Variability of Phytonutrient Content of Potato in Relation to Growing Location and Cooking Method

Potato has a defined complement of metabolites that contribute to the human diet. Among these are the carotenoids and anthocyanins. Carotenoids are found in all potatoes in the flesh. White-fleshed varieties have 50 to 100 μg per 100 g fresh weight (FW), while moderately yellow-fleshed varieties will generally possess from 100 to 350 μg per 100 g FW. The more intensely yellow-fleshed genotypes, which may look orange, at the higher extremes are at levels above 1,000 μg per 100 g FW. The highest level published is 2,600 μg per 100 g FW in diploid germplasm derived from South American Papa Amarilla cultivars. Potato generally has predominantly lutein, a xanthophyll which is also found in the human retina, and must be obtained in the diet. The genotypes with extremely high levels of total carotenoids have zeaxanthin, an isomer of lutein, which is also present in the human retina. Anthocyanins are present in red- or purple-skinned and fleshed varieties. Total anthocyanins range from 1.5 mg to 48 mg per 100 g FW in a solidly pigmented purple-skinned, purple-fleshed breeding line. The degree of pigmentation in the flesh appears to be under polygenic control. Anthocyanins are potent antioxidants and anti-inflammatory substances. The level of total anthocyanins is correlated with antioxidant level (r?=?0.94, P?<?0.001). Several methods of cooking interacted with genotypes in the antioxidant level remaining after cooking compared to raw potatoes. No method of cooking completely eliminated antioxidant activity, while boiling appeared to increase it compared to raw potato in the case of the most highly pigmented clone.     

Genotypic variation in the response of potatoes (Solanum tuberosum L.) to high ambient temperatures and water deficit

The response of potatoes to the major environmental stresses which prevail in a hot-dry climate, i.e., high temperature and water deficit, was studied. Nine potato cultivars and one unnamed clone of contrasting maturity classification were tested in the field under favorable climatological conditions in the spring and under high temperature conditions in the summer. In both seasons the plants were subjected to moderate and severe water deficits. In the spring, yield losses of 0 – 44% and 0 – 47% of fresh and dry weights, respectively, were obtained under moderate water stress, and losses of 16 – 55% and 2 – 52% of fresh and dry weights, respectively, under severe water stress. Under high ambient temperatures in the summer season and with adequate water supply, yield losses ranged from 0 – 96% compared with the spring crop yields, indicating the extreme susceptibility of some genotypes to heat stress. In all cultivars yield losses due to drought were much greater in the summer than in the spring. The early cultivars ‘Blanka’ and ‘Monalisa’ were less sensitive to changes in the environment, while the later maturing cultivars ‘Cara’ and ‘Desiree’ were very sensitive, being the highest yielding cultivars under the most favorable conditions. Early maturation was closely correlated with smaller yield losses in the summer, pointing to the possible involvement of an escape mechanism in the tolerance to heat stress. The differential response of the various genotypes to drought indicates the possible improvement of tolerance to drought in the potato. The possibility of improving adaptation to high temperatures is discussed.     

Characterization of forty-four potato varieties for resistance to common scab,black scurf and silver scurf

Common scab, black scurf and silver scurf belong to serious diseases of cultivated potato that especially impair tuber quality. Tuber infection in 44 potato (Solanum tuberosum ssp. tuberosum L.) varieties was evaluated using two measures – severity and incidence of infected tubers. Both measures were highly correlated. An important result derived from this study supports fungicide application against potato late blight secondarily acts on reducing tuber infection by all evaluated pathogens. Therefore, the conventional potato growing seems to be more effective compared to ecological growing. The pedigree analysis of 44 varieties indicated the presence of Solanum demissum genotypes in the variety genome may negatively affect variety response to Helminthosporium solani presence.     

Losses during Storage of Potato Varieties in Relation to Weather Conditions during the Vegetation Period and Temperatures during Long-Term Storage

Degradation of harvested tubers due to water loss, sprouting, and disease can cause severe economic difficulties in the cultivation of potatoes (Solanum tuberosum). This study evaluated the storage losses of new varieties of potato and determined the sprouting dates of potatoes stored at different temperatures. Additionally, this study evaluated the influence of weather conditions during the vegetative growth period on the date of sprouting in storage. After storage at three different temperatures (3, 5, and 8 °C), we estimated natural losses and losses caused by sprouting or the development of disease. The potato varieties stored at 3 °C, and 5 °C had similar weight losses (8.8% and 9.3%, respectively), but the potatoes stored at 8 °C had higher losses (10.8%). The average potato losses caused by disease ranged from 0.6% to 10%. The onset of sprouting of potatoes stored at 8 °C depended on the variety and began in the 20 day of December. Storage at 5 °C delayed sprouting by about 50 days compared with storage at 8 °C. Weather conditions (hot and rainy) during vegetative growth of the plants also influenced sprouting date, natural losses, and the amount of disease during storage. Our data showed a significant correlation between the hydrothermal coefficient during the vegetative period and the date of sprouting of potatoes during storage.     

