NE1731: Collaborative Potato Breeding and Variety Development Activities to Enhance Farm Sustainability in the Eastern US
(Multistate Research Project)
NE1731: Collaborative Potato Breeding and Variety Development Activities to Enhance Farm Sustainability in the Eastern US
Duration: 10/01/2017 to 09/30/2022
Statement of Issues and Justification
STATEMENT OF ISSUES AND JUSTIFICATION
Importance of work - This multidisciplinary research project helps small-, medium- and large-scale potato growers supply high quality, highly nutritional products to customers, while maintaining economically and environmentally sustainable production practices. We will provide farmers new potato varieties to solve production problems and meet industry and consumer preferences. These varieties will have better yields, enhanced fresh market, processing or value-added traits, and better pest and abiotic stress resistances resulting in improved productivity and/or reduced chemical inputs. We have a solid track record in producing new potato varieties that have been commercially accepted. For example, the varieties Lamoka, Caribou Russet, Reba, Keuka Gold, Lehigh, Pike, Andover, Harley Blackwell, Waneta, Peter Wilcox, Sebec, Strawberry Paw, Pinto Gold, and Marcy have enjoyed recent success in the marketplace and most are produced on significant acreage in the east. Additional advanced breeding clones in our evaluation pipeline have the potential to provide significant benefits for potato producers. We propose to continue developing improved potato breeding and phenotyping technologies using our collaborative multidisciplinary regional approach to breed, select, and develop improved potato varieties to enhance marketing opportunities and reduce farm dependence on costly agricultural chemicals. This will lead to a more economically and environmentally sustainable potato production system.
Importance of potato production to the Eastern US - Research benefiting the Eastern potato industry impacts markets associated with over half of the US population. Consumers benefit from the release of new potato varieties that provide high quality products, facilitate efficient production, and provide improved pest resistance resulting in less pesticide use. From a farm economy perspective, potato ranks among the top three vegetable crops produced in FL, ME, NC, NY, OH, PA and VA. Cash farm receipts for eastern potatoes are ca. $500 million annually (USDA NASS) with economic multiplier effects many times this amount. However, achieving this level of productivity in the East is difficult as production occurs under a wide range of environmental conditions, ranging from the winter crop in southern FL, to out-of-field marketed summer and fall chipping crops in NC, VA, and elsewhere, to the fall storage crops of ME, NY and PA. This creates diverse variety needs. Fresh market production remains a significant part of the industry (e.g. 15, 25, 50, 60% of ME, NC, OH, PA’s crops, respectively); however, 43 percent of U.S. chip production occurs in the east (NPC Potato Statistical Yearbook). Processing, primarily for French fries, accounts for 60% of ME utilization (USDA NASS). ME and NY maintain high quality seed potato industries that service most of the East’s seed potato markets.
Needs as indicated by stakeholders - All Eastern potato breeding programs utilize direct input from growers, processors, and industry groups (e.g., National Potato Council and Potatoes USA, state grower associations, processors, large-scale corporate farms, and individual growers, etc.) to provide input and establish priorities for their breeding efforts. These groups typically provide over $300,000 in annual matching grant support to this research effort. Our grower and industry stakeholders have consistently indicated that they need improved varieties for both fresh and processing markets. New varieties resistant to abiotic stress, diseases, and insects are high priorities. Stakeholders have always played a key role in defining the objectives of our potato breeding, evaluation, and variety development efforts and we recognize that variety adoption is impossible without active interaction between researchers, extension, growers, and industry.
Stakeholders place a high priority on the development of new red-skinned and specialty varieties. A premium-priced market exists for red-skinned and novelty varieties. For reds, the skin color needs to be bright and stable in storage. Resistance to skinning, netting, and silver scurf are especially important. Novelty varieties (e.g., fingerlings, purple-skinned, and multi-colored-flesh types) are growing in popularity in the high-value, direct-sale market. Better-adapted novelty varieties would offer new marketing opportunities to many Eastern growers, especially small-scale growers that specialize in direct sales to consumers. New varieties containing desirable market quality along with multiple resistances to insects, pathogens and stress would provide better performance without chemical inputs in the growing organic industry.
Two distinct marketing opportunities exist for chip potatoes in the Eastern region. Potato producers from the mid-Atlantic and southern areas (e.g. FL, NC, VA, MD, NJ, and southeastern PA) sell their processing potatoes to chip factories directly following harvest. The variety requirements for these regions stress earliness, chip quality from the field, high tuber dry matter content, and tolerance to high temperatures during bulking. The cultivar Atlantic has dominated commercial production in these areas for many years; however, it is very susceptible to internal heat necrosis (IHN), a serious quality defect throughout many of the Eastern-coastal and Southeastern states. Stakeholders have made developing an improved variety to replace Atlantic a top priority and several recent releases and advanced selections from our programs are being evaluated for this purpose. Contrasted with the south, processing growers from the northern states (PA, NY, and ME) store most of their crop before it is sold. These growers need high yielding, high specific gravity varieties with low defect levels and the ability to process into chips or fries from long-term cold storage. Snowden has been the standard storage chipping variety in northern regions for about 25 years. It combines high yield potential and specific gravity with reliable chip color through mid-term storage; however, it has weaknesses (e.g., scab susceptibility, stem and vascular defects, taste panel concerns, and poor chip quality from long-term storage). As a result, stakeholders have made developing an improved potato variety to replace Snowden a top priority.
Most of the russet- and French fry-type varieties developed in the western and mid-western states are poorly adapted to the East, as is the standard variety, Russet Burbank. A major goal is to develop russet varieties with high yield, improved disease resistance, uniform long tuber shape, high specific gravity, low internal and external defects, and acceptable fry color under Eastern growing conditions. This is critical for Maine’s French fry markets and could allow expansion of French fry processing into other Eastern states.
In all market sectors, disease- and insect-resistance are needed for the Eastern potato production system. Foliar fungicide applications for control of late blight (Phytophthora infestans) and early blight (Alternaria solani) account for approximately 80% of the pesticides applied to Eastern potatoes during a typical growing season. These applications are costly to growers and may result in chronic environmental degradation and/or health problems for agricultural workers. Potato virus Y (PVY) has become more difficult to manage as new recombinant strains have been introduced from other production areas. This pest has been very costly for eastern seed potato producers. Likewise, new challenges have developed in managing bacterial soft rot (Pectobacterium and Dickeya spp.) throughout the eastern region. Improved varietal resistance would benefit growers as they deal with this challenge. Golden nematode (Globodera rostochiensis) is highly destructive to the potato crop and its spread is controlled by quarantine regulations. Once it becomes established in a production area (e.g. parts of NY, Canada, and Europe), potato production is impossible without varietal resistance. Cosmetic diseases of the potato tuber such as common scab (Streptomyces spp.), silver scurf (Helminthosporium solani), black scurf (Rhizoctonia solani), and powdery scab (Spongospora subterranea) can result in a crop that is unmarketable for seed or table use. Once the crop is in storage, storage decay caused by a range of pathogenic organisms (e.g., Pectobacterim, Phytophthora erythroseptica, Pythium spp, Fusarium spp., P. infestans, and A. solani) can cause complete and devastating losses to growers. Colorado potato beetle (CPB, Leptinotarsa decemlineata), aphids (e.g., Myzus persicae and Macrosiphum euphorbae) and leaf hoppers (Empoasca fabae) are commonly encountered insect pests that increase costs and reduce yield and quality in the East. Concerted efforts are needed to identify new genetic sources of resistance and incorporate them into productive S. tuberosum clones. Disease and insect resistant varieties provide an economical and environmentally sound alternative to pesticide use.
