X. ATTACHMENT A

ATTACHMENT A. RELATED, CURRENT, AND PREVIOUS WORK (DETAILS)

The first two sections of this proposal ISSUES AND JUSTIFICATION and RELATED, CURRENT, AND PREVIOUS WORK describe several key industry needs that can be addressed by this project and briefly describe the current status of research activity directed toward these needs. The following sections provide a more detailed summary of current and related work.

Fresh Market Cultivars. Several selections from the eastern U.S. have either been released or are in the later stages of evaluation for their potential for the round, white-skinned tablestock market. Allegany (Plaisted et al., 1993), Eva (Plaisted et al., 2001), Mainestay (Reeves et al., 1998), Portage (Reeves et al., 1995), Prestile (Reeves et al., 1994), St. Johns (Reeves et al., 1996), Quaggy Joe (Reeves et al., 2000), and Reba (Plaisted et al., 1999) have all been officially released as tablestock cultivars in the past 10 years. Reba, a recent New York release, provides high yields of early-sizing, large tubers. It also chips well, although specific gravity tends to be low in some environments. It is resistant to race Ro1 of the golden nematode. There were 605 acres of seed produced in Maine in 2001. Eva, another recent New York release, produces very attractive tubers with bright skin and shallow eyes. It is resistant to race Ro1 of the golden nematode and potato viruses X and Y. There were 130 acres of seed produced in Maine during 2001. Mainestay has enjoyed some success as a high yielding fresh market round white. It peaked at number six in certified acreage in Maine during 1995; however, acreage declined due to a shrinking fresh market industry in Maine and because it sometimes develops a purple discoloration in the tuber flesh. Quaggy Joe is medium-late maturing, high-yielding selection which has received some commercial interest. It stores well, rates well in taste panel tests, and has a high proportion of marketable tubers. While these recent releases offer some advantages to eastern growers, additional new varieties are needed which overcome the limitations present in current fresh market cultivars. Growers need high yields and they need a high percentage of marketable tubers (appropriate size distribution, freedom from external and internal defects, and good storability). Appearance of the washed tubers needs to be improved to strengthen the position of eastern potatoes in the market place. This requires breeding and selection of new varieties which produce bright, attractive tubers under eastern conditions and are resistant to cosmetic tuber diseases (e.g. scab, silver scurf, black scurf, etc.).

New potato varieties for fresh market need to emphasize excellent cooking quality. Attractive, distinctive tuber appearance combined with excellent cooking quality may allow variety differentiation and a competitive edge in marketing. The flavor, texture, and color of baked, boiled and fried potatoes varies among varieties. The chemical components that combine to form the unique flavor of potatoes have been well studied and documented in the literature (Coleman and Ho, 1980; Ho and Coleman, 1980); however, the qualitative flavor factors have not. Recently, research has been published comparing the volatile compounds isolated from the skin and flesh of baked potatoes (Oruna-Concha et al., 2001). Studies have also examined the flavor and sensory components of cooked potatoes in different varieties (Jensen et al., 1999; Ulrich, et al., 2000; Vainionopaa et al., 2000; Ereifi et al., 1997). Sinden et al. (1976) used the flavor profile method to establish a relationship between the flavor of potatoes and their glycoalkaloid and total phenolic contents. Other researchers have investigated various instrumental methods (Davis and Leung, 1987; McComber et al., 1998; Thybo and Martens, 1999) for evaluating the textural characteristics of cooked potatoes as a substitute for sensory evaluation. In all instances, these methods could not effectively substitute for sensory attributes.

Selection of new varieties should also consider nutritional attributes. Conservative estimates show that 90% of the vitamin C in the U.S. diet is supplied by fruits and vegetables including potato (Goddard and Matthews, 1979). Potatoes are naturally rich in vitamin C (ascorbic acid) and they account for the largest share of fresh vegetable consumption in the U.S. (Pollack, 2001). Total carotenoid content of yellow-fleshed diploid phu-stn clones ranged from 4 to 22 times that found in the tetraploid white-fleshed cultivar 'Superior' and 3 to 13 times that found in the yellow-fleshed cultivar 'Yukon Gold' (Lu, et al., 2001). This germplasm could be useful in improving the carotenoid nutritional components of cultivated potato. Increasing tuber concentrations of nutrients such as provitamin A, carotenoid, or phytonutrients would be highly beneficial to human health.

