Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “programmed genetic variation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed2005

Selection theory for marker-assisted backcrossing.

Marker-assisted backcrossing is routinely applied in breeding programs for gene introgression. While selection theory is the most important tool for the design of breeding programs for improvement of quantitative characters, no general selection theory is available for marker-assisted backcrossing. In this treatise, we develop a theory for marker-assisted selection for the proportion of the genome originating from the recurrent parent in a backcross program, carried out after preselection for the target gene(s). Our objectives were to (i) predict response to selection and (ii) give criteria for selecting the most promising backcross individuals for further backcrossing or selfing. Prediction of response to selection is based on the marker linkage map and the marker genotype of the parent(s) of the backcross population. In comparison to standard normal distribution selection theory, the main advantage of our approach is that it considers the reduction of the variance in the donor genome proportion due to selection. The developed selection criteria take into account the marker genotype of the candidates and consider whether these will be used for selfing or backcrossing. Prediction of response to selection is illustrated for model genomes of maize and sugar beet. Selection of promising individuals is illustrated with experimental data from sugar beet. The presented approach can assist geneticists and breeders in the efficient design of gene introgression programs.

Alleles↗
PubMed1990

Perturbation of the ubiquitin system causes leaf curling, vascular tissue alterations and necrotic lesions in a higher plant.

A ubiquitin variant with Lys48 changed to Arg acts in vitro as an inhibitor of ubiquitin dependent protein degradation. To assess the role of this proteolytic pathway in the life cycle of plants, we expressed the ubiquitin variant in Nicotiana tabacum. Expression of variant mono- or polyubiquitin leads to marked abnormalities in vascular tissue. In addition, overexpression of variant polyubiquitin induces discrete lesions on leaves. This indicates that perturbations of the ubiquitin system can induce a programmed necrotic response in plants.

Arginine↗
PubMed2006

Odds ratio based multifactor-dimensionality reduction method for detecting gene-gene interactions.

MOTIVATION: The identification and characterization of genes that increase the susceptibility to common complex multifactorial diseases is a challenging task in genetic association studies. The multifactor dimensionality reduction (MDR) method has been proposed and implemented by Ritchie et al. (2001) to identify the combinations of multilocus genotypes and discrete environmental factors that are associated with a particular disease. However, the original MDR method classifies the combination of multilocus genotypes into high-risk and low-risk groups in an ad hoc manner based on a simple comparison of the ratios of the number of cases and controls. Hence, the MDR approach is prone to false positive and negative errors when the ratio of the number of cases and controls in a combination of genotypes is similar to that in the entire data, or when both the number of cases and controls is small. Hence, we propose the odds ratio based multifactor dimensionality reduction (OR MDR) method that uses the odds ratio as a new quantitative measure of disease risk. RESULTS: While the original MDR method provides a simple binary measure of risk, the OR MDR method provides not only the odds ratio as a quantitative measure of risk but also the ordering of the multilocus combinations from the highest risk to lowest risk groups. Furthermore, the OR MDR method provides a confidence interval for the odds ratio for each multilocus combination, which is extremely informative in judging its importance as a risk factor. The proposed OR MDR method is illustrated using the dataset obtained from the CDC Chronic Fatigue Syndrome Research Group. AVAILABILITY: The program written in R is available.

Fatigue Syndrome, Chronic↗
PubMed2004

Molecular distinction between populations of Gonatocerus morrilli, egg parasitoids of the glassy-winged sharpshooter from Texas and California: do cryptic species exist?

Two molecular methods were utilized to distinguish geographic populations of Gonatocerus morrilli (Howard) from Texas and California and to test the possibility that this species could exist as a species-complex. Inter-Simple Sequence Repeat-Polymerase Chain Reactions (ISSR-PCR) were performed with a 5'-anchored ISSR primer. Twenty-five markers were generated with four populations (40 individuals) of G. morrilli. Twenty-three were polymorphic and the percentage of polymorphic loci was 92%. Most markers could be considered diagnostic since there was no band sharing between the Texas and California populations. Such differences typically are not found unless the populations are reproductively isolated. Exact tests for population differentiation indicated significant differences in marker frequencies among the populations. Comparison of other genetic differentiation estimates, which evaluate the degree of genetic subdivision, demonstrated excellent agreement between GST and theta values, 0.92 and 0.94, respectively, indicating that about 92 to 94% of the variance was distributed among populations. The average genetic divergence (D), as measured by genetic distance, was extremely high (Nei = 0.82 and Reynolds = 2.79). A dendrogram based on Nei's genetic distance separated the Texas and California populations into two clusters, respectively. Amplification of the Internal Transcribed Spacer-1 (ITS-1) region showed no size differences, whereas the ITS-2 DNA fragment varied in size between the two geographic populations. The ITS-2 fragment sizes were about 865 and 1099 base pairs for the California and Texas populations, respectively. The present study using the two molecular methods provides novel data critical to the glassy-winged sharpshooter/Pierce's disease biological control program in California.