Advantages of a collaborative, multistate research project - This project is a highly collaborative effort involving seven states and four breeding programs in the East (see figure in Appendix 2). Our project promotes collaboration and communication among researchers and stakeholders – all with the aim of enhancing farmer’s ability to provide a safe and nutritious supply of potatoes to consumers in an environmentally sustainable manner that enhances profits and rural America. It addresses the needs of the small- medium- and large-scale growers, marketers, processors of the Eastern potato industry through a collaborative process of potato breeding, selection, evaluation, and variety release. Our overall goal is to develop an array of attractive, high yielding, disease- and insect-resistant, tablestock, processing and/or specialty-type potato varieties that can be produced by potato farmers in the East for this exceptionally diverse consumer base. Within this context, it is important to recognize that the Eastern US region is not only linked geographically, but is also closely linked through potato seed sales (from northern production areas), production (north and south), and product marketing (north and south). Thus, regional communication among scientists, farmers and industry members is critical for the variety development process.
A regional approach for potato breeding makes sense because potato production in the East spans a wide range of day-length, temperatures, soils, humidity, and moisture conditions. These conditions have dramatic effects on the performance and acceptability of potato breeding lines and varieties (Tai et al., 1993). Genotype by environment interactions must be evaluated to select new varieties with improved adaptation (Hill, 1975; Souza et al., 1993; Zobel et al., 1988). In addition to breeding, this project conducts collaborative selection and performance trials under diverse environmental conditions and a wide array of disease and pest pressures so that new potato varieties can be selected that are adapted to varying conditions of the East. Our research network facilitates the coordination of potato breeding and genetics research across seven states, two Canadian Provinces, and two federal agencies (two USDA-ARS laboratories and the AAFC research center in Fredericton, NB, Canada). Central to the project’s function are multi-site testing of breeding materials under diverse environmental conditions, sharing of breeding materials, and exchange of trial results.
Hybridization and selection are conducted within the region’s four breeding programs (ME, NC, NY, USDA-ARS). Each breeding program shares seedling populations as botanical seed or as seed tubers providing extensive germplasm exchange. Two to four selection cycles are conducted by each breeding program at their field sites; however, the diverse environments provided by regional cooperators are increasingly used to supplement the selection process via simultaneous early-generation selection in multiple environments. This facilitates selection of both broadly and specifically-adapted plant materials for the diverse eastern environments. As superior progeny are identified and more seed is available, they are evaluated for other traits under a wider range of environmental conditions. To accomplish this, selected clones are entered into the eastern regional potato variety trials to subject them to diverse growing conditions and learn more about their strengths and weaknesses, geographical adaptation, yield stability, and durability of their pest and disease resistance. The most promising lines are entered into commercial-scale demonstration trials to begin the final assessment for commercial potential.
The regional approach allows evaluation and selection of new potato varieties for diverse environments and markets that could not occur otherwise. It enables us to evaluate stability of performance over varieties and genotype x environment interactions. Broadly adapted, stress tolerant new varieties will be advantageous as climate change continues to unfold. Identification of highly productive, broadly adapted new potato varieties is the most desirable goal; however, identification of new varieties that perform well under specific, unique environmental or marketing conditions can also be valuable. Our approach addresses both of these needs.
Our project also provides a mechanism for screening regional selections for specific characteristics at a single location (e.g., early blight, late blight, and powdery scab resistance in PA; golden nematode resistance in NY; scab and viruses in ME) and multiple locations (e.g., chip quality in ME, NY, PA, and NC; internal heat necrosis resistance in NC, VA, FL, PA, NY). This collaborative evaluation system makes efficient use of scientific expertise available in the region, and results in more efficient release and adoption of new potato varieties. We have a robust project website and have developed a user-friendly web-based variety database that has become a model for the rest of the U.S. potato variety development programs (http://potatoes.ncsu.edu/NE.html).
Related, Current and Previous Work
RELATED, CURRENT AND PREVIOUS WORK
The NE-1231 Project and its predecessors have played a central role in Eastern potato variety development for many years. Appendix 1 summarizes the seventeen (seven fresh market, seven chipping and three russet/long-tuber types) potato varieties released from 2002 to 2016.
By way of example - two new chipping cultivars (Waneta and Lamoka) were released by NY in 2011. Both were extensively tested within NE-1231 and both were found to have chip color comparable to or better than the current industry standard, Snowden, as well as moderate to good resistance to common scab (Snowden is susceptible). Both are also resistant to golden nematode race Ro1 (Snowden is susceptible). Because Waneta and Lamoka performed well in NE-1231 environments and because growers heard NE-1231 evaluators speak favorably about them, industry interest in these two varieties has been remarkably high. Commercial seed growers have not yet been able to meet demand.
Adoption and seed multiplication takes considerable time in the potato industry, in part because vegetative multiplication is slow, and in part because growers need several years before they can determine whether a promising new variety will work for them (many agronomic practices need to be adjusted for any new variety to achieve optimal performance). Thus impacts occur over a long time period. Despite these limitations, recent Eastern releases were grown on 2,382 ME and NY seed acres during 2016 with a seed value of ca. $7.2M. The resulting seed crop has the potential to plant 23,823 acres in 2017 with a ware value estimated at $71.5M. Nationally, varieties produced by our long-term project were grown on 4,793 seed acres during 2016 with an approximate seed value of $14.4M Several varieties developed though our collective efforts are currently in the top 100 U.S. varieties for seed acres, including (acres, rank): Lamoka (2367, 10), Waneta (713, 29), Pike (359, 50), Lehigh (260, 57), Reba (170, 66), Caribou Russet (143,71), Keuka Gold (106, 79), Eva (95, 83), and Andover (74, 98).
NE-1231 productivity extends to research as well: over the past five years NE-1231 scientists have published 29 peer-reviewed articles. Each year the NE-1231 team also leverages regional funding to attract additional funding from the federal government and potato industry. During the last five years, NE-1231 scientists shared funding included $1,357K from the USDA-NIFA Special Grant for Potato Breeding Research and attracted an additional $1,528K from industry stakeholders.
The objectives and activities of related projects, such as NRSP-6 (introduction, preservation, distribution, and evaluation of Solanum species), NCCCR-215 (potato genetics), and WRCC-27 (potato variety development) are complementary to this project. NE-1231 scientists interact with these projects through exchange of promising germplasm, meeting participation, and sharing trial results as well as peer-reviewed research. There is a need for good communication between regions to take advantage of widely-adapted germplasm and share knowledge. Several NE breeders routinely attend the annual NCCCR-215 meeting in Chicago.
The National Coordinated Chip Trial (NCPT) and National Fry Processing Trial (NFPT) supported by Potatoes USA and SNAC International are new, industry-driven, nationwide initiatives to coordinate the development of new chip and French fry varieties. Both started in 2010 and are directed at speeding the development of improved varieties for these markets, while assuring that germplasm is widely evaluated at the national level. NE-1231 scientists contribute clones to these trials and host trial sites in NY, NC, ME and FL. NCPT and NFPT have proven useful in two important respects. First, they allow originating breeders to identify broadly-adapted clones much earlier than was possible before. Second, they provide publicity to the best clones – when a good clone is identified, the entire processing industry knows about it, not just the scientists in the region that developed it.
