wound-healing processes by utilizing transcriptome and metabolome profiling, and using a natural elicitor (water soluble chitosan) and distinct cultivars for periderm development and wound-healing characteristics. Equally important to the potato industry is development of superior germplasm for introducing new varieties with proven storage characteristics. Effective evaluation of new clones requires high-throughput screening facilities, specialized equipment, and resources. Therefore, we collaborate with public breeding programs to screen advanced breeding material for the postharvest storage potential, food quality and safety characteristics.
Progress Report
This is a final report for the project plan for its lifecycle (started 1 April-2022, ended in July-2025).
Objective 1: Resolve the underlying changes in transcriptome and metabolome profiles, and identify regulatory genes, gene-networks and metabolic pathways responsible for wound-healing and tuber sprouting in potato during postharvest storage.
Sub-objective 1.A: Determine the effects of exogenous ethylene treatment on tuber dormancy progression and identify molecular mechanisms regulating dormancy/sprout growth by utilizing integrated transcriptome, phytohormone, and metabolome analyses.
For this project, tubers of cv. Russet Burbank (Solanum tuberosum L.) were subjected to continuous ethylene treatment for 15 weeks, followed by 3 weeks of airflow. 136 tuber tissue samples were collected at 3-wk intervals for transcriptome and phytohormone analyses. Tuber sprouting was recorded weekly. Results indicated ethylene treatment effectively suppressed sprouting and triggered tissue-specific transcriptional responses and caused decrease in transcript abundance of genes involved in auxin, cytokinin, and gibberellin pathways. In contrast, transcript abundance of genes involved in ethylene biosynthesis and signaling, abscisic acid and jasmonic acid pathways increased. Hormone profiling results aligned well with the gene expression results, with reduced zeatin and gibberellin A6 levels and elevated jasmonic acid derivatives. This study provides a molecular framework for ethylene-based sprout suppression that could improve future potato postharvest storage strategies.
Sub-objective 1.B: Determine the effects of exogenous 1,4-dimethylnaphthalene (DMN) treatment on tuber dormancy progression and identify genes and metabolic pathways regulating dormancy/sprout growth by utilizing integrated transcriptome, phytohormone, and metabolome analyses.
For this study, Russet Burbank tubers were treated with single or multiple DMN applications. A subset of tubers was monitored weekly for sprout growth. A total of 99 tuber tissue samples were collected in 3-wk intervals and used for transcriptome and hormone profiling. Sprout growth results indicated multiple DMN applications are needed to suppress sprouting. Transcriptome analysis revealed DMN extensively modulated gene expression; functional enrichment analysis highlighted the significant impact of DMN on hormonal pathways. Hormone profiling data complemented these findings, demonstrating DMN treatment altered the levels of hormones, including auxin, abscisic acid, cytokinin, gibberellin, jasmonic acid, and brassinosteroids. In another study, Russet Burbank tubers were treated with DMN and methyl jasmonate (MeJa) alone or in combination to determine their effects on sprout growth. Tuber tissues (meristem and flesh) were collected 0-21 days after treatments to determine the changes in transcript and biochemical analyses. Results indicated significant sprout suppression with MeJa and DMN+MeJa treatments. The treatments resulted in increased abundance of transcripts associated with abscisic acid, brassinosteroids, and dormancy regulation, while transcript abundance of cytokinin and cell cycle genes decreased, especially with DMN treatment. Lower metabolic activity related to carbohydrate metabolism was observed in bud meristem tissues when compared to tuber flesh.
To complement Sub-objective 1.A-B, an experiment was conducted to determine the impact of potato storage environment on tuber microbiome and dormancy. Russet Burbank tubers were stored under two temperatures (8C or 21C), and tuber tissues were collected for microbiome and biochemical analysis. Results showed that storage temperature and storage duration significantly affected tuber microbiome. Beneficial bacterial species with potential roles in tuber sprout suppression were identified. Another experiment was conducted to determine the efficacy of essential oils (organic spearmint, organic oregano, and organic sweet orange) treatments for tuber sprout suppression. Essential oils were applied either thermally (using Russet Burbank and Ranger Russet tubers at different stages of dormancy) or via air-wicking method (using mini tubers of Russet Burbank, 20-wks after harvest). Results revealed that when essential oils applied thermally, oregano essential oil was effective in temporary suppression of tuber sprout, while spearmint essential oils was effective until five weeks after treatment when applied using air-wick method. Sugar and biochemical analysis suggested that essential oils impact sugar metabolisms and stress protective metabolites in tuber tissues and affect tuber sprouting.
Sub-objective 1.C: Determine changes in transcriptome and metabolome profiles in tuber tissues following mechanical wounding to identify regulatory genes and metabolic pathways involved in periderm development and wound-healing processes.