Characterization of the Tolerance against Zebra Chip Disease in Tubers of Advanced Potato Lines from Mexico

Potato zebra chip disease (ZC), a threat to potato production in the USA, Mexico, New Zealand, and Central America, is associated with the bacterium “Candidatus Liberibacter solanacearum” (Cls) that is vectored by the potato psyllid (Bactericera cockerelli Sulc.). ZC control currently depends on insecticide applications, but sustainable control will require development of resistant and/or tolerant varieties. This study characterized four promising potato lines (246, 865, 510 and NAU) exposed to Cls-positive adult psyllids in choice and no-choice assays for ZC resistance. Psyllids preferred to settle on Atlantic over 246 and 865, and oviposit on Atlantic compared to 510. However, tolerance to ZC appeared more dependent on host responses to Cls infection. All four of these potato genotypes exhibited putative ZC tolerance in raw tubers compared to the susceptible commercial variety Atlantic. Expressed tolerance was associated with reduced concentrations of phenolic compounds in Cls-infected raw tubers with corresponding reductions in freshly-cut symptoms. However, these four genotypes exhibited ZC-linked discoloration of fried tuber slices, which was associated with increased sugar content that occurred following Cls-infection. As a result, these four ZC-tolerant experimental potato lines could be useful if the tubers produced are used for fresh, but not processing, markets.     

Screening for Chip-Processing Potato Line from Introgression of Wild Species’ Germplasms with Post-Harvest Storage and Chip Qualities

The processing of potatoes into chips is expanding in China. There is a need for new processing cultivars that are well-suited for the local ecological environment. Eleven potato varieties were bred from hybridization and backcrossing between the local cultivated potato varieties (Solanum tuberosum L.) and wild potato species. Lines from different wild species’ germplasms showed that the ability to accumulate reducing sugars was significantly different during low temperature storage (4 °C). A correlation analysis was conducted to determine the correlation coefficient among reducing sugars, acid invertase, free amino acids, chip colors and the content of acrylamide after storage at room and low temperatures. The lines 0706-116, 0737-6 and 0726-205 had low levels of reducing sugars, acrylamide content and acceptable chip colors for potato chip processing. The results indicated that the transfer of wild species’ processing traits into local cultivars by hybridization and continuous backcrossing is an effective potato breeding method and that the wild germplasm resources S. phureja and S. chacoense are suitable for improving the processing traits of local varieties.     

马铃薯资源抗旱性鉴定和筛选

干旱是马铃薯生产的重要限制因子之一.本研究利用42个马铃薯材料(品种),采用正常浇水和干旱胁迫两种理,对供试材料进行了抗旱能力评价.结果表明:虎头和高原7号等四倍体品种以及CE 66和HS 66等二倍体材料抗旱能力较强,其中高原7号和虎头等品种在干旱胁迫下表现出了较高产量,适宜应用于抗旱育种.干旱胁迫下,植株株高普遍降...     

Screening of Iranian Potato Germplasm for Resistance to the Potato Tuberworm Phthorimaea operculella (Lepidoptera: Gelechiidae)

The potato tuberworm, Phthorimaea operculella (Zeller), is an important insect pest of potato, Solanum tuberosum L., both in storage and in the field. In this research, tubers of eight commercial potato cultivars and four Iranian selections with equal weight and dormancy were exposed to 10 pairs of adult P. operculella in a climate chamber set at 25?±?1 °C, 65?±?5 % RH and total darkness. In a free-choice situation, oviposition was lower on 397082–2, Khavaran and Morene compared to the other germplasm that were exposed to adults of P. operculella. Number of mines per tuber, length of mines per tuber, time of development of larvae, number of pre-pupae produced per tuber, weight of pre-pupae and number of eggs developed in ovaries per female were counted and/or measured on each commercial cultivar and selection. There were fewer and shorter mines on tubers of 397082–2, Khavaran and Morene compared to the other potato germplasm. The number of pre-pupae produced per tuber and the weight of pre-pupae were lower when P. operculella was reared on tubers of 397082–2, Khavaran and Morene. Also the development, survival and fecundity were lower when P. operculella was reared on those same germplasm. Flesh firmness was negatively correlated with larval survival (r ²?=?0.87); in addition, the percentage of starch and macronutrient composition was low on these three germplasm. Thus, tuber flesh firmness of these germplasm could delay larval penetration and lower establishment 397082–2, Khavaran and Morene showed promising traits that can be integral component of potato breeding for resistance to P. operculella and pest management programs.     

