Processing characteristics of Solanum tuberosum—S. stoloniferum hybrids

Two hybrids having high total solids were compared with established commercial varieties for processing into french fries, potato chips, and potato flakes. Russet Burbank was used as a control for potato flakes and french fries, and Kennebec for potato chips. The hybrids were processed initially at harvest and at two intervals after harvest. The solids in the hybrids varied from 23.0% to 26.9% and the products generally had a better color and yielded more product per pound of raw material than the controls. The hybrids had a high level of xanthophyl, stable in the french fries and potato chips but unstable in the potato flakes. Antioxidants retarded the loss of the yellow color in the flakes. Oil absorption was found to be inversely related to solids in the potato chips and french fries. By means of sensory evaluation, the hybrids were generally considered different from the controls with respect to color, flavor, and texture but no preferences were obtained. Potatoes with high solids result in more finished product per pound of raw material.     

Goldrush: A new high quality russet-skinned potato cultivar

On March 1, 1992, the North Dakota Agricultural Experiment Station announced the release of a new russet potato cultivar named Goldrush. Goldrush is an oblong, smooth, russet-skinned potato cultivar that has very white flesh, good culinary quality, resistance to hollow heart and is adapted for both the fresh and processing market.     

Extreme resistance to infection by potato virus Y and potato virus X in an advanced hybridSolanum phureja — S. Stenotomum diploid potato population

Samples of 4285 individuals from a hybridSolanum phureja Juz. et Buk. —S. stenotomum Juz. (Phu-Stn) and 105 individuals ofSolanum phureja (Phu) diploid potato populations were twice inoculated with potato virus Y strain “o” (PVY°) using the air brush technique. After discarding seedlings with PVY visual symptoms both in the greenhouse and in the field, 1508 seedlings were judged to be resistant to PVY° (35.2%). Only 5.7% of the Phu seedlings were PVY° resistant compared to 35.2% of the Phu-Stn seedlings. At harvest, a mild selection pressure for yield and tuber appearance was applied and 602 Phu-Stn clones were chosen for further evaluation. Selected clones were re-evaluated for PVY° resistance in the greenhouse. Clones were mechanically inoculated twice with PVY°. Clones susceptible to PVY° were determined by visual observations, ELISA (Enzyme-linked immunosorbent assay) tests, grafting of tobacco PVY° infected shoots on potato clones, and infectivity tests usingNicotiana tabacum as a PVY° plant indicator. In the process, 224 clones were found to be extreme resistant to infection by PVY°, with an overall frequency for PVY° extreme resistance of 5.2%. In another experiment, the first year Phu-Stn PVY° resistant clones (554 clones) were mechanically inoculated twice with “common” strain of potato virus X (PVX). Similarly, we discarded clones susceptible to PVX by combining visual evaluation and ELISA with PVX re-inoculation of negative clones and an infectivity test, usingGomphrena globosa as a PVX plant indicator. After this process, seven extreme resistant and eight resistant clones to infection by PVX were found; the overall frequency of PVX extreme resistance was 1.3%. Five clones were extreme resistant to both PVY° and PVX.     

Potato germplasm with combined resistance to leafroll virus and viruses X and Y

Potato germplasm with high levels of combined resistance to potato viruses X, Y, and leafroll was identified and used to produce improved parental clones with similarly high levels of resistance. Resistance was determined from the amount of tuber infection following inoculation of plants in the field. Parental germplasm with the best multiple resistance came from two backgrounds, eitherSolanum tuberosum group Andigena derived from the Cornell University neo-tuberosum program, or from complex hybrids ofS. tuberosum and wild solanums that were produced by the Max Planck Institute and the Polish Institute for Potato Research. Two Aberdeen, ID selections, A85519-6 and A85530-10, with gp. Andigena ancestry, have had no tuber-borne infection of PVX, PVY, or PLRV during four years of intensive field testing. We have not been successful in combining virus S resistance with resistance to the other viruses.     