For the Sub-objective 1.C, an experiment was conducted to determine the efficacy of two natural elicitors (chitosan oligosaccharide and cranberry pomace extracts) on wound-healing of potato tuber tissues (Russet Burbank and Russet Norkotah). Results revealed that both elicitor treatments are effective in enhancing deposition of protective compounds in cell layer of wounded surface of tubers. In a follow-up experiment, optimized natural elicitor treatments were used to study wound-healing responses of five cultivars (Chieftain, Dakota Rose, Dakota Ruby, Red LaSoda, Red Norland). Wounded tissues were allowed to heal 0-9 days and tissues were collected to determine wound-healing responses by histological and biochemical analyses. Both elicitor treatments increased deposition of hydroxycinnamic acid and antioxidants and accelerated initial wound-healing responses. Another experiment was conducted to understand the role of nitric oxide in tuber wound-healing. Results indicated that nitric oxide plays an important modulatory role in wound-healing response and nitric oxide related chemicals can be utilized as exogenous treatments to regulate wound-healing of tubers. Another experiment is conducted in the field and greenhouse to investigate the impact of healing cut potato seed tuber pieces before planting on sprout emergence and overall performance of the potato crop. Performance of seed pieces for emergence, growth, and tuber yield were determined using 3 cultivars in 2024, and to validate the results an experiment continued in 2025.
Objective 2. Evaluate and report the effects of postharvest storage on intrinsic processing quality and nutritional composition of advanced breeding lines in collaboration with public breeding programs, as a USDA-ARS direct mission of research support (non-hypothesis driven).
Substantial progress was made evaluating and reporting the effects of postharvest storage on intrinsic processing quality and nutritional composition of advanced breeding lines in collaboration with public breeding programs. Storage and processing evaluations were made on advanced french fry and potato chip breeding lines from multiple potato breeding programs. Evaluations were performed on tubers stored for up to eight months at 48F, 45F, 42F, and 40F. Data was collected on specific gravity and fried product quality. Spectrophotometric data was collected for chip samples, and reflectance data for french fry samples. Both of these methods are industry standards for assessing appearance of finished fried products. Glucose and fructose levels in addition to asparagine content were evaluated in all samples processed as nonenzymatic chemical reactions between reducing sugars and asparagine occur at frying temperatures resulting in an undesirable dark final product with elevated acrylamide levels. Testing was completed to quantify asparagine and acrylamide levels in specific samples. This cooperative evaluation process has streamlined the introduction of new potato cultivars with superior processing characteristics in storage and has been considered gold-standard by the potato industry.
Accomplishments
1. Identifying effective chemical treatments for suppressing premature potato tuber sprouting. The majority of potato tubers produced in the U.S. are placed in storage for year-round use. As tubers age, they develop sprouts and lose their nutritional quality. Commercial storage facilities usually use sprout inhibitors to prevent premature sprouting during long-term storage. Due to increasing regulatory concerns about the most commonly used sprout inhibitor treatment, finding effective and safer treatments is among the priorities of the potato industry in the U.S. ARS scientists in Fargo, North Dakota, have identified optimum utilization of sprout inhibitor treatments such as continuous ethylene, 1,4-dimethylnaphthalene, and methyl jasmonate during long term storage of potato tubers. The underlying mechanisms of these treatments for suppressing tuber sprout growth were also identified at the molecular and biochemical level. Outcomes of this research will help potato industry to optimize postharvest storage strategies and to minimize premature sprouting related losses.
2. Organic oregano essential oil can be utilized to manage potato tuber sprouting. Essential oils have emerged as potential sprout control treatment of potato tubers during long term storage and specifically used widely for organic market. For commercial and wider application of essential oils, it is important to optimize time and method of their application as well as determine their efficacy for tuber sprout control. To attain that objective, ARS scientists in Fargo, North Dakota, collaborated with University of Idaho scientists to investigate the efficacy of organic oregano, organic spearmint, and organic sweet orange essential oils to suppress sprout growth of potato tubers during long term storage. Higher efficacy of organic oregano essential oil for temporary sprout growth cessation, specifically with thermal aerosol application method was determined. Outcomes of this research suggested that utility of organic oregano essential oil is promising, particularly as a rescue treatment for controlling sprout growth of potato tubers that have broken dormancy and started sprouting at later storage stages.
3. Postharvest studies on potato tuber microbiome identified bacterial species with potential benefits for protecting tuber quality. Potato tubers are stored with minimal cleaning after harvest, carrying both beneficial and harmful microbiome in tuber tissues from field to storage. These microbial species present in tuber tissues potentially impact storage and nutritional qualities of tuber, but little is known about their role in tuber qualities. Furthermore, the effect of storage environment on tuber microbiomes has not been explored largely. ARS scientists in Fargo, North Dakota, investigated the effect of storage temperature and duration on microbiomes in different tuber tissues and how they influence tuber sprouting. Differences in microbial species composition across different tuber tissues under different storage temperatures and different storage durations were determined. Bacterial species with potential beneficial roles in sprout growth control and potato disease management were also identified, which can be investigated in future research as part of postharvest management strategies of potato tubers.