Relationship Between Tuber Storage Proteins and Tuber Powdery Scab Resistance in Potato

The potato genotypes (Solanum tuberosum L.) with russet tuber skin are generally resistant to powdery scab (Spongospora subterranea f.sp. subterranea or Sss). Lipoxygenase (LOX; EC 1.13.11.12) and patatin are two key storage proteins that are known to offer resistance to several diseases and insects. The objective of this study was to find out the relationship of these proteins in stored tubers with potato tuber powdery scab resistance, especially in russet skinned potatoes. An evaluation of potato germplasm with different tuber characteristics in a greenhouse environment over several years (2006–’11) suggests that russet skinned tuber genotypes (Mesa Russet, Centennial Russet and Russet Nugget) with negligible tuber disease severity index (DSI) and 100 % marketability were resistant to powdery scab. Higher physiological levels of LOX protein (on a dry weight basis) were negatively correlated with tuber DSI and positively correlated with tuber russet skin. Tuber total protein and patatin-lipase levels did not have a significant relationship with tuber powdery scab resistance. The proposed role of LOX protein in suberin- and/or non-suberin-mediated mechanisms of powdery scab resistance in russet skinned tubers are discussed here. The physiological levels of LOX protein can be considered as a useful marker for powdery scab resistance in potato breeding programs.     

Antioxidant Protection Mechanisms Reveal Significant Response in Drought-Induced Oxidative Stress in Some Traditional Rice of Assam,India

Drought tolerance levels and antioxidant protection mechanisms were evaluated for 21 traditional rice varieties of Assam, India, along with Sahbhagi Dhan (drought tolerant) and IR64 (drought sensitive) as controls. Drought was imposed in hydroponic culture with polyethylene glycol 6000 (PEG6000) that was initially standardized with different concentrations. All the rice varieties showed apparent decreases in growth characteristics under drought stress (initially at 15% for 7 d followed by 20% PEG6000 for 7 d in Yoshida medium). On the basis of standard evaluation score (SES), eight rice varieties showed high drought tolerance which were carried forward for further biochemical analyses. Based on different morpho- physiological parameters, SN03 (Bora), SN04 (Prosad Bhog), SN05 (Kola Joha), SN06 (Helash Bora), SN08 (Salihoi Bao), SN12 (Kola Amona), SN20 (Ronga Bora) and SN21 (Sok-Bonglong) were identified as promising drought tolerant varieties. The non-enzymatic antioxidants activities viz., glutathione, ascorbate and enzymatic antioxidant activities such as superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), glutathione reductase (GR) in shoots and roots of all the selected varieties revealed significant level of protection mechanisms as compared with controls. Enhancement in activities of the overall antioxidant enzymes including SOD, GPX, CAT, GR and APX under drought stress reflects their role in the adaptation process under water stress.     

Yield Response of Potato (<Emphasis Type="Italic">Solanum tuberosum L</Emphasis>.) Genotypes to Late Blight Caused by <Emphasis Type="Italic">Phytophthora infestans</Emphasis> in Uganda

Potato (Solanum tuberosum L.) is a major food and cash crop, mainly grown by small-scale farmers in the highland regions of Uganda. Potato late blight is one of the major diseases limiting production with potential yield losses over 70%, making host resistance a strong element in integrated disease management. This study was carried out to screen and select high yielding potato genotypes with resistance to late blight in Uganda. Forty-eight genotypes, including advanced clones from the population B3C2 of the International Potato Centre, commercial and farmers’ varieties, were evaluated under two environments for two seasons. Trials were laid out in an 8?×?6 alpha lattice design with three replications. Genotypes showed significant differences in yield and resistance to blight. A higher disease severity was observed in Karengyere (56%). The average RAUDPC (= 100 max) across locations indicated that genotypes 395,077.12 and 392,657.8, with disease severity of 12% and 14%, respectively, were the most resistant. Genotypes Victoria (53%) and NKRN59.124 (48%) were the most susceptible. Mean tuber yield under late blight infection was19.8 t ha^?1. The best yielding genotype across sites was 395,112.32 (35.6 t ha^?1) while 394,905.8 (10.3 t ha^?1), yielded the lowest. The mean marketable tuber weight was 8.9 kg with genotypes 395,112.32 and 395,109.34 having the highest marketable weight of 16.5 kg and 15.6 kg respectively. Correlations between yield and yield related parameters were positive (p ≤?0.001), while those between RAUDPC were negative. The following genotypes, 395,112.32, 391,919.3, 393,220.54. 393,077.54, 396,038.107. 392,657.8, Kinigi, 395,014.17, NKRN59.58, NKRK19.17 and 395,011.2, were identified as promising parents for a late blight resistance breeding program. These exhibited high to medium resistance to late blight disease and high yields.     