Inheritance of potato chip color at the 24-chromosome level

Potato chip color is an important trait in determining quality and acceptability of cultivars for processing. Therefore, the genetics of potato chip color is important in varietal breeding. The use of 2xS. tuberosum Group Tuberosum haploid × 2x wild species hybrids provides disomic inheritance for genetic analysis of chip color. Two hundred forty haploid-species hybrids representing crosses between 15 haploids and 10 species were evaluated for potato chip color after 21 days reconditioning (18 to 20C) following 6 months at 4C. Phenotypic variation for chip color was found among the haploid-species hybrids. Crosses between good, medium, and poor performing clones were made in all combinations and 136 families were obtained. Progeny were evaluated for reversion resistance (chipping direct from 10C storage) and reconditioning (chipping from 4C after tuber warming) chip color. Variation for chip color was found among the progeny for each trait. Significant correlations between reversion resistance and reconditioning were found. Yet, the use of at least two chip tests (one for reversion resistance and one for reconditioning) is more informative than the use of one test and subsequent predictions made, regarding the other trait. A three locus hypothesis for both reversion resistance and reconditioning is proposed for the inheritance of each trait. One dominant allele at each of the three loci is necessary for good chipping. One or two loci may be common to both characteristics. Good chipping 2x hybrids that produce 2n pollen can be used to transfer this trait to the 4x level through use of 4x × 2x crosses.     

Relationships between fry color and sugar concentration in stored Russet Burbank and Shepody potatoes

Relationships between french fry color and sugar composition of Russet Burbank and Shepody potatoes harvested at various chemical maturities (i.e., sucrose concentrations) and exposed to various temperature regimes during 8 to 9 months storage were examined. Combined data from 3 years of study showed fry color to be more closely associated with glucose during 8 C storage for Russet Burbank (r²=0.65) and Shepody (r²=0.62) than with fructose, total reducing sugars, sucrose, or total sugars. Glucose > 1.6 mg g^?1 in Russet Burbank and > 1.2 mg g^?1 in Shepody resulted in fries which were too dark to be eligible for maximum bonus paid by processors for good color. Russet Burbank harvested with sucrose > 3.1 mg g^?1 and Shepody harvested with sucrose > 1.6 mg g^?1 and preconditioned for 14 d at 15 C before storage at 8 C accumulated enough glucose in storage to result in fries which were darker than was acceptable for maximum bonus payment. Preconditioning at 15 C for 70 d was necessary to prevent Russet Burbank with sucrose of 3.9 mg g^?1 at harvest from accumulating unacceptably high glucose during storage. Glucose determined with enzymatic test strips was in close agreement with that by HPLC for both cultivars. The test strips could be used to estimate fry color of Russet Burbank.     

Genetic relationships of Japanese potato cultivars assessed by RAPD analysis

Seventy-three breeding lines and cultivars, which included all Japanese cultivars, were assessed by random amplified polymorphic DNA (RAPD) analysis. Thirty-one of 40 decamer primers revealed 84 scorable RAPDs. Using these RAPDs, 67 of 73 cultivars were distinguished from each other. One of the cultivars released as a protoclonal variant was able to distinguish from the parent by increasing the number of primers surveyed. Based on the number of different RAPDs between each pair of accessions, cluster analysis was performed to exploit genetic diversity in Japanese cultivars. Closely related cultivars deduced from their pedigrees were clustered closely, indicating that similarities based on the presence vs. absence of RAPDs were reflections of genetic similarities. Old Japanese cultivars, as suggested by their similarity of chloroplast DNA toS. tuberosum ssp.andigena, were indeed clustered with ssp.andigena accessions, supporting these were relic cultivars of early European potatoes. The present study suggests that Japanese potatoes are an interesting mass of genetic diversity including North American, European, and Andean germplasms and relic potatoes.     

Use of seedling tubers from TPS in southern Italy

The TPS seedling tuber technique can be successfully adopted in developing as well as in developed countries as a standard agronomic system for potato production. Experimental work has been started in order to select the best parental lines and to evaluate the appropriate breeding schemes for the use of this technique in southern Italy. During 1989 48 true potato seed (TPS) families with different genetic backgrounds were tested for seedling tuber production and they produced a good yield. The seedling tuber families were tested for tuber production during 1990 by subdividing them in two size classes: 25mm-35mm and 35mm-45mm. The highest yield was attained by 4X x 2X families and the analysis of variance indicated significant differences with regard to tuber size and TPS families for both total and marketable tuber yield. This technique has significant potential for providing tubers for both the fall and winter crop in Italy.     