4. Natural elicitors accelerated wound-healing responses of potato tuber tissues. Wounding of potato tubers during harvest or postharvest handling leads to rotting or complete loss of tuber. Currently, there is no practical treatment strategy to improve wound-healing of potato tubers at postharvest storage and potato growers need effective strategies to minimize wounding related tuber losses. ARS scientists in Fargo, North Dakota, have identified two natural elicitors and optimized treatment strategies to accelerate wound-healing responses of potato tubers. Laboratory analysis also indicated how these elicitor treatments enhance the deposition of wound-healing related metabolites in open cut surfaces of the tuber tissues. Further research is being carried out in collaboration with potato growers and industry partners to optimize their commercial utilization in potato storage.
5. Wound healing performance screening of agronomically relevant potato cultivars identified fast and slow healing cultivars. Wounding related postharvest losses are evident among all potato cultivars. However, the wound-healing trait of the tubers varies widely among potato cultivars. For potato growers and industry partners, having knowledge on wound-healing characteristics of specific potato cultivar is necessary to optimize their postharvest strategies. ARS scientists in Fargo, North Dakota, screened several agronomically relevant potato cultivars and identified fast and slow healing cultivars. Furthermore, biochemical indicators related to fast wound-healing response of potato tubers were also determined, which will support future breeding initiatives to develop new cultivars with improve wound-healing trait.
6. Optimum pre-planting curing conditions for cut seed tubers were determined. The common potato planting practice involves cutting seed tuber into pieces and immediately planting them in the field. This planting practice is reliable under favorable environmental conditions but can cause severe decay of seed tuber under unfavorable conditions. Potato growers have expressed serious concerns about seed decay related losses in the field as decay of seed tuber pieces adversely impact emergence, growth, and overall productivity of the potato crop. Healing of cut surfaces of seed tuber pieces prior to planting can protect them from decay and to attain this, ARS scientists in Fargo, North Dakota, optimized pre-planting wound-healing conditions for agronomically relevant potato cultivars by conducting field and controlled environment greenhouse experiments in collaborations with potato growers. Impacts of pre-planting wound-healing conditions on emergence and performance of potato crops were also determined, and research will be continued to gain more insights into pre-planting curing practices.
7. Evaluation of potato processing quality under differing storage conditions and timing among new 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 support of federal and non-federal public breeding/screening programs, advanced breeding lines from public potato breeding programs 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.
8. Potato cultivars with reduced acrylamide. Acrylamide is an unwanted and potentially toxic by-product produced when carbohydrate-rich foods are processed at high temperatures. Among entries in National Fry Processing Trials, several clones exhibiting excellent processing characteristics and very low acrylamide levels were identified 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. Eventually, adoption of these clones and consequent reduction in the acrylamide concentration of potato products will benefit both producers and consumers.
9. Examining glycoalkaloid concentrations of new potato varieties. Glycoalkaloids are a naturally occurring secondary metabolite found in potato tissues, but tuber concentrations exceeding 20 mg/100 g fw-1 are not safe for human consumption (bitterness). Glycoalkaloid concentrations were measured from hundreds of cultivars representing U.S. public breeding programs. Variability in tuber glycoalkaloid concentrations was also quantified from advanced chip breeding lines sampled from North Dakota, Wisconsin, and Michigan potato chip production locations. Data reported to breeders and potato processing stakeholders will help ensure new potato varieties meet glycoalkaloid concentrations safe for human consumption.
Review Publications
Dogramaci, M., Bill, M., Fortini, E., Sarkar, D., Kandel, S.L. 2025. Postharvest storage conditions impact potato tuber microbiome and dormancy progression. Postharvest Biology and Technology. 230. Article 113766. https://doi.org/10.1016/j.postharvbio.2025.113766.
Dogramaci, M., Sarkar, D., Fortini, E., Hendricks, R., Olsen, N. 2025. Utilization of essential oils to control sprout growth of potato tubers. American Journal of Potato Research. https://doi.org/10.1007/s12230-025-10007-9.
Dogramaci, M., Oliveira, T., Fortini, E., Sarkar, D., Wyatt, N.A., Leonard, E., Tharayil, N., Finger, F. 2025. Transcriptomics and targeted metabolomics uncover hormonal regulations of potato (Solanum tuberosum L.) tuber dormancy progression under ethylene treatment. Postharvest Biology and Technology. 23. Article 113875. https://doi.org/10.1016/j.postharvbio.2025.113875.