Measurement of cellular membrane thermostability to evaluate foliage heat tolerance of potato

Summary Cellular membrane thermostability of leaf tissue, measured by both leaching and direct conductivity, was used as an index for evaluating potato (Solanum tuberosum L.) leaf tolerance to high temperature. Experiments with eight genotypes showed that maximum differences between cultivars in response to temperature occurred at 52.5°C. The wide variability among the genotypes suggested that this index could be used to screen potato foliage for tolerance to heat. The results agreed well with visual scoring after exposing potted plants to 52.5°C. CPRI Publication No 854.     

Rooting Characteristics of <Emphasis Type="Italic">Solanum chacoense</Emphasis> and <Emphasis Type="Italic">Solanum tuberosum in Vitro</Emphasis>

The precise level of environmental control in vitro may aid in identifying genetically superior plant germplasm for rooting characteristics (RC) linked to increased foraging for plant nitrogen (N). The objectives of this research were to determine the phenotypic variation in root morphological responses of 49 Solanum chacoense (chc), 30 Solanum tuberosum Group Phureja – Solanum tuberosum Group Stenotomum (phu-stn), and three Solanum tuberosum (tbr) genotypes to 1.0 and 0.5 N rate in vitro for 28 d, and identify genotypes with superior RC. The 0.5 N significantly increased density of root length, surface area, and tips. All RC were significantly greater in chc than in either phu-stn or tbr. Based upon clustering on root length, surface area, and volume, the cluster with the greatest rooting values consisted of eight chc genotypes that may be utilized to initiate a breeding program to improve RC in potato.     

Salt tolerance variability amongst Argentine Andean potatoes (Solanum tuberosum L. subsp.andigena)

Summary Salt tolerance in Andean potatoes can be a source for this trait in cultivated potatoes or be exploited to expand potato cultivation to more marginal areas. The purpose of this study was to determine salt tolerance in twelve Argentine Andean potato varieties through the response of nodal segments cultured in vitro and to evaluate whether changes in Na⁺, K⁺ or proline accumulation associate with salt tolerance. Genotypes Bianca, Airampia, Sisa Sani and Cuarentilla were the most tolerant. The most susceptible varieties were Balcacha, Runa Rosada, Collareja, Overa, Bianca Redonda and Papa Baya, while Cuarentona and Colorado Ml comprised an intermediate group. These results indicate that variability for salt tolerance exists in this germplasm, and highlights its potential use in breeding programmes. No association was found between the salt tolerance rating and changes in K⁺, Na⁺ and proline accumulation in a salt gradient, thus precluding the use of these parameters as predictors for salt tolerance of these species in in vitro studies.     

Co-current introgression of economically important traits in a potato-breeding program

Wild potato species contain many traits of economic importance. Late blight (LB) resistance and cold chipping are traits desired in potato cultivars. These traits could be co-currently introgressed if they occurred together in wild potato species. Our research objectives were (1) to determine if variation for cold chipping exists between potato species, accessions within species, and plants within accessions all having foliar LB resistance, and (2) to identify wild potato genotypes combining LB resistance and cold chipping. Materials include 665 genotypes from 43 LB-resistant accessions of 12 potato species having Endosperm Balance Numbers (EBN) of 1, 2, and 4, and 59 LB-resistant genotypes retained from these accessions for breeding. Potato chips were made from greenhouse-grown tubers following storage at 4 C for 6 months. Chip color was scored 1–10, ≤ 4 is acceptable by industry standards. Most of the variation for chip color was due to differences between species. Species ranged in the percentage of acceptably chipping genotypes (0% – 67%) with nine of 12 species having cold-chipping genotypes. Appreciable variation was present within accessions as well. The best chipping accessions wereS. verrucosum plant introduction (PI) 161173 – 4.33 / 0.67 (mean / proportion acceptable genotypes),S. stoloniferum PI 250510 -4.36 / 0.64,S. pinnatisectum PI 347766 -4.65 / 0.35 and 275233 -4.73 / 0.44, andS. megistacrolobum PI 195210 -5.14 / 0.29. Eleven 1EBN genotypes fromS. pinnatisectum andS. trifidum and five 2EBN genotypes fromS. verrucosum, S. fendleri,S. stoloniferum, andS. microdontum were identified that combined LB resistance and cold chipping. Co-current introgression would require fewer breeding cycles than other breeding methods to identify hybrid genotypes possessing both traits.     