Chipping Cultivars. Atlantic is the highest dry matter chipping cultivar grown on a commercial scale in the NE-184 region and all recently released high dry matter cultivars are genetically related to Atlantic (Haynes et al., 1995). However, Atlantic tubers are very susceptible to internal heat necrosis. Since processors demand high dry matter potatoes, it is necessary to determine the feasibility of developing high dry matter potato populations without susceptibility to internal heat necrosis. NE-184 research (Henninger et al., 2000) has demonstrated that the incidence of internal heat necrosis (IHN) is largely a function of genotype with broad-sense heritability estimated to be 0.83 to 0.88. Henninger et. al. (2000) found no significant correlation between susceptibility to IHN and either total yield or specific gravity. Stable, high specific gravity clones with good chip color and low IHN incidence have been developed in a diploid hybrid population of S. phureja x S. stenotomum (phu-stn)(Haynes et al., 1995; Sterrett et al., 2002) . This work indicates that phu-stn hybrids can be used to expand the genetic base for chipping potatoes and reduce IHN problems for growers.

Much of the Northeast potato crop is placed in storage and marketed during the fall and winter months. Sprout growth and weight loss in potatoes are reduced by low temperature storage; however, such storage conditions result in sugar accumulation and unacceptable processing quality in currently available processing cultivars. Consequently, processing cultivars are currently treated with sprout inhibiting chemicals and stored under warm conditions. Growers often apply sprout inhibitors to maintain tuber quality in storage for those cultivars that sprout

early and rapidly lose quality when not treated. Development of new cultivars with long dormancy during low temperature storage would reduce the need for sprout inhibitors and allow

growers to maintain tuber quality without chemical use. Progress has been made in the development of cold temperature chipping cultivars in the East, namely, MaineChip (Reeves et al., 1994), AC Novachip (DeJong et al., 1995), Pike (Plaisted et al., 1998), and Andover (Plaisted et al., 1998). Pike is a high gravity chipping clone with excellent scab resistance and resistance against race Ro1 of the golden nematode. There were 201 acres of seed produced in Maine during 2001. Andover is an early maturing line that produces very nice chips from cold storage, but yields are not as high as Atlantic. It is resistant to race Ro1 of the golden nematode. There were 397 acres of seed produced in Maine during 2001. Several other advanced chipping lines in the NE-184 program may be released in the coming year. They include NY112, NY102, B0564- 8, and B0766-3. Of these, NY112 is the highest yielding. It produces acceptable chips and has consistently yielded more than Atlantic. It will likely be named and released as a new variety during 2002 or 2003. However, new cultivars that will process after even longer periods of cold storage are needed. Thus, new genetic sources of long-term, cold storage chipping ability must be exploited. Two diploid potato species reportedly have long-term cold storage chipping ability: S. tuberosum Group phureja and S. raphanifolium (Hanneman, 1993). Seedlings from crosses between haploid-species (can. and phu.) hybrids obtained from Dr. Robert Hanneman's USDA-ARS program and the Beltsville S. phureja-S. stenotomun population are being grown in the field and evaluated for processing potential. Diploid potatoes from S. raphanifolium and phu-stn have been produced that have potential to produce chips of acceptable color following long-term storage at 5oC. Selection for clones which maintain processing quality during cool temperature storage is currently underway and is a viable approach towards reducing sprout inhibitor use by potato producers. Energy consumption associated with warm temperature storage of chipping potatoes would also be reduced.