To address specific Southern chipping industry needs Potatoes USA established the Early Generation Southern Selection Trial (EGSS) during 2017. This two-year screening trial will act as a precursor to the NCPT. Breeding programs have been encouraged to submit clones for evaluation earlier in their program selection schemes in order to reduce lose of genetic variation with the intention of identifying material more suitable for the elevated temperatures in the Southern US. NC was selected as the screening location for year 1. CA and NC will evaluate the best performing clones from this trial in year 2. Those clones surviving the year 2 evaluation in this trial will then be sent on to the NCPT for broader national screening in year 3.
The incorporation of disease resistance into varieties with desirable horticultural characteristics is of immense importance. The breeders in the NE-1231 Project have succeeded in incorporating disease resistance into many of the recently released varieties and clones now being tested. Priority disease and pest resistance breeding goals for our region continue to include resistances to: late blight, common scab, golden nematode, and potato virus Y. Although progress has been made in developing and introducing new varieties with combined disease resistance, favorable horticultural traits and desirable processing qualities, large-scale commercial adoption is hampered by marketing and seed production constraints. Our project intends to continue its focus on enhancing disease/pest resistance of potato while continuing to meet the diverse marketing needs of the Eastern fresh market (e.g., whites, reds, russets, organic and specialty varieties, etc.) and processing (French fries and chipping from field and/or storage) industries. We are also developing additional information and programs to enhance commercialization of new varieties (e.g., web-based information, variety profiles, licensing procedures, etc.).
Fresh Market and Specialty Varieties. Excellent appearance and cooking quality are essential for fresh market. Resistance to common scab and other diseases which cause external blemishes is extremely important. Resistance to mechanical damage during handling is critical. Unique tuber skin and flesh color (e.g., red, purple, yellow, etc.) can enhance appeal and marketing opportunities. Methods for breeding for improved yellow-flesh characteristics have been developed (Haynes et al., 1994; Haynes et al., 1996). Yellow-flesh intensity is highly heritable in the diploid hybrid phu-stn population, indicating that intense yellow-flesh color can be developed in this population (Haynes, 2000). Total carotenoid content of yellow-fleshed diploid phu-stn clones ranged from 3 to 13 times of that found in the yellow-fleshed variety Yukon Gold (Lu et al., 2001). However, when utilized in 4x-2x crosses, the carotenoid content of the resultant tetraploid progeny, although higher than what is currently available, did not reach the same levels as in their diploid parents (Haynes et al. 2011). Flavor and sensory components of cooked potato can be compared with various analytical methods (e.g., Oruna-Concha et al., 2001; Jensen et al., 1999; Ulrich, et al., 2000; Vainionopaa et al., 2000); however, these methods have not effectively substituted for sensory evaluation. Our project routinely conducts sensory evaluation of advanced potato selections to assure that new releases meet the markets’ rigorous quality demands. Potatoes are naturally nutritious and rich in vitamin C; however, introgression of yellow-fleshed diploid phu-stn hybrids into S. tubersosum will increase tuber concentrations of carotenoids, and other phytonutrients that would be highly beneficial to human health. Improving the nutritional quality of potato is a long-term goal. Over the past 10 years, eight fresh market and specialty varieties have been released by this project (Appendix 1). Continued improvement is needed in the quality and pest resistance of potato varieties available to Eastern growers so that marketing opportunities can be expanded and production can be more profitable, while minimizing negative environment impacts.
Chipping and French Fry Processing. Selection of clones that maintain processing quality during cool temperature storage is a high priority and is a viable approach towards reducing sprout inhibitor and energy use. Diploid potato species which have long-term cold storage chipping ability [S. phureja and S. raphanifolium (Hanneman, 1993)] and other germplasm with resistance to sugar accumulation in cold storage are being used to improve the genetic base of chipping potatoes adapted to the East. Adapted French fry processing clones are being selected from crosses conducted in ME and other states. New chipping varieties with high yields, high tuber dry matter, reduced susceptibility to bruising, and resistance to IHN are being developed by all Eastern breeding programs. Our research has shown that there is no significant correlation between susceptibility to IHN and either total yield or specific gravity in commercial potato germplasm (Henninger et al., 2000) and that the diploid hybrid population of S. phureja x S. stenotomum (phu-stn) can be used to expand the genetic base for chipping potatoes and reduce IHN problems for growers (Haynes et al., 1995; Sterrett et al., 2002). Research by McCord et al. (2011a, b) and Schumann (2015) identified quantitative trait loci (QTL) linked to IHN in a population developed from a cross between Atlantic and B1829-5. A SNP-based map of this population enabled us to identify QTL for IHN and other agronomic and quality traits. Using the SNP gene annotations and the potato reference genome we have tentatively identified a candidate gene involved in IHN, vacuolar cation/proton exchanger 1a, that was closely linked to a QTL for IHN susceptibility. Over the past 10 years, six chipping and/or French fry processing varieties have been released by this project (Appendix 1). The varieties Lamoka, Waneta, Pike, Andover, Harley Blackwell, Sebec, and Marcy have been successful in the chip processing marketplace, and early indications suggest that Caribou Russet will be useful for fry processing.
Potato Diseases Constraining Eastern Production. Bacterial and fungal diseases such as late blight, early blight, scab (common, acid, and powdery), verticillium wilt, rhizoctonia (stem canker and black scurf), silver scurf, pink rot, soft rot (e.g. Pectobacterium and Dickeya spp.), dry rot (Fusarium spp.) and virus diseases (leafroll, potato viruses X and Y, corky ring spot) reduce the yield and quality of the Eastern potato crop. All currently available potato varieties are susceptible to one or more of these diseases. Resistance to fungicides previously used for disease control [e.g., mefenoxam resistance to pink rot (Fitzpatrtick and Lambert, 2006)] makes development of improved genetic resistance particularly important. Breeding and selection for improved disease resistance is a major focal area for the Eastern potato breeding programs and NE-1231. The impacts provided by successful development of high yielding, high quality and pest-resistant potato varieties are tremendous for Eastern growers (e.g., reduced costs, fewer losses, lower risk, etc.) and the public (e.g., less pesticide use, higher quality, etc.).
Insect Pests and Variety Resistance. Colorado potato beetle (CPB) continues to be the most serious insect threat to Eastern potato production because of the severe damage that it causes and because this insect has developed resistance to all insecticides deployed against it (Weber and Ferro 1994). Aphids, leafhoppers, fleabeetles, and other insect pests also cause significant losses. Research on resistance to insect pests in the East has focused on the incorporation of two complementary sources of resistance, trichome-mediated resistance from S. berthaultii (Bonierbale et al., 1992, 1994) and leptine-based resistance from S. chacoense (Sanford et al., 1997; Yencho et al., 2000). NY has made considerable progress incorporating glandular trichomes into useful varieties [e.g., NY released NYL235-4 as an insect resistant clone for use in germplasm improvement (Plaisted et al., 1992) and has released two insect resistant varieties for organic production (Prince Hairy and King Harry)]. Leptines, which are foliage-specific glycoalkaloids, also provide resistance against CPB. Leptines are coded by only a few genes (Sinden et al., 1986) and research to develop durable insect resistance by combining trichome-mediated and leptine-based resistance has been conducted in NC (Yencho et al., 2000).
