Diverse Potato Research Articles

Analysis of Genetical Diversity of Some of the Tetraploides Potato Cultivars Grown in Iran

The genetical diversity of potato, Solanum tuberosum was assessed using morphological traits. To verify, how this diversity is distributed among the main potato varieties grown in Iran. A total of eleven potato varieties, Ramose, Sante, Shepody, Marfona, Maradona, Milova, Santana, Boren, Cosima, Granola and Agria, were evaluated under vivo and situ experimental conditions in Isfahan, conditions, Iran. Seven phenological, floral and morphological vegetative aerial descriptors, Growth Rate = CGR, Net Assimilation Rate = NAR, Leaf Area Duration = LAD, Leaf Area Ratio = LAR and specific Leaf Area = SLA were recorded. The descriptors were evaluated by SAS Software and their means comparison by DMRT test. Certain defined groups were observed, indicating that the diversity of the cultivars are structured with a considerable morphological variation in between the varieties with a very high significant growth indices.

HPLC profiling of phenolics in diverse potato genotypes

Potatoes from over fifty genotypes representing cultivars, breeding lines, primitive germplasm and wild species were analysed for phenolic content and hydrophilic antioxidant capacity. Genotypes with markedly higher amounts than the most commonly consumed potatoes were identified. Chlorogenic acid was the most abundant phenolic and ranged from 22 to 473mg/100gdryweight. Rutin and kaempferol-3-rutinose were the most abundant flavonols. Total phenolics ranged from 1.8 to 11mg/gDW and antioxidant capacity ranged from 27 to 219μmolTE/gDW. Total phenolics and antioxidants in these high-phytonutrient potatoes compared favourably to 15 other analysed vegetables. With the high per capita consumption of potatoes, widespread adoption of high-phytonutrient cultivars could significantly increase dietary intake of phytonutrients.

Underground assets: potato biodiversity to improve the livelihoods of the poor

Vulnerability and limited assets both constrain the options of poor people, especially smallholder farmers. But the poor often also possess a range of potentially valuable natural, physical, financial, human and social-capital assets. Development interventions requiring high levels of assets that poor people do not have are unlikely to reduce poverty, but those which build on what they do have can build assets and so improve their options. Producing and processing potatoes are important livelihood strategies for millions of the poor. A careful understanding of the context and strategies of the poor can help indicate how potatoes can also be used to reduce poverty. This paper employs the Sustainable Livelihoods Framework to examine these issues, using the Papa Andina case in the Andes as an example of new approaches to use potato diversity to improve livelihoods in a transforming development context. The Papa Andina regional initiative, together with its national partners, helps Andean farmers build new livelihood strategies using the genetic diversity of potatoes, local knowledge and social capital—assets that are often undervalued. But this does not occur in a vacuum; a range of policies and institutions are required, including, for example, collective action among farmers and interaction with outsiders such as market agents and agricultural service providers in order to foster market chain innovation and to access and build market opportunities. Accurate understanding of the changing context of producers, processors and consumers can help ensure that potatoes play a role in improving the welfare of the poor.

AFLP markers for the assessment of genetic diversity in european and North American potato varieties cultivated in Iran

Information about the genetic diversity of potato germplasm in Iran is important for variety identification and to enhance the classification of germplasm collections and exploit them in breeding programs and for the development and introduction of new varieties. AFLP fingerprinting was applied to a group of cultivated potato varieties to find if there is any geographical differentiation in potato diversity from Europe and North America. The high level of polymorphism within potato varieties and the high number of variety-specific bands suggest that AFLPs are powerful markers for diversity analysis in potato varieties. No region-specif ic AFLP markers were found (present in varieties from the same origin and absent in others). The UPGMA dendrogram revealed four distinct clusters corresponding almost to the geographical origin of the varieties. However, the bootstrap support for branches was rather weak. No clusters clearly distinguished varieties from Europe and North America. Varieties from the same geographical origins however tended to group together within each cluster. The mean similarity and the UPGMA dendrogram both suggest that North American varieties have nearly identical genetic diversity to European varieties. The results of AMOVA revealed large within-region variations which accounted for 94.5% of the total molecular variance. The between-region variation, although accounting for only 5.5% of the total variation, was statistically significant. AFLP technology was successfully used to evaluate diversity between different geographical groups of potatoes and is recommended for potato genetic studies.