Russet-Skinned Cultivars. Amey (Haynes et al., 2001) is a russet-skinned cultivar which was been extensively tested in the NE-184 project. It offered several advantages for eastern growing conditions including resistance to common scab, verticillium wilt and race Ro1 of the golden nematode. It could be marketed either for fresh market or for processing into french fries; however, it thus far has met with little success as a commercial variety. AF1753-16 is currently generating considerable interest in Maine. It is likely to be useful for french fry processing. It sizes early and produces good quality fries, but does not consistently produce attractive tubers for fresh market. It is high yielding, resistant to verticillium wilt, and stress tolerant.

Specialty Cultivars. The consumer acceptance of and willingness to pay a premium price for the yellow-flesh cultivar 'Yukon Gold' has resulted in renewed emphasis in breeding programs for developing new yellow-flesh cultivars. Keuka Gold was released by Cornell University during 1999 in response to this increasing interest. It is a very high yielding, pale-yellow-fleshed clone. Although it performs well in upstate NY and Maine, NE-184 trials revealed a susceptibility to heat necrosis, precluding its utilization in more Southern environments. There were 18 acres of seed produced in NY during 2001. Methods of sampling for yellow-flesh intensity have been identified to reduce labor costs associated with selection while preserving the statistical sensitivity of the tests (Haynes et al., 1994). In addition, the influence of genotype x environment interactions on yellow-flesh intensity of tetraploid clonal selections is very small, indicating that selecting for yellow-flesh intensity can be done in one location (Haynes et al., 1996). Yellow-flesh intensity is highly heritable in the diploid hybrid phu-stn population, indicating that the development of very intense yellow-flesh in this population will be easy (K.G. Haynes, personal communication).

Work continues toward identifying the carotenoid composition of yellow-fleshed, diploid clones. Total carotenoid content of yellow-flesh, diploid potatoes from phu-stn ranges from 5 - 10 times that found in tetraploid white-flesh potatoes and 1.5 - 4 times that found in yellow-flesh potatoes (K.G. Haynes, personal communication). Thus, the yellow-flesh diploids are a source of new germplasm for improving yellow-flesh intensity and carotenoid content in tetraploid potatoes. Yellow-fleshed diploid potatoes from a hybrid population of phu-stn need to be outcrossed to tetraploid yellow-flesh selections from S. tuberosum to further enhance the carotenoid composition of cultivated potatoes in the East.

Heavy tuber netting develops in most red-skinned selections grown in the East and this netting severely limits their marketability. Redsen, which is one cultivar which does not have this problem, has not gained commercial acceptance because it skins easily during harvest and suffers from seed piece decay problems. NorDonna has attracted considerable recent attention in the eastern U.S. because of its very attractive skin. However, all red-skinned cultivars currently available are susceptible to silver scurf, which is a serious tuber surface blemish. Several promising red-skinned lines from the USDA-ARS program are currently being evaluated for possible utility in the eastern U.S.

Crosses between S.tuberosum red-skinned cultivars and S. tuberosum x phu-stn red-skinned hybrids are being made and segregating progeny are being evaluated for red-skin intensity, tuber conformation and appearance, and susceptibility to silver scurf. In addition, these red-skinned phu-stn hybrids will be intercrossed with the yellow-flesh phu-stn hybrids to develop a population of red-skinned, yellow-flesh diploids with superior tuber conformation for specialty "B" markets and for use in future 4x-2x crosses.

Colorado potato beetle. A population with resistance to the Colorado potato beetle (CPB) has been developed utilizing Solanum berthaultii (Bonierbale et al., 1992; Bonierbale et al., 1994). The clone NYL235-4, which has good resistance to CPB along with acceptable tuber conformation, has been released as germplasm to other breeders working on resistance to the CPB (Plaisted et al., 1992). One Maine seed producer currently sells seed of NYL235-4 under the name of "Prince Hairy" to organic growers. Superior CPB resistant selections continue to be backcrossed to S. tuberosum to incorporate CPB resistance into a more horticulturally acceptable form. The most advanced CPB resistant clone is currently NYT88-19. Its produces reasonably attractive tubers and exhibits only a small yield reduction when grown without insecticide sprays.