Regional Evaluation and Modeling Efforts. Performance data obtained from collaborative trials in the NE-1231 project have provided a rich information source to carry out research on genotype x environment interactions in the East. The project has developed two sets of baseline data: one consisting of five industry standards that are grown at all sites; the other being "breeders choices" where each of the participating breeders indicates one to three advanced selections that are tested at all sites for that year. The analytical results provide considerable information on the interplay between genotype and environment. Tai et al. (1993) showed that linear regression was useful for evaluating the performance and adaptability of selections over a range of environments. AMMI (additive main effect and multiplicative interaction model)[Gauch, 1992]; BLUP (best linear unbiased predictor); and REML (residual maximum likelihood)[Genstat, 1993; Horgan, 1992] have been used to further analyze NE1231 trial data with the goal of better understanding genotype x environment interactions and helping us develop better selection tools for potato variety development in the region.
Conduct multidisciplinary conventional and molecular marker-assisted breeding, germplasm enhancement, and early-generation selection research to improve potato productivity and quality for important Eastern U.S. markets.
Comments: The overall goal of this project is to develop attractive, high yielding, disease- and/or insect- resistant potato varieties for fresh, processing, and/or specialty-type potato markets. Our research network involves eight states, four potato breeding programs and over 30 scientists in the Eastern US. Our project design encourages collaboration, pooling of regional resources, and increases communication among researchers and stakeholders. This highly collaborative, multistate variety development effort engages the scientific expertise available in the region as efficiently as possible, reducing the time necessary for variety development and commercialization. Over-arching outcomes of this project will be the development of economically and environmentally sustainable farming systems in East and an abundant supply of high quality and nutritious potatoes for consumers.
Use novel and improved potato germplasm to reduce the impact of economically important potato pests and abiotic stress in the Eastern US.
Evaluate yield, quality, and pest and abiotic stress resistances of preliminary and advanced potato breeding lines in experimental- and commercial-scale trials at multiple Eastern locations to aid industry adoption of new varieties.
Provide timely and relevant information to stakeholders through various means including the maintenance of a project website and a web-based potato variety performance database for use by researchers, extension, potato growers, and allied industry members.
Objective 1: Conduct multidisciplinary conventional and molecular marker-assisted breeding, germplasm enhancement, and early-generation selection research to improve potato productivity and quality for important Eastern US markets.
1a. Collaborative Potato Breeding, Selection, and Variety Development in the Eastern US.
Initial crossing and germplasm improvement will be conducted within the ME, NY, NC and USDA-ARS breeding programs (see Figure in Appendix 2). Parents, including wild or cultivated diploid germplasm, are selected for desirable yield, quality, and pest and abiotic stress resistance traits, as well as male and female fertility. Initial selection is done by each breeding program at their field sites. The diverse environments provided by regional cooperators are used to supplement the early-selection process and improve regional adaptation. For example, materials from the ME and USDA-ARS programs are screened in NC and FL for internal heat necrosis (IHN) resistance and materials from USDA-ARS are screened in PA for common scab resistance. Each program tests lines for 5 to 8 years and at multiple eastern sites to evaluate yield, quality, disease resistance, and other agronomic characteristics. Promising clones are entered into national trials (e.g. NCPT, NFPT) and the Eastern regional potato variety trials.
1b. Quantitative, molecular, genetic and biochemical studies to improve resistance to internal heat necrosis. Germplasm from the breeding programs will continue to be screened for IHN resistance in FL, NC, and VA. IHN screening methods have been outlined by Henninger et al. (2000), Sterrett et al. (2003), and Sterrett and Henninger (1997). Molecular markers linked to IHN resistance are being developed to facilitate breeding and selection. Research on QTL associated with IHN resistance will continue by testing these QTL and candidate genes in new populations segregating for resistance to IHN. The long-term goal is to develop markers for resistance to IHN that can be used in marker-assisted breeding.
Identifying physiological processes involved in IHN development may enable identification of genetic markers linked to IHN. Candidate physiological processes are production of reactive oxygen species (ROS) and the ROS scavenging system (Davies and Monk-Talbot, 1989), cell wall thickening and suberization (Baruzzini et al., 1989) and programmed cell death. These processes and associated enzymatic activities will be evaluated in IHN susceptible and resistant lines grown under stress versus non-stress conditions (VA). Data will be collected from key factors involved in the ROS scavenging system [catalase, peroxidases, and superoxide dismutase (Davies and Monk-Talbot, 1989)] and the phenylpropanoid pathway (phenylalanine ammonia-lyase, and peroxidases) that are involved in cell wall suberization (Bernards and Lewis, 1998). Loss of membrane integrity (leakage) and tuber anatomical changes (microscopy) will be investigated and related to IHN incidence and severity.
1c. Improving the chip quality and long-term cold storage processing ability genetic base. Improved chip and fry processing are high priority industry traits. A multi-site, parallel-selection approach will be used by the ME, NY, and USDA-ARS programs to identify chipping clones for the mid-Atlantic and SE states. Potatoes USA sponsors the NCPT and the EGSS programs to rapidly identify chipping clones and speed their commercial testing. Our breeding programs provide chipping candidates for evaluation in both trials with FL, NC, and NY serving as NCPT screening locations and NS serving as the initial EGSS screening site. Promising NCPT clones advance to the industry-funded SNaC trials where advanced chipping clones are tested for three years across 11 states. The most promising NCPT, SNaC, and NFPT clones are fast tracked into industry-funded seed propagation and commercialization trials. Clones developed by our four breeding programs are major components to these national, industry-driven efforts.
ME uses its own russet germplasm plus USDA-ARS-Idaho, CO, WI, and ND seedling tubers to develop russet types that are adapted to the Eastern. Yield, appearance, tuber length and size, specific gravity, internal quality, French fry color (from 7 and 10oC storage and reconditioned from 4oC storage), French fry texture, and disease reaction are used to further select the lines prior to NE-1231 and commercial evaluation. The most promising fry processing candidates are entered into the industry-funded NFPT which tests promising French fry clones at six locations (ME, WI, ND, ID, OR, WA). NFPT is used extensively by the large-scale national fry processors to identify candidate French fry processing varieties.
Molecular genetic research focused on improved chip and fry quality will be continued in this project. Recent genetic analyses have shown that alleles of vacuolar and apoplastic invertases are associated with cold-chipping ability in European germplasm (Draffehn et al. 2010). RNAi-mediated silencing of vacuolar invertase dramatically improves fry color (Bhaskar et al. 2010), suggesting that natural alleles with low expression are key to good fry color. Consistent with this, vacuolar invertase expression is very low in S. raphanifolium (Bhaskar et al. 2010). NY will characterize allelic variation of invertase genes to determine which alleles, including those previously introgressed from S. raphanifolium, are associated with good fry color. Assays to simplify tracking of desirable alleles will be developed to facilitate future breeding. An improved genetic base for long-term cold storage processing ability, including diploids from phu-stn, and hybrids with S. gourlayi has been developed by USDA-ARS. Crosses will continue and segregating families will be evaluated for ability to process after long-term storage.
1d. Improving the genetic base of fresh market and specialty potatoes. High-yielding, disease-resistant, fresh market lines will be intercrossed to produce seedling populations that will allow selection of superior fresh market varieties. Foremost among the selection attributes will be appearance (smooth skin texture, freedom from blemishes, and desirable color), tuber shape, yield, cooking quality (satisfactory texture, freedom from internal defects, after cooking darkening and sloughing), and pest resistance (see Objective #2).