Diploid potato germplasm derived from wild and land race genetic resources

Diploid cultivated species, haploids derived from tetraploid cultivars, and their wildSolanum relatives were used to generate various diploid potato genetic stocks. These stocks have significant value in potato breeding because: 1) genetic diversity in the potato population can be kept variable with the diploid germplasm which confers genetic variation from wild and cultivated species; 2) crossability of this diploid germplasm is facilitated by the function of 2n gametes; and 3) high levels of pest resistances originating from the process of introgression of the wild and cultivated genetic resources can be used to improve the tetraploid cultivated potato genepool.     

Verticillium wilt resistant germplasm: Release of Russet clone B0169-56

Potato breeding selection B0169-56 is being released by the United States Department of Agriculture, Agricultural Research Service as germplasm that is highly resistant toVerticillium albo-atrum Reinke & Berthier andV. dahliae Kleb. In five years of field testing in the Verticillium wilt plot in Presque Isle, Maine, the level of resistance as measured by symptom severity is equal to that of Russette. In 1993, in plots inoculated with both species ofVerticillium, there was a 15,27 and 62% yield reduction for B0169-56, Russette, and Superior, respectively. After four years of evaluation in yield and processing trials in Presque Isle, Maine, B0169-56 has yielded and fried as well as Russet Burbank. Tubers are russet-skinned, oblong to long and cylindrical. Tubers of B0169-56 size early, a necessary quality for an eastern russet. It is both female and male fertile. This selection is currently undergoing further evaluation at multiple state locations for possible commercialization. Seed is available from the USDA/ARS, Beltsville, Maryland.     

Use of the virus strain group concept to characterize the resistance to PVX and PVYo in the potato cv Allegany

Resistance to the potato viruses X (PVX), Y (PVY) and A (PVA) was examined in the potato cv Allegany released by Cornell University in 1990. Standard potato cultivars from North America and Europe were included for characterization of the resistance response. Allegany was extremely resistant to a strain group 3 isolate of PVX and reacted with hypersensitivity to an ordinary strain isolate of PVY (PVY^o). However, Allegany was susceptible to an isolate of PVY causing necrosis in tobacco (PVY^N), and to an isolate of PVA. No symptoms appeared following infection with PVY^N and PVA. Identification of existing virus strain groups in a geographic area is an important aspect of predicting cultivar response to inoculation in the field.     

Comparison of some diagnostic assays for bacterial ring rot of potato: A case study

The results of testing 48 stems and tuber samples, representing 15 seed lots from several different growers, for the presence of the causal organism of bacterial ring rot,Clavibacter michiganensis subsp.sepedonicus with the gram stain, latex agglutination (LAT), enzyme-linked immunosorbent assay (ELISA), and a DNA hybridization assay (DHA) were compared. The frequency with which positive tests were obtained varied significantly among assays and was associated with symptom expression in samples. Detection was highest with the serological assays and lowest for DHA. Use of the gram stain, in conjunction with either LAT, ELISA, or DHA reduced the number of positive diagnoses, but increased the agreement between results for different assay combinations. Based on a comparison of results for both individual samples and seed lots, the performance of LAT and ELISA for diagnostic purposes were equivalent. DHA was found to be less useful due to limitations in test sensitivity forC. m. sepedonicus, but it does give unequivocal diagnoses of samples where bacterial populations are sufficient to allow detection.     

RBM134: A mutant of Russet Burbank susceptible to blackspot bruise

A radiation induced mutant of Russet Burbank was recovered that is more susceptible to blackspot bruise than the original cultivar. The mutant was evaluated and characterized for several agronomic and biochemical traits. Compared to Russet Burbank the mutant had slightly lower tuber yield, smaller average tuber weight, a higher number of tubers per plant, higher percent tuber dry matter, similar total tuber dry matter yield, lower tuber protein and higher free tyrosine content. Vine growth and appearance was indistinguishable from Russet Burbank. This mutant should provide an excellent tool for better understanding the tuber characteristics contributing to blackspot bruising in potatoes.     