Behavioral responses of adult potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae), to potato germplasm and transmission of Candidatus Liberibacter psyllaurous

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a major pest of potatoes that can cause yield loss by direct feeding on crop plants and by transmitting a bacterial pathogen, Candidatus Liberibacter psyllaurous (a.k.a. Candidatus Liberibacter solanacearum) associated with zebra chip disease of the crop. In recent years, there have been no studies regarding resistance of potato to the potato psyllid or the bacterial pathogen that the psyllid transmits. Thus, the objectives of this study were to determine the effects of potato germplasm on adult potato psyllid behavior and transmission of Ca. L. psyllaurous. A total of twenty-two potato (Solanum tuberosum L.) breeding clones and varieties were examined. Plant genotype significantly affected the occurrence and duration of psyllid probing, the duration of psyllid cleaning, resting and the amount of time psyllids spent off the potato leaflet as well as transmission of Ca. L. psyllaurous. For the potato genotypes in which there were significant decreases in transmission compared to controls, there was often an unclear relationship between the occurrences and duration of behaviors and subsequent bacterial transmission. We discuss the implications of our results for an integrated pest management program for the potato psyllid and Ca. L. psyllaurous control on potatoes.     

Evaluation of physiological traits as indirect selection criteria for drought tolerance in sugar beet

Drought is the most important limitation to sugar beet (Beta vulgaris L.) production in the UK and other areas dependent on usually insufficient summer rainfall. As increased irrigation is not a viable answer to the problem, an economically and environmentally desirable solution is new varieties with decreased sensitivity to water deficits. However, there is little genotypic information on drought tolerance in sugar beet, and breeders are not equipped to make these selections. The objectives of this study were to assess the degree of genotypic diversity for drought-related morpho-physiological traits and to measure the strength of association between these traits and indicators of crop performance. 46 sugar beet genotypes with diverse genetic backgrounds were tested in three field experiments from 1999 to 2001. Drought was imposed by covering plots with large polythene tunnels, allowing the crop to grow solely on stored soil moisture. Agronomic characters and drought tolerance indices are described in a companion paper [Ober et al., Assessing the genetic resources to improve drought tolerance in sugar beet. Agronomic traits of diverse genotypes under droughted and irrigated conditions. Field Crops Res., in press]. In this report, we show that there were significant genotypic differences for stomatal conductance, succulence index, specific leaf weight, and osmotic adjustment, but not for photosynthetic rate, relative water content or total water use. Patterns of water use within the soil profile differed between genotypes; some extracted more water from deep soil layers. The maintenance of green foliage cover during drought was positively correlated with drought tolerance index, which was negatively correlated with succulence index and scores for wilting and leaf senescence. Droughted sugar yield was positively correlated with soil water extraction and negatively correlated with relative leaf expansion rate measured in late summer. Under irrigated conditions, there was high positive correlation between transpiration rate and sugar yield. Genotype × trait biplots showed superior genotypes with relatively greater expression of combinations of favourable traits. The results suggest that succulence index and wilting score could be used to cull inferior plants in early stages of breeding programs, and green foliage cover and patterns of water use could help identify superior genotypes in elite germplasm. These data should enable tools to be developed for indirect selection of genotypes suited to drought-prone environments.     

水分胁迫下甘薯的生理变化与抗旱性的关系

用不同浓度的ＰＥＧ对甘薯进行了根际水分胁迫处理,研究叶片相对含水量（ＲＷＣ）,丙二醛（ＭＤＡ）含量,超氧物歧化酶（ＳＯＤ）活性及游离脯氨酸（Ｐｒｏ）含量的变化与品种抗旱性的关系。结果表明,在一定范围内,随着水分胁迫的加剧,甘薯叶片ＲＷＣ逐渐降低,ＭＤＡ含量ＳＯＤ活性及Ｐｒｏ含量逐渐升高。水分胁迫下生理指标的变化与品种抗旱性间有较好的一致关系。