Yellow-Fleshed Potatoes - USDA-ARS is developing yellow- and orange-flesh diploid potatoes for the ‘baby’ or creamer potato market. A primary objective is to lengthen tuber dormancy so they can be stored for several months without sprouting. Cooperators in FL and NM are participating in the early evaluations which will soon be expanded to include other NE1231 locations. All eastern breeding programs continue to include novel, yellow-fleshed clones in their crossing programs with the goal of developing yellow-fleshed potato varieties with improved market quality, pest resistance, and tolerance to environmental stress.
Red-, Purple-Skinned, and Other High-Value Novel-Colored Potatoes - The genetic base of red-skinned and other high-value, novel-colored potatoes will be improved through crosses and backcrosses between tetraploid and diploid lines with solid or patterned red or purple skin. Red- and purple-skinned clones will also be intercrossed with yellow-flesh clones to develop a population of colored-skin, yellow-flesh lines. Crosses will be made between tetraploid tuberosum and diploid phu-stn lines to add increased color variation and nutritional quality.
1e. Development of diploid inbred lines to facilitate breeding and genetic studies. In an initial survey of self-incompatibility phu-stn diploid population, 17/42 clones were found to be self-compatible. USDA-ARS will identify more self-compatible clones from this population and sequence candidate genes involved in self-incompatibility. Crosses among self-compatible clones will be undertaken to combine favorable gene combinations for development of elite inbred lines. The self-compatible clones from the phu-stn population will be subjected to haploid production by anther culture or genome elimination crosses to develop a doubled-monoploid population. While the offspring of most diploids are low yielding and produce small tubers, the offspring of a cross between inbred diploids S. chacoense clone M6 and US-W4 produce high yields of large tubers (Jansky et al. 2014). NY will evaluate whether these two clones can form the basis for two heterotic groups, introducing alleles for better appearance and tuber uniformity from diploid clones developed over the career of H. De Jong (AAFC Fredericton, now retired).
Objective 2: Use novel and improved potato germplasm to reduce the impact of economically important potato pests and abiotic stress in the Eastern US
2a. Improve potato resistance to significant pests in the East. Late Blight – Screening for late blight resistance within NE-1231 is conducted in the field and greenhouse using natural infection and/or artificial inoculation. The most promising late blight resistant selections undergo further evaluation in PA, the key late blight screening site for NE-1231. Recently developed late blight resistant populations include resistance derived from S. hougasii (Haynes and Qu, 2016) and S. bulbocastanum (ME). The population developed from S. hougasii (a 6x species) may potentially harbor chromosome dosage variants. Therefore, genomic fingerprinting via the SolCap SNP-chip or Illumina sequencing will be performed to assess dosage variation within this population. The goal is to identify stable late blight resistant clones for developing late blight resistant varieties. A diploid phu-stn late blight resistant population has been developed by USDA and PA. Representative 4x-2x crosses will be made to incorporate late blight resistance into tetraploid germplasm. An interbreeding seed nursery will also be established to generate seed which will be released to the breeding community as late blight resistant germplasm. A late blight resistant x susceptible cross has been made and a mapping population generated. This population will be phenotyped in the field in PA and genotyped using the potato SNP array (Neogen Corporation and Michigan State University). Genomic loci significantly associated with late blight resistance will be identified using Tetraploid Map Version 2. The SNPs identified from this work can be developed into molecular markers for future selection.
A tetraploid population was developed from clone, B0692-4, which has shown excellent to late blight resistance, crosses with a susceptible clone. Late blight resistance of this population will be evaluated in field trials in PA. The population will be evaluated for up to three years to ensure resistance stability. Clones from this population will be genotyped using the SNP array. SNPs linked to resistance in B0692-4 will be developed into molecular markers for future selection.
Scab resistant germplasm - Our breeding programs extensively utilize common scab resistant parent material and select for resistance in inoculated and/or naturally-infected field experiments. Clones are tested over multiple years because of environmental effects on disease incidence and severity. PA provides a centralized screening site for early-generation materials from USDA-ARS, while ME and NY conduct their own early-generation screening. Powdery scab resistant parents will also be identified and used in programs to improve resistance.
Dry rot, pink rot, and softrot resistant germplasm - Fusarium dry rot (Fusarium spp.), pink rot (Phytophthora erythroseptica) and soft rot (Pectobacterium and Dickeya spp.) resistance screening will be conducted using field (pink rot) or laboratory-based (soft rot and dry rot) techniques with the goal of identifying advanced clones and parents with improved resistance. Breeding populations will then be developed to allow further study of resistance and development of SNP-based markers.
Golden Nematode - Breeding efforts in NY have emphasized resistance to golden nematode Ro1; however, resistance to race Ro2 is also a priority. The NY program developed Ro2 resistance by selecting for adaptation within a collection of South American tetraploids and subsequent work has incorporated additional resistance sources from Europe to broaden the genetic base and provide resistance to G. pallida. Our other programs also use parental materials with nematode resistance. Progeny from crosses using resistant parents will be evaluated for resistance to both races of the golden nematode at the USDA-ARS in NY. Marker-assisted selection for golden nematode resistance (H1 marker; Galek et al. 2011) will be used to supplement traditional screening methods and provide earlier detection of resistant clones within selected breeding families. NY also has the ability to test for resistance to G. pallida in vitro.
Virus – All four breeding programs will continue to include virus-resistant clones as parents. Marker-assisted selection for potato virus Y resistance (Whitworth et al., 2009; Ryadg, RYSC3, Kasai et al., 2000; Rysto, YES3, Song and Schwarzfischer 2008) will be used to supplement traditional screening methods and provide earlier detection of resistant clones. We will attempt to clone the Ryadg gene using sequence capture followed by long-read sequencing to potentially provide a mechanistic understanding and additional molecular markers for this resistance trait.
Colorado Potato Beetle and Potato Leafhopper - NC has used the USDA-ARS-developed tetraploid S. chacoense (2n=4x=48) potatoes crossed with S. tuberosum (Sanford et al., 1997) to develop CPB resistant germplasm. During 2006-2014, NC used several of the most promising advanced chc-based CPB-resistant lines in crosses with NY’s S. tuberosum x S. berthaltii derived materials. The latter exhibit glandular-trichome-based insect resistance. Field evaluation of these materials will continue as part of the NE-1231 project.
2b. Improve the genetic base of potatoes for resistance to heat stress. Potato plants subjected to heat stress have lower tuber yield and quality (e.g. tubers may form in chains, have internal heat necrosis, and/or heat sprouting). Potato production in the south and mid-Atlantic states frequently experiences high temperatures during the late tuber bulking. USDA-ARS, NC and FL will screen the phu-stn population for heat tolerance by comparing tuber yield and quality traits from early-season and late-season plantings. Several wild diploid potatoes species with reported tolerance will be screened for heat tolerance by USDA-ARS. Tolerance will be measured as the ability to form tubers under elevated temperatures. Those lines found to be tolerant will be crossed with both heat-tolerant and heat-sensitive phu-stn to take advantage of phu-stn’s ability to tuberize under long-day conditions. The inheritance of heat tolerance will be determined.