Phytochemical Diversity in Tubers of Potato Cultivars and Landraces Using a GC-MS Metabolomics Approach

Phytochemical diversity with respect to a range of polar (including amino acids, organic acids, sugars, and sugar alcohols) and nonpolar (including fatty acids, alkanols, and sterols) metabolites was examined within tubers from a total of 29 genetically diverse potato cultivars and Chilean landraces using a metabolomics approach by gas chromatography-mass spectrometry. From principal component analysis of the polar and nonpolar metabolite data there was insufficient variation to differentiate the majority of cultivars and landraces. Analysis of all polar metabolite profiles revealed separation of two cultivars (Glenna and Morag) from the other cultivars and landraces and a separate cluster of one landrace line, largely due to higher levels of sugars. Pentland Javelin was distinct in containing high levels of many amino acids. The two Solanum tuberosum group phureja cultivars (Inca Sun and Mayan Gold) were not particularly similar and were not separated from the S. tuberosum group tuberosum cultivars. Analysis of the nonpolar metabolite data revealed partial separation of two landrace lines and, on the basis of some minor fatty acids, Mayan Gold was distinct. The differences in metabolite profiles are considered in terms of the taxonomy and breeding history of the cultivars and possible influences from other factors such as developmental stage of the tuber. With a view to exploring biosynthetic links between metabolites, a pairwise correlation analysis was performed on all metabolites. The significance of high correlations between many amino acids and between several nonpolar metabolites is discussed.

Methodologies and Traits for Evaluating the Salt Tolerance in Diploid Potato Clones

Efforts to incorporate the salt stress tolerance expressed by certain wild diploid potato species into improvement programs for cultivated tetraploid potatoes are hampered by a lack of quick, efficient and representative salt stress tolerance screening methods capable of evaluating diverse potato genotypes. This study developed screening methods and evaluated phenotypic and physiological responses as indicators of salt tolerance in diploid potato clones (Solanum tuberosum L. x wild relatives) utilizing a hydroponic sand-based system. When diploid clones known to vary in their salt tolerance were treated at tuber initiation with salinities ranging from 0 to 300 mM NaCl for 30 days, treatment with 100–150 mM NaCl allowed for rapid differentiation between salt tolerant and sensitive clones. Differences in relative salt tolerance were more clearly illustrated by changes in shoot growth and water content than by changes in shoot or root dry weights. Salt tolerances of 22 diploid potato clones were then evaluated by exposure to 100 to 150 mM NaCl stress for 28 days beginning at tuber initiation. Cluster analysis was used to segregate the clones into discrete groups based on the relative similarity of their responses to salt stress. Eight clones were subsequently selected to reflect a range in salinity tolerance and maturity. The eight clones were exposed to salinity stress for the reduced stress period of 7 days and then grown through to maturity. The 7 days stress period still allowed differentiation of tolerant versus sensitive clones. Growth index in both the 30 and 7 days salt stress trials was a good predictor of absolute tuber yield but not tuber yield tolerance to salt stress (tuber yield under stress / tuber yield under non-stress conditions). Tuber yield tolerance to salt stress was positively correlated with time to maturity. When the genotypes were ranked based on cluster analysis of a range of readily measured phenotypic and physiological responses to salt stress, the ranking was effective at predicting the relative impact of a salt stress event on tuber yield at maturity. While growth index may be a useful initial rapid selection tool, maturity and cluster analysis based on readily measured phenotypic characteristics were more effective in predicting relative yield tolerance to salt stress than individual phenotypic or physiological responses.

Hybridization between wild and cultivated potato species in the Peruvian Andes and biosafety implications for deployment of GM potatoes

The nature and extent of past and current hybridization between cultivated potato and wild relatives in nature is of interest to crop evolutionists, taxonomists, breeders and recently to molecular biologists because of the possibilities of inverse gene flow in the deployment of genetically-modified (GM) crops. This research proves that natural hybridization occurs in areas of potato diversity in the Andes, the possibilities for survival of these new hybrids, and shows a possible way forward in case of GM potatoes should prove advantageous in such areas.

Association mapping of quality traits in potato (Solanum tuberosum L.)