Animals↗
PubMed2005

Molecular heterogeneity of beta-thalassemia in the United Arab Emirates.

The beta-thalassemia alleles in 313 national patients of the United Arab Emirates (UAE) have been characterized using PCR-based DNA-diagnostic techniques including DNA sequencing. A total of 212 patients had homozygous beta-thalassemia and the remaining 101 were compound heterozygotes. More than half of the patients were homozygous for the IVS-I-5 (G-->C) mutation followed by the sickle cell gene. The latter accounted for 25% of the chromosomes. In terms of frequency, five beta-thalassemia mutations; IVS-I-5 (G-->C), betaS, -25 bp del, Cd 8/9 (+G) and IVS-II-1 (G-->A) accounted for 83% of the alleles. In addition, 427 expatriate patients were studied: 256 with homozygous beta-thalassemia and 171 were compound heterozygotes. In both the UAE nationals and expatriates, the beta-thalassemia mutations and their frequency followed a similar trend. Our results indicate that the frequency of beta-globin gene defects including beta-thalassemia, sickle cell gene (betaS) and abnormal hemoglobins is significantly increased and poses a major public health problem in the UAE. The number of homozygous patients strongly suggests a high degree of consanguinity among the UAE nationals. With 50 different beta-thalassemia alleles, UAE is arguably the most heterogeneous population in the world. The diversity of these mutations reflects the historical admixture of genes and their migration from different areas in the region. Our data strongly suggest the need for a comprehensive thalassemia control program and provides a basis for population screening, genetic counseling and prenatal diagnosis.

DNA Mutational Analysis↗
PubMed2004

The use of molecular typing to evaluate the dissemination of antimicrobial resistance among Gram-negative rods in Brazilian hospitals.

Antimicrobial resistance has increased rapidly in Brazil and worldwide during the past few years, giving rise to a growing necessity for antimicrobial resistance surveillance programs. These programs have been instituted in order to monitor bacterial resistance in various regions, and to guide empirical antimicrobial therapy. We evaluated the use of molecular typing in multicenter surveillance programs. We also studied the dissemination modes of selected resistance profiles. Antimicrobial susceptibility to various antimicrobial agents was evaluated by the reference broth microdilution method. Bacterial isolates with selected susceptibility patterns were characterized by pulsed field-gel electrophoresis (PFGE). A total of 119 Gram-negative bacteria were molecularly typed, including 22 imipenem-resistant Pseudomonas aeruginosa, 26 ESBL-producing Escherichia coli, 27 cefoxitin-resistant-ESBL-producing Klebsiella pneumoniae, 33 Enterobacter spp., 8 Citrobacter spp., and 3 S. marcescens isolates resistant to ceftazidime. The isolates were from clinically apparent bacteremia of patients hospitalized in medical centers located in 13 cities of 11 Brazilian states. Our molecular typing results revealed a great genetic diversity among isolates of the same species. However, some major PFGE patterns were found in more than one isolate. All repeated PFGE patterns were detected in only 2 isolates, which were isolated within the same institutions or in different medical centers. We conclude that the ability to characterize organisms phenotypically and genotypically is a powerful epidemiologic tool and it provides unique information that is very important for multicenter surveillance programs.

Anti-Bacterial Agents↗
PubMed1987

Cytoplasmic genetic effects on preweaning growth and milk yield in Hereford cattle.