2c. Improve the genetic base of potatoes for nitrogen uptake efficiency (NUE). Commercial potatoes currently take up only 33 to 53% of applied nitrogen. The rest is lost to denitrification and nitrate leaching. One strategy for improving NUE is to introgress high NUE traits from wild species. FL and USDA-ARS have identified improved NUE in chc and crosses have been made to transfer NUE into a phu-stn population. A mapping population has been generated between a phu-stn clone with poor NUE and a chc clone with superior NUE. This population will be phenotyped for NUE by measuring yield and quality traits at USDA-ARS (ME) and FL under high and low N regimes and genotyped using the potato SNP array. Loci and SNPs linked to NUE will be identified and used as markers for future breeding to improve NUE.
Objective 3. Evaluate yield, quality, and pest resistance of preliminary and advanced potato breeding lines in experimental- and commercial-scale trials at multiple Eastern locations to aid industry adoption of new varieties.
3a. Evaluation of Promising Selections for Early Maturity, Quality, and Storage Potential.
Seed Increase for Standardized Regional Variety Trials - Advanced selections will be placed in the NE-1231 Project seed nursery at the University of Maine Aroostook Research Farm in Presque Isle, ME to provide a uniform seed source for the project. The seed will be tested according to Maine seed certification regulations. This common seed source is a vital component for valid research and modeling of environmental characteristics, since performance of a clone varies widely according to the seed crop’s quality, growing, and storage conditions.
Regional Variety Trial Procedures - All tablestock, processing and specialty market selections will be evaluated in replicated field trials in multiple locations (FL, ME, NY, NC, OH, PA, VA) using standardized NE-1231 evaluation techniques and descriptors. These techniques include observations on agronomic as well as internal and external quality data. Bruise susceptibility (Hunter and Reeves 1983; Pavek et al. 1985), and storage characteristics will also be measured (ME). Appropriate industry standards (e.g. Atlantic, Snowden, Russet Burbank) are included at each test site. Five standard varieties will be grown at all NE-1231 test sites to provide data for modeling environments and genotype x environment interactions (USDA-ARS).
Processing from Storage - Samples of NE-1231 selections will be stored at two temperatures (typically 7.2 and 10C). Weight loss will be measured to help select clones that do not require the use of chemical sprout suppression. Chip or fry color will be measured with an Agtron instrument or with USDA Chip or Fry Color Charts following storage for two to six months (ME, NY, PA, USDA).
3b. Evaluate Promising Selections for Resistance to Potato Pests.
All breeding lines will be evaluated under uniform conditions for resistance/susceptibility to major potato diseases. This assessment provides comparative information to help breeding programs, researchers, and the industry decide on the merits of new clones. Regional disease screening will be conducted for golden nematode resistance (USDA-ARS NY), late and early blight (PA), common scab (ME), powdery scab (PA), potato virus Y – PVY (ME), potato leaf roll virus – PLRV (ME), and corky ring spot – CRS (FL). Additional disease resistance screening is done by the respective programs to screen their breeding materials for disease susceptibility including late and early blight (USDA-ARS, ME), common scab (USDA-ARS, ME, NY), powdery scab (ME), Verticillium wilt (ME), pink rot (ME), Fusarium dry rot (ME), bacterial soft rot (ME), potato virus Y – PVY (ME, NY), and potato leaf roll virus - PLRV (ME). To insure they do not mask symptoms, all selections not showing PVY or PLRV symptoms will be tested for pathogen presence using ELISA (ME).
3c. Evaluate promising selections for sensory and nutritional quality.
NE-1231 clones and advanced ME breeding clones will be evaluated for boiling and baking quality by consumer panels (ME). Test lines will be compared to appropriate industry standards. Only lines with acceptable total glycoalkaloid (TGA) content will be evaluated (Asano et al., 1996; Baker et al., 1991; Friedman and McDonald, 1997). A hedonic scale (Peryam and Pilgrim, 1957) will be used for each of the baked attributes. Sloughing and graying of boiled tubers will be subjectively evaluated using sensory panels. The boiled potato evaluations will employ a 15-point intensity scale. After cooking darkening of boiled selections will also be evaluated objectively using a LabScan XE Hunter Lab Colorimeter (Hunter Associates Laboratory, Reston, VA). Selected fresh market varieties will be compared using conventional stovetop steaming, microwave steaming and oven roasting conditions. Promising clones will be screened for phytochemical content (ME). Total phenolics will be measured (Velioglu et al., 1998). Chlorogenic acid and gallic acid will be used to generate standard curves. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant method will be used to assess antioxidant activity (Herald et al., 2012). Red, blue and purple potatoes will also be assayed for their total anthocyanin content (AOAC, 2005). All assays will be performed in triplicate. Ascorbic and dehydroascorbic acid (vitamin C) will be determined by high performance liquid chromatography (HPLC) using a recently developed method (Hutt, 2015). Potassium content will be determined on 4 to 6 promising clones and compared to established standard varieties.
3d. Study cultural practices that optimize the performance of new potato clones and develop more sustainable agricultural systems. Optimized cultural practices need to be developed for new potato clones to increase the likelihood of commercial success. Cultural practice experiments will be performed to determine optimal management practices for new clones (FL, ME, NC, NY, OH, PA, VA). These studies typically include optimizing fertilization, harvest date, irrigation, plant spacing and other cultural practices.
Objective 4. Provide timely and relevant information to stakeholders through various means including the maintenance of a project website and a web-based potato variety performance database for use by researchers, extension, potato growers, and allied industry members.
Project cooperators will present project information to stakeholders through presentations, printed media, trade shows, and websites to inform them of promising selections and new variety releases. A long-term database for NE-1231 trials has been established to facilitate the data analysis and encourage collaboration among NE-1231 participants. Web interfaces to this database allow access for all project participants and are updated and improved as needed and new ideas emerge. The website also provides potato production information and project results in an interactive, searchable potato variety trial database designed to provide access to the results of the trials coordinated through the Eastern potato variety development project.
Measurement of Progress and Results
- Potato families that segregate for key quality, stress resistance, and pest tolerance traits will be developed and used to improve genome wide, marker-based selection strategies for key quality, stress tolerance, and pest resistance traits.
- The germplasm pool of high specific gravity, stress tolerant, disease-resistant, insect-resistant and/or nutritionally-enhanced clones available for breeding purposes in the US will be broadened.
- Our collective potato breeding efforts will result in new varieties, such as Lamoka, with favorable characteristics for chip, fry processing, and/or fresh market utilization.
- Potato breeders and allied scientists effectively communicate research results through meetings, websites, and published reports and will design improved regional breeding and selection strategies to more efficiently develop varieties for adaption to specific production areas as well as wide geographic areas.
- A project website and a web-based potato variety performance database for use by researchers, Extension, potato growers, and allied industry members will be refined, updated, and maintained to facilitate communication, information exchange and data analysis.
Outcomes or Projected Impacts
- New potato varieties with improved disease and insect resistance, resistance to IHN, improved processing or fresh market characteristics, and enhanced nutritional quality will be commercially evaluated and released, providing growers with better marketing opportunities, great profits, and/or improved resistance to pests.
- Farmers will learn how to successfully grow newly released potato varieties in different climates and for different uses.
- Adoption of new, high quality, pest resistant varieties will be more rapid, leading to increased profitability, greater worker safety, improved human diet, and reduced pesticide load.
- Strengthened communication and interactions among potato scientists located in the eastern U.S. and elsewhere will lead to greater productivity and collaboration.