In this paper, we describe the assessment of linkage disequilibrium and its decay in a collection of potato cultivars. In addition, we report on a simple regression based association mapping approach and its results to quality traits in potato. We selected 221 tetraploid potato cultivars and progenitor lines, representing the global diversity in potato, with emphasis on genetic variation for agro-morphological and quality traits. Phenotypic data for these agro-morphological and quality traits were obtained from recent trials performed by five breeding companies. The collection was genotyped with 250 AFLP® markers from five primer combinations. The genetic position of a subset of the markers could be inferred from an ultra dense potato map. Decay of linkage disequilibrium was estimated by calculating the squared correlation between pairs of markers using marker band intensities. Marker-trait associations were investigated by fitting single marker regression models for phenotypic traits on marker band intensities with and without correction for population structure. The paper illustrates the potential of association mapping in tetraploid potato, because existing phenotypic data, a modest number of AFLP markers, and a relatively simple statistical analysis, allowed identifying interesting associations.

Determination of Folate Concentrations in Diverse Potato Germplasm Using a Trienzyme Extraction and a Microbiological Assay

Folate deficiency is a leading cause of birth defects and is implicated in several other diseases. We are interested in how much folate concentrations vary among potato germplasm. We determined total folate concentrations of potato tubers from 67 cultivars, advanced breeding lines, or wild species. Folates were extracted by a tri-enzyme treatment and analyzed by using a Lactobacillus rhamnosus microbiological assay. Folate concentrations varied from 521 +/- 96 to 1373 +/- 230 ng/g dry weight and were genotype and location dependent. The highest folate concentrations were mostly found in color-fleshed potatoes. Variations of folate concentrations within either color- or white-fleshed tubers were similar ( approximately 2-fold). Skin contained approximately 30% higher folate concentrations than flesh. Storage of tubers for 7 months generally led to an increase in folate contents. Semiquantitative RT-PCR analyses showed that higher folate contents were correlated with lower mRNA expression of some folate genes.

A Test of Taxonomic Predictivity: Resistance to White Mold in Wild Relatives of Cultivated Potato

A major justification for taxonomic research is its assumed ability to predict the presence of traits in a group for which the trait has been observed in a representative subset of the group. Taxonomy is regularly used by breeders interested in choosing potential sources of disease‐resistant germplasm for cultivar improvement. We designed this study as an empirical test of prediction by associating resistance to white mold [caused by the fungal pathogenSclerotinia sclerotiorum(Lib.) de Bary] to diverse potato (Solanumspp.) taxonomies and biogeography, using 144 accessions of 34 wild relatives of potato inSolanumsectionsPetotaandEtuberosumTremendous variation for resistance to white mold occurs both within and among species. No consistent association was observed between white mold resistance and taxonomic series (based on a phenetic concept), clades (based on a cladistic concept), ploidy, breeding system, geographic distance, or climate parameters. Species and individual accessions with high proportions of white‐mold‐resistant plants have been identified in this study, but both often exhibit extensive variation and designation of either as resistant or susceptible must take this variation into account. Therefore, taxonomic relationships and ecogeographic data cannot be reliably used to predict where additional sources of white mold resistance genes will be found.

MECHANIZATION OF POTATO GRADING ON SMALL-SCALE FARMS: A CASE STUDY FROM PERU

Potatoes are an important cash crop for small-scale producers worldwide. The move away from subsistence to commercialized farming, combined with the rapid growth in demand for processed agricultural products in developing countries, implies that small-scale farmers and researchers alike must begin to respond to these market changes and consider post-harvest treatment as a critical aspect of the potato farming system. This paper presents and assesses a low cost potato-grading machine that was designed explicitly to enable small-scale potato growers to sort tubers by size for supply to commercial processors. The results of ten experiments reveal that the machine achieves an accuracy of sort similar to commercially available graders. The machine, which uses parallel conical rollers, has the capacity to grade different tuber shapes and to adjust sorting classes, making it suitable for locations with high potato diversity. Its relatively low cost suggests that an improved and adapted version of this machine might enhance market integration of small-scale potato producers not only in Peru, but in other developing countries as well.