Performance records on Hereford cattle raised in two herds were used to evaluate cytoplasmic genetic effects on preweaning growth and milk production. Animals were traced through maternal lineage to foundation females to form cytoplasmic lines. Growth records were available on 1,189 calves at Raleigh and 1,599 at Plymouth representing 27 and 15 cytoplasmic lines, respectively. Milk records were available on 418 cows at Raleigh and 522 cows at Plymouth, representing 20 and 13 cytoplasmic lines. After adjustment for sire, cytoplasmic effects were significant for birth weight (BWT), average daily gain (ADG) and 205-d weight (WT205) in both herds. Cytoplasm accounted for 2, 5 and 5% of the variance for BWT, ADG and WT205 at Raleigh; and 1, 2 and 2% of the variance at Plymouth. After addition of maternal grandsire to the model, cytoplasm was still significant; however, variances were reduced at Plymouth. Cytoplasmic effects for milk yield were important at Raleigh (P less than .01) but marginal at Plymouth (P = .10). Variance components for cytoplasm accounted for 4 and 1% of the variance for milk yield at Raleigh and Plymouth, respectively. Ranges for least-squares constants for cytoplasmic lines corresponded to one of two standard deviations. Correlations among least-squares constants for ADG, WT205 and milk yield were high, suggesting that cytoplasmic effects were mediated through milk production. More research is needed to confirm these results before cytoplasmic inheritance is considered in breeding programs for beef cattle.

Animals↗
PubMed1991

The diversity of connexin genes encoding gap junctional proteins.

The multigene family of connexins is larger than previously anticipated. Ten different connexin homologous sequences have been characterized in the mouse genome, five of which are probably the mouse analogues of the known rat connexins26, -31, -32, -43, and -46. Since the additional 5 sequences have been isolated as cDNAs or hybridize specifically to distinct mRNA species, they most likely represent functional connexin genes. Since seven of the genomic connexin sequences have been shown to contain no intron in the coding sequence, this may apply to all mammalian connexin genes. Some of the structural features based on amino acid sequences deduced from cDNA or genomic sequences and the RNA expression pattern of the new connexins are compared with previously described connexins. The structural diversity of the connexin genes suggests that they fulfill different functions coordinated with, and perhaps required for, different programs of cellular differentiation.

Amino Acid Sequence↗
PubMed2001

Phylogenetic relationships among Portuguese rye based on isozyme, RAPD and ISSR markers.

The phylogenetic relationships of 10 rye landraces and cultivars from the north of Portugal and from Brazil were analysed using 20 isozyme loci, and a total of 511 PCR markers (342 ISSRs and 169 RAPDs). The isozymes were analysed in at least 100 plants of each population/cultivar and, therefore, we have data about intra and inter population/cultivar genetic variability. However, the analyses with ISSRs and RAPDs were obtained using a mix of 25 plants of each population. Therefore, each population/cultivar was reduced to one tube and we have no data about intra genetic variability. As expected in a cross pollinated crop we found genetic diversity and a larger variation within than among the populations using isozymes. Somewhat unexpectedly, however, we found that the breeding cultivars have the same level of heterozygosity as the landraces. The phylogenetic relationships obtained using isozymes among the landraces, synthetic cultivar and the cultivars from breeding programs do not reflect their origin. Moreover, the cultivar from Brazil is not separated from the remaining populations/cultivars studied. However, the data observed using RAPDs and ISSRs are in agreement with their known origin. The populations maintained by the farmers in the north of Portugal are grouped in a cluster in the phenogram and the C902591 (from Brazil), the Alvão (synthetic variety) and Larouco (a hybrid between Montalegre and Brazil) are in a different cluster. The ISSRs and RAPDs provide a rapid method for the production of polymorphic markers, which appear to correspond to known pedigree information.

Alleles↗
PubMed1994

A simple method for censored age-of-onset data subject to recall bias: mothers' reports of age of puberty in male twins.

Genetic analysis of variation in age of onset of development milestones or psychopathological behaviors has been little researched, owing largely to the computational difficulty of dealing with "censored" observations. Censored observations arise when the only information on individuals is that they have reached a particular age but without onset having occurred. This paper shows how models can be simply fitted to such data using programs that can perform genetic analysis of categorical data by maximum likelihood. The method is illustrated using the program Mx with data on maternal report of the onset of puberty in twin sons from the Virginia Twin Study of Adolescent Behavioral Development. Frequently, data on age of onset is collected by retrospective recall. This can pose a variety of measurement problems. Suggestions are made for models that account for some of these problems or are robust to their presence. Substantial evidence for "telescoping" of onset dates is found for the puberty data. If left unaccounted for, these effects can artifactually inflate estimates of common environment effects.