Consecutive elisa screening with monoclonal antibodies to detect potato virus YN

In a 1992 survey of potato fields in Canada for the tobacco veinal necrosis strain of potato virus Y (PVY^N), initial enzyme-linked immunosorbent assay (ELISA) screening with one monoclonal antibody (MAb 295.5) followed by a second ELISA screening with a panel of several MAbs (4E7, Bioreba, 1F5 and 295.5) was assessed as a means of rapidly identifying positive samples prior to confirmation by bioassay. MAbs 4E7 and Bioreba were used in double antibody sandwich (DAS) ELISA, while MAbs 1F5 and 295.5 were used in triple antibody sandwich (TAS) ELISA. In the second ELISA, MAbs 4E7, 1F5 and Bioreba all enhanced test specificity relative to the retest with MAb 295.5. All the MAbs were found to react, to some degree, with isolates of the common strain of PVY (PVY^O), but MAb 4E7 was the most specific widi no cross-reaction being observed at, or above, the signal to noise (S:N) threshold of 4:1. However, this MAb was also the least sensitive. At the S:N threshold of 4:1, its sensitivity was 68%, compared to a sensitivity of close to 100% for the other MAbs     

Lemhi Russet: A new high yielding potato variety with wide adaptation,attractive tubers,and high internal quality

Lemhi Russet, a new oblong, russet-skinned potato variety, was released by the U.S. Department of Agriculture and the Agricultural Experiment Stations of Idaho, Oregon, California, Washington, and North Dakota on September 23, 1980. The tubers of Lemhi Russet have been blockier, larger, 6% higher in solids, 50% lower in reducing sugars, and 25% higher in vitamin C than those of Russet Burbank. Lemhi Russet has averaged 34% more U.S. No. 1 tubers than Russet Burbank in 6 years of trials in five states. It was superior to Norgold Russet in yield and specific gravity in early harvest trials. In pilot plant and laboratory trials, Lemhi Russet made excellent french fries, baked well with a mealy texture, but sloughed when boiled. Lemhi Russet has a high degree of resistance to scab and net necrosis, but is susceptible to potato viruses S, X, Y, and to the leafroll virus. It is also susceptible to bruising and blackspot.     

An approach to field screening potato genotypes for potato leaf roll virus resistance

Eight potato cultivars and two advanced breeder selections were assessed for field resistance to the potato leaf roll virus (PLRV) following field exposures in which PLRV-infected Russet Burbank plants were used as inoculum sources within treatments. This screening protocol provided consistent PLRV resistance ratings despite year-to-year variation in PLRV pressure. Secondary disease incidence based on enzyme-linked immunosorbent assay (ELISA) of foliage from tuber progeny ranged from 0–87% in 1990 and 0–67% in 1991, and was consistent with reported PLRV resistance ratings for eight of ten genotypes. Agreement between visual assessment and ELISA on plants from harvested tubers was 94% in 1990 and 83% in 1991, for all genotypes. However, agreement data were inconsistent from year-to-year, with the exception of three genotypes. In both years, current season infection, based on ELISA of foliage, was detected in less than two percent of the plants and, was inadequate as a measure of secondary PLRV incidence. Green peach aphid (GPA) populations did not differ among genotypes at sampling times during the season, but the PLRV concentration in GPA colonizing Russet Burbank plots was significantly higher than in GPA colonizing any other genotype.     

Identification of parents suitable for molecular mapping of immunity and resistance genes in solanum species

A survey of DNA polymorphisms and bacterial ring rot reactions inSolanum species was conducted to identify parents that when crossed would produce an F₁ mapping population useful for identifying DNA markers tightly linked to genes for immunity or resistance to bacterial ring rot.Solanum tuberosum, S. acaule, diploidSolanum species, doubled monoploid lines ofS. phureja, and somatic fusion hybrids betweenS. tuberosum andS. brevidens were established in tissue culture from single true potato seeds or tubers and evaluated for bacterial ring rot reactions in greenhouse studies with root-inoculated tissue cultured plantlets. Establishment of tissue culture stocks insured the availability of homogeneous genetic material for use in bacterial ring rot assays and genetic analyses. Presence ofClavibacter michiganense subsp.sepedonicum was assessed in stems by an immunofluorescence antibody assay (IFAS). Two accessions were found to be immune to bacterial ring rot. DNA polymorphisms were detected within and among 24 accessions evaluated with 24 RFLP markers and 10 arbitrary oligonucleotide primers (RAPDs). These results identify parents suitable for future mapping of gene (s) for immunity or resistance to bacterial ring rot.     