All current CPB resistant lines are derived from a handful of crosses between tetraploid S. tuberosum and unreduced pollen from diploid S. berthaultii. There have been limitations in the existing populations that should be eliminated by selecting for favorable traits at the 2x level for several generations prior to making 4x-2x crosses. Another CPB resistance approach is to enhance gene expression for leptine biosynthesis, a potent class of glycoakaloids from S. chacoense (Sinden et al., 1986; Sanford et al., 1997; Yencho et al., 2000). Leptines are potentially advantageous because they are present only in foliage and are not expressed in tubers. When the trichome-based and leptine-based resistance selection has progressed sufficiently it should be possible to merge these valuable resistance traits into common germplasm and work toward including these traits into commercial cultivars.

Late blight. R-gene (race-specific) resistance, generally derived from Solanum demissum has been used for late blight control for nearly a century (Forbes et al., 1994). The pathogen population rapidly generates strains that overcome specific genes, and race-specific resistance has largely been abandoned. Genome mapping of R genes is progressing (El-Kharbotly et al., 1994; Leonard-Schippers et al., 1994; Meksem et al., 1995) but their practical use is unlikely unless many cloned genes are included in a pyramiding scheme. Two of the breeding programs associated with the NE-184 project have had long-term breeding efforts for resistance to late blight. In 1966, Cornell University initiated a project developing a tetraploid S. andigena and S. vernei population for adaptation and late blight resistance (R.L. Plaisted, personal communication). NY121 is currently the most advanced product resulting from this selection effort. Over the past six years it has exhibited excellent field resistance to several different races of late blight. NY121 is also resistant to both races Ro1 and Ro2 of the golden nematode, potato virus Y, and scab. Blight-resistant parents from Poland and the UK are also being used to broaden the base of resistance in Cornell germplasm, some highly resistant progeny are now at intermediate stages of selection for agronomic performance. In 1976 the USDA program initiated a breeding effort for late blight resistance using S. demissum germplasm (Goth et al., 1994). Two blight resistant selections from this population have been released as germplasm to other breeders (Goth and Haynes, 1996). In addition, initial screening of an adapted, hybrid diploid phu-stn population, which has also undergone more than ten cycles of recurrent selection for adaptation, suggests that it also has good resistance to late blight and that this resistance is provided by polygenic, rather than race-specific traits (Haynes and Christ, 1999). These late blight resistance sources will over time be developed into varieties with durable resistance.

Multiple genetic sources of resistance to late blight have been assembled by the USDA, Maine and New York potato breeding programs. Parental materials with both vertical and horizontal resistance to late blight are being used in these breeding programs. Sources of resistance include material from the International Potato Center, Europe, India, and an S. andigena-S. vernei population developed at Cornell. Segregating populations are being used to enhance the understanding of inheritance at the molecular level. Molecular markers for late blight resistance are being developed (Costanzo, et al., 2000; Liu et al., 1998a, 1998b; 1999).

Because fungicides have been available for suppression of late blight, and because quantitiative transfer of polygenic horizontal resistance is difficult, late blight resistance has seldom been a prime potato breeding objective in developed countries. With mounting concerns about the safety, expense, and ultimate reliability of fungicides in the face of increasingly virulent Phytophthora strains, horizontal resistance is now seen as the most appropriate long-term strategy for improved late blight control.

Early blight. Simulation models indicate that the replacement of a susceptible cultivar with one having moderate resistance to early blight would allow a 50% reduction in the amount of fungicide required to suppress the disease; however, most current cultivars are quite susceptible. Castile (Halseth et al., 1991), one of the cultivars developed and tested through the NE-184 project has moderate levels of resistance to early blight, such that fewer fungicide sprays need be applied during the growing season (Stevenson, 1994). Higher levels of resistance are still necessary to further reduce fungicide application. Resistance to early blight in the phu-stn population is highly heritable (Herriott et al., 1986; Ortiz et al., 1993). These diploids have been used in 4x-2x crosses with S. tuberosum germplasm and the resultant progenies also had good levels of resistance to early blight (Herriott et al., 1990). Early blight resistant progenies from these 4x-2x crosses have been backcrossed to S. tuberosum to improve tuber conformation.