- Web-based and traditional conduits for the distribution of timely and readily available potato variety production information to growers, allied industry members and consumers will be further developed and strengthened.
- Rural communities dependent upon Eastern potato production will benefit from the economic and environmental sustainability provided by adoption of improved new varieties.
Milestones(2018):Incorporate disease and insect resistances, abiotic stress resistances, improved processing characteristics, and enhanced nutritional quality, from diverse diploid and tetraploid potato species into high quality, adapted germplasm (S. tuberosum)
(2018):Develop potato families that segregate for key quality, stress resistance, and pest tolerance traits and use them to improve marker-based selection strategies for key quality, stress tolerance, and pest resistance traits
(2018):Crosses and backcrosses made between tetraploid TBR and diploid PHU-STN lines with solid or patterned red or purple skin to increase color variation in regionally adapted clones and selections made
(2018):Improve our interactive and searchable potato variety trial database implemented in response to user feedback
Projected ParticipationView Appendix E: Participation
The NE-1231 Regional Potato Variety Development Project currently conducts outreach activities in all participating states using techniques ranging from face-to-face presentations at grower and scientific meetings to providing web-based content for industry members and consumers. Typical outreach activities include:
- Publication of project results in the NE-1231 annual publication, scientific journals, etc.
- Development of applied publications and Extension materials targeted to growers in each participating state or province.
- Multiple formal and informal presentations, demonstrations, trade show booths, and field days targeted to growers and industry in each participating state or province.
- Providing web-based project information via the NE-1231 project website to enhance access to research results, variety profiles, variety summaries, and photographs (http://potatoes.ncsu.edu/NE.html).
ORGANIZATION AND GOVERNANCE
The regional technical committee is composed of all participating cooperators (see Appendix E), an administrative advisor (currently Dr. Fred Servello) appointed by the Northeast Agricultural Experiment Station Directors, and a NIFA Representative (Dr. Ann Marie Thro). The technical committee meets at least once each year to discuss progress of the research, review procedures, coordinate research and plan future research activities.
The regional technical committee will elect an executive committee composed of a chair, vice-chair, and secretary. A succession of officers will be maintained so that the vice-chair becomes chair, the secretary becomes vice-chair, and a new secretary is elected each year. The responsibilities of the executive committee members are as outlined in the Guidelines for Multistate Research Activities. The chair will preside at all meetings of the technical committee and is responsible for organizing the agenda of the annual meeting. The vice-chair will prepare the annual report for the project. The secretary will prepare the minutes of the annual meeting and any special meetings. The administrative advisor is responsible for distributing the minutes and submitting the annual report and minutes to the NIFA representative and other interested parties. Participation by Agriculture Canada, the Provinces of Quebec and New Brunswick, Maine Department of Agriculture, Cooperative Extension, and Industry representatives is at the invitation of the Technical Committee with the approval of the Administrative Advisor.
AOAC International. 2000. Official Methods of Analysis, 17th ed.
AOAC International. 2005. Official methods of analysis of AOAC International. W. Horwitz, editor; G.W. Latimer, assistant editor. Gaithersburg, MD.
Asano, M., N. Goto, and K. Isshiki. 1996. J. Jpn. Soc. Food Sci. Technol. 43:593-597.
Baker, D.C., R.F. Keeler, and W. Gaffield. 1991. Toxicosis from steroidal alkaloids of Solanum species. In: Handbook of Natural Toxins, Keeler, R.F., Ed., Marcel Dekker, New York, Vol 6., 71-82.
Banjongsinsiri, P. 1999. The influence of potato cultivar and chemical treatment on the development of a pre-peeled, refrigerated product. M.S. Thesis, University of Maine, 104 pp.
Bhaskar, P.B, L. Wu, J.S. Busse, B.R. Whitty, A.J. Hamernik, S.H. Jansky, C.R. Buell, P.C. Bethke, and J. Jiang. 2010. Suppression of the vacuolar invertase gene prevents cold-induced sweetening in potato. Plant Physiology 154, 939-948.
Bonierbale, M.W., R.L. Plaisted and S. Tanksley. 1992. Genetic mapping and utilization of quantitative trichome-mediated insect resistance in potato. Neth. J. Pl. Path. 98 Supplement 2:211-214.
Bonierbale, M.W., R.L. Plaisted, O. Pineda and S.D. Tanksley. 1994. QTL analysis of trichome-mediated insect resistance in potato. Theor. Appl. Genet. 87:973-987.
Brown C.R., R.W. Durst, R. Wrolstad, and W. De Jong (2008) Variability of Phytonutrient Content of Potato In Relation to Growing Location and Cooking Method. Potato Research 51: 259-270
Bushway, R.J. 1986. Determination of a- and P-carotene in some raw fruits and vegetables by
high-performance chromatography. J. Agr. Food Chem. 34:409-412.
Cao, G. E. Sofic, and R.L. Prior. 1996. Antioxidant capacity of tea and common vegetables. J. Agr. Food Chem. 44:3426-3431.
Draffehn, A.M., S. Meller, L. Li, and C. Gebhardt. 2010. Natural diversity of potato (Solanum tuberosum) invertases. BMC Plant Biology 10:271
Friedman, M., and G.M. McDonald. 1997. Potato glycoalkaloids: Chemistry, analysis, safety and plant physiology. Crit. Rev. Plant Sci. 16:55-132.
Galek, R. M. Rurek, W.S. De Jong, G. Pietkiewicz, and H. Augustyniak. 2011. Application of DNA markers linked to the potato H1 gene conferring resistance to pathotype Ro1 of Globodera rostochiensis. J. Applied Genetics 52:407-411.
Gauch, H.G. Jr. 2006. Statistical Analysis of Yield Trials by AMMI and GGE. Crop Sci. 46:1488-1500.
Genstat 5 release 3 Reference Manual. 1993. Chapter 10: REML estimation of variance components and analysis of unbalanced designs. Pp. 539-584.
Jansky, S.H., Y. S. Chung and P. Kittipadukal. 2014. M6: A Diploid Potato Inbred Line for Use in Breeding and Genetics Research. Journal of Plant Registrations doi:10.3198/jpr2013.05.0024crg
Hanneman, R.E., Jr. 1993. Ability of wild and cultivated potato species to chip directly from 2C storage. Am. Potato J. 70:814.
Haynes, K.G. 2000. Inheritance of yellow-flesh intensity in diploid potatoes. J. Amer. Soc. Hort. Sci. 125:63-65.
Haynes, K.G., W.E. Potts, J.L. Chittams and D.L. Fleck. 1994. Determining yellow-flesh intensity in potatoes. J. Am. Soc. Hort. Sci. 119:1057-1059.
Haynes, K.G., B.A. Clevidence, D.D. Rao, and B.T. Vinyard. 2011. Inheritance of Carotenoid Content in Tetraploid and Diploid Potato clones. Journal of the American Society for Horticultural Science. 136:265-272.
Haynes, K.G., J.B. Sieczka, M.R. Henninger and D.L. Flock. 1996. Clone x environment interactions for yellow-flesh intensity in tetraploid potatoes. J Am Soc Hort Sci
Haynes, K.G., D.R. Wilson and M.S. Kang. 1995. Genotype x environment interactions for specific gravity in diploid potatoes. Crop Sci 35:977-981.