Nutrient concentration relationships between the fourth petiole and upper-stem of potato plants

Successfully evaluating the nutritional status of a crop during growth and development is dependent upon sampling an identifiable plant part. Consistently sampling a petiole of the same maturity in potatoes (Solanum tuberosum L.) is difficult. We evaluated the nutrient relationships between the upper-stem and the fourth petiole from Russet Burbank plants in field studies having N, P, K, Zn or Mn variables. The upper-stem was obtained by excising the stem below the sixth leaf and removing all leaves and the terminal meristem. Petole NO₃-N, P, K, Zn and Mn concentrations were from deficient to sufficient. The NO₃-N, P and K concentrations were similar in the fourth petiole and upper-stem, while the Zn concentration was 40% higher in the upper-stem. Calcium, Mg and Mn concentrations were lower in the upper-stem than in the fourth petiole. Copper and S relationships were not adequately defined. The fourth petiole’s NO₃-N, P and K diagnostic concentrations now used to monitor plant nutrient status can also be used for upper-stem samples. Zinc diagnostic concentrations should be increased, while Ca, Mg and Mn concentrations should be adjusted downward in the upper-tem. Additional data are needed to refine the Ca and Mg relationships, and to establish relationships for Cu, S and other essential nutrients. A significant advantage of using the upper-stem is the elimination of the petiole selection problem when sampling.     

Nitrogen and potassium fertilization of potatoes: Sugars and starch

Considerable evidence exists that both N and K influence potato (Solanum tuberosum L.) yields and quality. The impact of nutrients on tuber quality parameters under field conditions should be identified so optimum management practices can be utilized. We evaluated the N and K fertilization by K-sources effects on concentrations of nutrients, reducing sugars, sucrose and starch in the stem and apical tuber ends from two irrigated field experiments with the Russet Burbank cultivar. Nitrogen rates of 0,112, 224 or 336 kg ha^?1 were combined with selected K rates of 0, 112, 224 or 448 kg ha^?1 as either KCl or K₂SO₄ arranged as an incomplete factorial. A multiple linear regression model was fit to the data and used to predict the response surface for a complete factorial for each K-source. Nitrogen applications increased or decreased reducing sugars in the apical and stem ends, respectively. Potassium decreased reducing sugars in both tuber ends. Sucrose was higher in the apical end than in the stem end but was not appreciably affected by fertilizer treatment. Nitrogen and potassium applications reduced dry matter and starch concentrations in both tuber ends. Potassium had a smaller effect on the apical end when starch was expressed on a dry weight basis, indicating that increased water content was a factor in the K effect. Both N and K concentrations in the tuber ends were negatively related to starch concentrations, but the relationship was different for the apical and stem ends. Tuber Cl concentration indirectly affected starch concentrations in the stem end when KCL was applied. The K fertilization effect on specific gravity depended upon the K concentration in the harvested tuber and was independent of K fertilizer source. These data illustrate the effects of preplant N and K fertilization rates on final tuber quality parameters. Additional studies are needed to further define the effects of nutrient concentrations at different plant growth stages.     

Identification of genetic factors influencing chip color in diploid potato (Solanum spp.)

A genetic map was constructed with a combination of isozymes, restriction fragment length polymorphisms (RFLPs) and randomly amplified polymorphic DNA (RAPDs) to apply quantitative trait loci (QTL) analysis to identify genetic factors that contribute to chip color in potato. The diploid population used was a cross between aSolanum tuberosum haploid andS. chacoense hybrid used as female parent and aS. phureja clone used as male. Chip color was determined visually on samples fried from tubers stored at 10C. On a scale of 1 (light color) to 10 (dark color), the population ranged from 2 to 8 while the parents average chip color was 3.5. Based upon one-way ANOVAs (P < 0.05), 13 genetic markers showed significant associations which represent a total of six QTLs. A multiple locus model based upon the markers that have the largest effect per QTL explained 43.5% of the phenotypic variation for chip color in the population and increased to 50.5% when one significant epistatic interaction was included in the model. All the significant marker associations were identifed in theS. tuberosum-S. chacoense hybrid. Through preliminary data, the results of this study suggest that additive effects contribute a significant portion of the genetic variation for chip color. The identification of these QTLs for chip color variation provides the means to apply marker-assisted selection to introgress these genes into the cultivated potato germplasm.