Resistance to early blight, caused by Alternaria solani, has been identified in diploid potatoes and transferred into the tetraploid germplasm base via 4x-2x crosses (Herriott et al., 1990). Molecular markers for early blight resistance in a diploid phu-stn F1 population are being developed (Zhang, 2000).

Common scab. The physiological/anatomical basis for scab resistance and its inheritance are not well understood. Scab evaluation is normally done for advanced selections under field conditions. Recently, rating techniques have been expanded to allow selections to be clustered on the basis of the type of scab lesion and the amount of tuber surface area infected (Goth et al., 1993). Genetic variation in S. tuberosum accounted for most of the observed variation for scab reaction as measured by either the type of lesion or the amount of surface area covered (K.G. Haynes, personal communication). Genotype x environment interactions were quite low, which may be due to the fact that all four environments were extremely conducive to scab development. A technique that would allow earlier, more uniform screening of breeding lines is desirable. One possibility is the use of the pathogen's toxin, thaxtomin, to screen minitubers (Loria, 1994). In the Cornell breeding program all clones are subjected to intensive field scab resistance testing from the fourth year of selection onwards. The recently released NY variety Pike (Plaisted et al., 1998) has been successful in midwestern states in large part because it is more resistant to scab than the industry-standard storage chipping variety, Snowden.

Crosses in all three eastern potato breeding programs have resulted in segregating populations with varying levels of scab resistance. The NE-184 project will provide information on the inheritance of scab resistance in diploid phu-stn populations. These populations have already been generated and will be evaluated for scab resistance.

Bacterial Ring Rot. Bacterial ring rot (BRR) is caused by Corynebacterium michiganense subsp. sepedonicus. It is a disease that is currently controlled by inspection and regulation rather than by resistance or tolerance. Detection occurs during foliage inspections at seed farms prior to vine desiccation and, to a lesser extent, during subsequent tuber inspections. Adequate symptom expression is essential for detection, but field symptoms can vary due to environmental conditions, disease severity, and cultivar (Gudmestad, 1994; Kurowski and Manzer, 1992; Westra et al., 1994). Very tolerant cultivars fail to show any symptoms despite high vascular titers of the bacterium and this inoculum source could spread to sensitive varieties with devastating consequences (Manzer and Kurowski, 1992). Therefore, all promising breeding selections must be screened for BRR symptom expression.

Rhizoctonia. Rhizoctonia disease, caused primarily by Rhizoctonia solani AG3, is a serious diseases of potatoes because of its endemic and ubiquitous presence. Marketable yield losses of up to 30% are often cited, although losses of 10 - 15% are more common (Carling et al., 1989; Little et al., 1988). Resistance to this disease is not present in currently available cultivars; however, screening programs within NE-184 may help select advanced lines which have improved tolerance to this disease.

Golden nematode. Several potato cultivars with resistance to the Ro1 race of the golden nematode (Globodera rostochiensis) were originally tested in the NE-184 Project and are available from foundation seed growers: Allegany (Plaisted et al., 1993), Andover (Plaisted et al., 1998a), Castile (Halseth et al., 1991), Elba (Thurston et al., 1985), Eva (Plaisted et al., 2001), Genesee (Plaisted et al., 1993), Hampton (Plaisted et al., 1985), Kanona (Plaisted et al., 1989), Pike (Plaisted et al., 1998b), Reba (Plaisted et al., 1999) and Steuben (Plaisted et al., 1991). Of these, Pike and Reba have received the widest acceptance. Pike is widely grown in the Midwest with almost 2000 acres of seed produced nationally in 1999. Eva is a very attractive tablestock potato, although it will still be a few years until its level of widespread acceptance can be determined.