Henninger, M. R., J. W. Patterson, and R.E. Webb. 1979. Tuber necrosis in Atlantic. Amer. Potato J. 56:464.
Henninger, M.R., S.B. Sterrett and K.G. Haynes. 2000. Broad-sense heritability and stability of internal heat necrosis and specific gravity in tetraploid potatoes. Crop Science. 40:977-984.
Hill, J. 1975. Genotype-environment interactions -- a challenge for plant breeding. J. Agr. Sci. 85:477-493.
Horgan, G.W. and E.A. Hunter. 1992. Introduction to REML for scientists. 59pp. Univ. of Edinburgh.
Hunter, J.H. and A.F. Reeves. 1983. Respiration increase as an objective measurement of relative susceptibility to bruise damage in breeding clones. Am Potato J 60:811(abst.).
Jensen, K., M.A. Peterson, L. Poll, and P.B. Brockhoff. 1999. Influence of cultivar and growing location on the development of flavor in precooked vacuum-packed potatoes. J. Agric. Food Chem. 47:1145-1149.
Kasai, K. Y., V.A. Morikawa, J.P.T. Valkonen, C. Gebhardt, and K.N. Watanabe. 2000. Development of SCAR markers to the PVY resistance gene RYadg based on a common feature of plant disease resistance genes. Genome 43:1-8.
Lu, W., K. Haynes, E. Wiley, and B. Clevidence. 2001. Carotenoid content and color in diploid potatoes. J. Amer. Soc. Hort Sci. 126:722-726.
McCord, P.H., B.R. Sosinski, K.G. Haynes, M.E. Clough, and G.C. Yencho. 2011. Linkage mapping and QTL analysis of agronomic traits in tetraploid potato (Solanum tuberosum L. subsp. tuberosum). Crop Science. 51: 771-785.
McCord, P.H., B.R. Sosinski, K.G. Haynes, M.E. Clough, and G.C. Yencho. 2011. QTL mapping of internal heat necrosis (IHN) in tetraploid potato. Theoretical and Applied Genetics. Theor Appl Genet 122:129–142.
Meilgaard, M.C., G.V. Civille, and B.T. Carr. 2007. Sensory Evaluation Techniques. Taylor & Francis, Boca Raton, FL.
National Potato Council. 2009. Potato statistical yearbook, 2009. NPC, Washington, DC, 80pp.
Oruna-Concha, M.J., S. C. Duckham, and J. M. Ames. 2001. Comparison of volatile compounds isolated from the skin and flesh of four potato cultivars after baking. J. Agric. Food Chem. 49:2414-2421.
Pavek, J., D. Corsini, and F. Nissley. 1985. A rapid method for determining blackspot susceptibility of potato clones. Am Potato J 62:511-517.
Plaisted, R.L., W.M Tingey and J.C. Steffens. 1992. The germplasm release of NYL235-4, a clone with resistance to the Colorado potato beetle. Am. Potato J. 69:843-846.
Planning Decisions, Inc. 2003. A study of the Maine Potato Industry, its economic impact. S. Portland, ME, 36 pp.
Sanford, R.S. Kobayashi, K.L. Deahl, and S.L. Sinden. 1997. Diploid and tetraploid Solanum chacoense genotypes that synthesize leptine glycoalkaloids and deter feeding by Colorado potato beetle. Am Pot J 74:15‑21.
Santa Cruz, J., K.G. Haynes, and B.J. Christ. 2009. Effects of one cycle of recurrent selection for early blight resistance in a diploid hybrid solanum phureja-S. stenotomum population. American Journal of Potato Research. 86:490-498.
Sapers, G.M and R.L. Miller. 1993. Control of enzymatic browning in pre-peeled potatoes by surface digestion. J. Food Sci. 58:1076.
Simonne, A.H., S.J. Kays, P.E. Koehler, and R.R. Eitenmiller. 1993. Assessment of beta-carotene content in sweetpotato (Ipomoea batatas Lam.) breeding lines in relation to dietary requirements. J. Food Compos. Anal. 6:336-345.
Simonne, A.H., E.H. Simonne, R.R. Eitenmiller, H.A. Mills and C.P. Cresman, III. 1997a. Could the Dumas method replace the kjeldahl digestion for nitrogen and crude protein determination in foods?. J. Sci. Food Agr.73:39-45.
Simonne, A. H., E. H. Simonne, R.R. Eitenmiller, H.A. Mills, and N.R. Green. 1997b. Ascorbic acid and provitamin A contents of unusual colored bell peppers (Capsicum annuum L.). J. Food Comp. Anal. 10:299-311.
Simonne, A.H., T.-S. Huang, and C.I. Wei. 2001. Cooking time unequally affects carotenoids in different vegetables. Paper presented at the 2001 Annual IFT meeting, NewOrleans, LA.
Sinden, S.L., L.L. Sanford, and K.L. Deahl. 1986. Segregation of leptine glycoalkaloids in Solanum chacoense Bitter. J Agric Food Chem 34:372-377.
Souza, E., J.R. Myers and B.T.Scully. 1993. Genotype by environment interaction in crop improvement. In: Crop Improvement for Sustainable Agriculture. Edited by M.B. Callaway and C.A. Francis. University of Nebraska Press. pp. 192-233.
Sterrett S.B. and M.R. Henninger. 1997. Internal heat necrosis in the mid-Atlantic region—influence of environment and cultural management. Am Potato J 74:233-243.
Sterrett, S.B., M.R. Henninger, G.C. Yencho, W. Lu, B.T. Vinyard, and K.G. Haynes. 2003. Stability of internal heat necrosis in tetraploid x diploid potatoes. Crop Science43: 790-796.
Tai, G.C.C., T.R. Tarn, G.A. Porter and S.B. Sterrett. 1993. Performance evaluations of varieties and selections in the Northeastern regions of North America. Amer. Potato J. 70:685-698.
Ulrich, D., E. Hoberg, W. Neugebauer, H. Tiemann, and U. Darsow. 2000. Investigation of the boiled potato flavor by human sensory and instrumental methods. Am. J. Potato Res. 77:111-117.
USDA National Agricultural Statistics Service. 2009. Potato Production Statistics.
Vainionopaa, J., R. Kervinen, M. de Pardo, E. Laurila, M. Kari, L. Mustonen, and R. Ahvenainen. 2000. Exploration of storage and process tolerance of different potato cultivars using principal component and canonical correlation analyses. J. Food Eng. 44:47-61.
Weber, D.C. and D.N. Ferro. 1994. Colorado potato beetle: diverse life history poses challenge to management. In: G.W. Zehnder, R.K. Jansson, M.L. Powelson, and K.V. Raman (eds.). Advances in Potato Pest Biology and Management. APS Press, St. Paul, MN.
Yencho, G.C., Kowalski, S.P., Kennedy, G.G., and Sanford, L.L. 2000. Inheritance of leptine glycoalkaloids and resistance to Colorado potato beetle (Leptinotarsa decemlineata Say) in F2 Solanum tuberosum (4x) X S. chacoense (4x) potato progenies. Am. J. Potato Res. 77: 167‑178.
Yencho, G.C., P.H. McCord, K.G. Haynes, and S.B. Sterrett. 2008. Internal heat necrosis of potato – a review. Am. J. Potato Research. 85:69–76.
Zobel, R.W., M.J. Wright and H.G. Gauch, Jr. 1988. Statistical analysis of a yield trial. Agron. J. 80:388-393.