Physicochemical and kinetic properties of unique isozymes of UDP-Glc pyrophosphorylase that are associated with resistance to sweetening in cold-stored potato tubers

Isozymes of UGPase with unique catalytic properties were purified from the cold-induced-sweetening (CIS) resistant cultivar Snowden (Solanum tuberosum). Two distinct peaks of UGPase activity were obtained when protein extracts were subjected to anion-exchange chromatography on DEAE-Sephacel. Polypeptides in the first eluted fraction (A-I) were ionically similar to the UGPase isozyme UGP3 previously purified and characterized from the cold-sweetening sensitive cultivar Norchip (Sowokinos et al. 1993, Plant Physiol 101: 1073-1080). Seventy-two percent of the total endogenous UGPase activity in Snowden (cv.) tubers, however, was found in a more basic protein fraction (A-II) that is not found in the Norchip cultivar. This study reports on the physicochemical and kinetic properties of these new polypeptides that demonstrate UGPase activity. The reaction in the direction of UDP-Glc synthesis was specific for the substrates Glc-1-P and UTP and there was an absolute requirement for Mg2+ ions. The catalytic properties of UGP5 were markedly different from UGPase isozymes previously described in terms of (1) affinity for the substrate Glc-1-P, (2) pH optimum, (3) maximum reaction velocity and (4) sensitivity to product inhibition with UDP-Glc. Chi-square analysis of fifty-four genetically diverse potato lines revealed that resistance to CIS was highly correlated with the presence of the A-II isozymes of UGPase. The kinetic properties of these unique forms of UGPase may underlie, in part, a tuber's ability to resist sweetening in the cold.

Genetic Diversity in Diploid and Tetraploid Late Blight Resistant Potato Germplasm

An understanding of the genetic relationship within potato germplasm is important to establish a broad genetic base for breeding purposes. The objective of this study was to assess the genetic diversity of potato (Solanum tuberosum subsp. tuberosum Hawkes) germplasm that can be used in the development of cultivars with resistance to late blight caused by Phytophthora infestans (Mont.) de Bary. Thirty-three diploid and 27 tetraploid late blight resistant potato clones were evaluated for their genetic diversity based on 11 isozyme loci and nine microsatellites. A total of 35 allozymes and 42 polymorphic microsatellite fragments was scored for presence or absence. The germplasm was clustered based on the matrix of genetic similarities and the unweighted pair group means analysis of the isozyme and microsatellite data, which were used to construct a dendrogram using NTSYS-pc version 1.7. Twenty-three allozymes and DNA fragments were unique to the wild species. The diploid Solanum species S. berthaultii Hawkes and S. microdontum Bitter formed two distinct phenetic groups. Within S. microdontum, three subgroups were observed. The tetraploid germplasm formed another group, with S. sucrense Hawkes in one subgroup and the cultivated potato and Russian hybrids in another subgroup. Based upon the genetic diversity and the level of late blight resistance, S. microdontum and S. sucrense offer the best choice for strong late blight resistance from genetically diverse sources. This potato germplasm with reported late blight resistance should be introgressed into the potato gene pool to broaden the genetic base to achieve stronger and more durable resistance.

High-Resolution Metabolic Phenotyping of Genetically and Environmentally Diverse Potato Tuber Systems. Identification of Phenocopies

High-Resolution Metabolic Phenotyping of Genetically and Environmentally Diverse Potato Tuber Systems. Identification of Phenocopies

High-Resolution Metabolic Phenotyping of Genetically and Environmentally Diverse Potato Tuber Systems. Identification of Phenocopies

We conducted a comprehensive metabolic phenotyping of potato (Solanum tuberosum L. cv Desiree) tuber tissue that had been modified either by transgenesis or exposure to different environmental conditions using a recently developed gas chromatography-mass spectrometry profiling protocol. Applying this technique, we were able to identify and quantify the major constituent metabolites of the potato tuber within a single chromatographic run. The plant systems that we selected to profile were tuber discs incubated in varying concentrations of fructose, sucrose, and mannitol and transgenic plants impaired in their starch biosynthesis. The resultant profiles were then compared, first at the level of individual metabolites and then using the statistical tools hierarchical cluster analysis and principal component analysis. These tools allowed us to assign clusters to the individual plant systems and to determine relative distances between these clusters; furthermore, analyzing the loadings of these analyses enabled identification of the most important metabolites in the definition of these clusters. The metabolic profiles of the sugar-fed discs were dramatically different from the wild-type steady-state values. When these profiles were compared with one another and also with those we assessed in previous studies, however, we were able to evaluate potential phenocopies. These comparisons highlight the importance of such an approach in the functional and qualitative assessment of diverse systems to gain insights into important mediators of metabolism.