Recently, a new race (Ro2) of golden nematode was reported in New York (Brodie, 1995; Brodie, 1996 ). Resistance to this new race of the golden nematode was found in a S. andigena and S. vernei population. The Ro2 resistant clones from this population are important parental materials for developing cultivars resistant to this new race of golden nematode. Long, russet-
skinned and red-skinned cultivars with resistance to this new race of the golden nematode are nonexistent. The location of the resistance gene for race Ro1 has been mapped (Pineda et al., 1993). Resistance to Ro2 appears to be controlled by a single gene (Chacon et al., 1999). Location of the gene(s) controlling resistance to Ro2 is being pursued at Cornell. Germplasm resistant to both the golden and white potato cyst nematodes and adapted to the North American climate has recently been released by the Cornell program (Brodie et al., 2000).

Potato Viruses. Potato viruses, a particular problem for seed producers, are presently controlled by certification, inspection, and vector reduction. Host resistance that reduces severity is beneficial unless it masks foliar symptoms without preventing virus buildup in the plant tissue. Consequently, very susceptible selections may be discarded, but marginal improvement in resistance is seldom a breeding objective. The potential for severe phloem (net) necrosis damage in tubers, caused by potato leaf roll virus (PLRV), is a serious defect and most breeding lines in the East are eliminated if they express this defect. PVY is a genetically diverse virus that has increasingly become a severe problem in many seed production areas in North America. While PVY is harmful to potato productivity, presence of certain PVY strains (e.g. PVYN and PVYNTN) in potato tissue can lead to virus spread to related crops which are highly sensitive to these viral strains. This has resulted in strict regulatory controls against these virus strains. Genes controlling resistance to potato virus X (Ritter et al., 1991), PVY Brigneti et al., 1997; Hamalain et al., 1997), and PLRV (Marczewski et al., 2001) have been mapped. Eva, a variety recently released by Cornell University, is resistant to both potato viruses X and Y.

Regional Evaluation and Modeling Efforts. Performance data obtained from collaborative trials in the NE-184 project have provided a rich and unique source of information for examining genotype x environment interactions of potato selections in the East. The project has developed two sets of "baseline" data: one consisting of five industry standards to be grown at all sites for each season; the other being "breeders choices" where each of the participating breeders indicates one to three selections that everyone should test at all sites for that year. This dataset provides the opportunity to compare performance of many new breeding selections in a short period of testing.

A problem associated with the data is that not all selections are evaluated in all trials. This represents the situation of "incomplete two-way tables" in statistical analysis (Ouyang et al., 1995, Patterson and Thompson, 1971). Recent developments in statistical methodology provide a number of new and efficient procedures to examine such data. The analytic results give much insight on the interplay between genotype and environments. A preliminary report on marketable yield of round, white-skinned potatoes indicates the usefulness of a linear regression method to evaluate the performance and adaptability of selections (Tai et al., 1993). Advanced statistical methods have been used on an annual basis to investigate the NE-184 trial data (Tai et al., unpublished). These methods are based on the multivariate statistical methodology and are capable of handling incomplete two-way tables. Analytic results using the statistical methods, Residual Maximum Likelihood (REML, Genstat, 1993; Horgan, 1992), Best linear unbiased predictor (BLUP) and AMMI (Additive Main Effects and Multiplicative Interaction effects, Zobel et al., 1988; Gauch, 1992) on the yield data for several years of data provided useful information on comparing the relative merits of breeding lines, test environments, and genotype x environment (GE) interactions. Investigation was also initiated on using cluster analysis to classify selections in terms of their response to the environments. A great deal of progress has been achieved on the statistical methods to study GE interactions of crop species over the past 10 years (Cornelius, 1993; Cornelius et al., 1993; Crosa, 1990; Crossa et al, 1995; Gauch and Zobel, 1997; Haynes et al., 1995 and 1997; Kang, 1990; Kang and Gauch, 1996; Tai, 1999; Tai and Coleman, 1999; Yan et al., 2000). The NE-184 project will continue to work with our rich dataset and new statistical tools to help describe performance of selections, understand GE interactions, and refine the evaluation and selection process.