Assessing genetic diversity of sweet potato (Ipomoea batatas (L.) Lam.) cultivars from tropical America using AFLP

The sweet potato genebank at the International Potato Center (CIP) maintains 5,526 cultivated I. batatas accessions from 57 countries. Knowledge of the genetic structure in this collection is essential for rational germplasm conservation and utilization. Sixty-nine sweet potato cultivars from 4 geographical regions (including 13 countries) of Latin America were randomly sampled and fingerprinted using AFLP markers. A total of 210 polymorphic and clearly scorable fragments were generated. A geographic pattern of diversity distribution was revealed by mean similarity, multidimensional scaling (MDS), and analysis of molecular variance (AMOVA). The highest genetic diversity was found in Central America, whereas the lowest was in Peru-Ecuador. The within-region variation was the major source of molecular variance. The between-regions variation, although it only explains 10.0% of the total diversity, is statistically significant. Cultivars from Peru-Ecuador, with the lowest level of within region diversity, made the most significant contribution to the between region differentiation. These results support the hypothesis that Central America is the primary center of diversity and most likely the center of origin of sweet potato. Peru-Ecuador should be considered as a secondary center of sweet potato diversity.

The Ecogeography of Andean Potatoes

Adaptation to varied habitats confers ecological versatility and the capacity for coarse-grained distribution across heterogeneous habitats, whereas ecological specialization implies a restricted pattern. Ecogeography and adaptive traits help to determine whether farmers are able to adjust their diverse crops to socioeconomic and environmental changes (a process known as in situ conservation) or whether they are led to abandon them. Abandonment adds to the likelihood of local extinctions (genetic erosion). Versatility and specialization, and the corresponding ecogeography traits, thus require different strategies for the conservation of agricultural biodiversity, which is a primary goal of sustainable development. The diversity and farming of Andean potatoes offer a useful ex-

Genetic diversity of potato determined by random amplified polymorphic DNA analysis

The RAPD procedure was used to establish genetic diversity of 28 potato genotypes including siblings and genotypes with no immediate relationship. In addition amplified DNA from three parents and Solanum chacoense were compared with that from six progeny to determine the genetic relationships. Amplification of genomic DNA from the 28 genotypes using PCR and 12 decamer primers yielded 158 amplified DNA fragments, ranging in size from 490 to 3200 bp. A total of 128 unique RAPD fragments were observed among the 28 potato genotypes. Similarity measures and principal coordinate analysis generally reflected the expected trends in relationships of the full and half-sib potato genotypes. However there were important exceptions to this general trend and it appears that related varieties can be as genetically different as varieties with no immediate relationship. The data suggest that RAPD analysis used in conjunction with pedigree information can provide a superior measure of genetic divergence than analysis based solely on pedigree information.

Genetic diversity of potato determined by random amplified polymorphic DNA analysis

Genetic diversity of potato determined by random amplified polymorphic DNA analysis

Potato Diversity in the Andean Center of Crop Domestication.

The diversity and population structure of potato landraces (Solanum spp.) within their center of domestication was studied using isozyme surveys of four polymorphic loci. The objective in assessing the distribution of genetic diversity was to assist in planning conservation strategies of crop genetic resources that are threatened by genetic erosion. In situ conservation methods depend on this type of analysis. Research was conducted in the region of Cusco, Peru. Eight fields spread among two microregions were randomly sampled, and 610 tubers were studied from this sample. In addition, 503 tubers were collected from markets in seven different meso-regions (provinces) surrounding the regional center of Cusco. Thirty genotypes were identified in the field sample and 82 in the regional sample. The frequency and distribution of genotypes and alleles are described. A high degree of genotype endemism was found at both the field and regional levels. Genotypes were unevenly distributed, and most of the genotypic diversity was between rather than within populations. At the allele level, however, we found that a very high percentage of the diversity was within rather than between populations. The genotype is the key unit for maintaining the population of potato landraces. Our findings suggest that collections need to be both geographically extensive and intensive. Because farmers are able to maintain most alleles on relatively small portions of their land, in situ conservation is a viable strategy.