Adolescent↗
PubMed2003

[Plasma amino acids profile of healthy pregnant adolescents in Maracaibo, Venezuela].

One hundred female adolescents (13-18 y) were clinical and anthropometrically studied to select only those with adequate nutrition. Most adolescents belonged to IV socio-economic stratum families (worker class). Height, weight, age, body mass index and medial arm circumference were used as anthropometric parameters. After screening, only 41 non pregnant girls (control) and 42 pregnant girls with adequate nutrition were selected to analyze plasma amino acids. Fasting peripheral venous blood was drawn, and plasma amino acids were analyzed by HPLC. Amino acid concentrations were expressed as umol/L +/- SE. SAS/STAT program was used for statistical analysis. Amino acid values of control adolescent group were found in ranges reported by other investigators, with slight variations, mostly in diminution, presumably due to nutritional, metabolic or genetic conditions of people living in tropical regions. In pregnant healthy adolescents, distributed according to gestational age: < 32 weeks (n = 30) and > 32 weeks (n = 12), a diminution of total molar plasma amino acids was found, by comparing with control values. Ten amino acids (Pro, Gly, Gln, Arg, Ser, Orn, Tau, Leu, Thr and Val) appeared significantively diminished throughout gestation, being Gly. Gln and Arg most affected since earlier weeks. During the 2nd period. Thr and Val increased their grade of affectation; whereas some amino acids values (Orn, Pro and Tau) tended to recuperate. Several of affected amino acids are gluconegoenic, thus, they could be utilized to supply the energy required by the pregnant adolescent against her double stress: the fetus development and her own development. The plasma amino acid values reported in both, healthy non pregnant and pregnant adolescents, could be taken as regional referential profile of plasma amino acids in this poblational group for further research on adolescent and fetal--maternal malnutrition.

Adolescent↗
PubMed1989

[Role of the code redundancy in determining cotranslational protein folding].

It has been demonstrated earlier in our laboratory that rare codon clusters can determine the boundaries of the polypeptide chain fragments of the same secondary structure type during the co-translational protein folding. According to this data, co-translational protein folding can occur under condition of a correlation between the frequency of codon choice in mRNAs and the relative abundance of their isoaccepting tRNAs. The alterations in the spectrum and concentrations of the isoaccepting tRNAs in different cells were demonstrated by many authors. The existence of a mechanism of the coordinate regulation of the levels (activities) of the isoaccepting tRNAs, corresponding aminoacyl-tRNA synthetases and mRNAs predominantly translated at a given moment of time can be suggested. Such a mechanism can ensure the needed accuracy of the protein folding process. Analysis of gene sequences of various pro- and eukaryotic organisms carried out in the present work revealed that the codon usage frequency spectra of simultaneously synthesized proteins are similar. The relative appearance of the most rare and frequent codons in investigated gene sequences displays a high degree of conservatism. It has also been found that structural-homologous proteins from different organisms (cytochromes c, myoglobins) have very similar codon frequency distribution profiles. This property retains despite the significant variations in the codon usage spectra in the investigated gene sequences. The data obtained indicate that the codon distribution in mRNAs whose diversity is mainly conditioned by the genetic code redundance is a program that determines translational rates of different mRNA parts thus controlling the spatial folding of the synthesized peptide chain.

Animals↗
PubMed2005

Molecular evolution of the sheep prion protein gene.

Transmissible spongiform encephalopathies (TSEs) are infectious, fatal neurodegenerative diseases characterized by aggregates of modified forms of the prion protein (PrP) in the central nervous system. Well known examples include variant Creutzfeldt-Jakob Disease (vCJD) in humans, BSE in cattle, chronic wasting disease in deer and scrapie in sheep and goats. In humans, sheep and deer, disease susceptibility is determined by host genotype at the prion protein gene (PRNP). Here I examine the molecular evolution of PRNP in ruminants and show that variation in sheep appears to have been maintained by balancing selection, a profoundly different process from that seen in other ruminants. Scrapie eradication programs such as those recently implemented in the UK, USA and elsewhere are based on the assumption that PRNP is under positive selection in response to scrapie. If, as these data suggest, that assumption is wrong, eradication programs will disrupt this balancing selection, and may have a negative impact on the fitness or scrapie resistance of national flocks.

Animals↗
PubMed2004

Genetic diversity of peanut (Arachis hypogaea L.) and its wild relatives based on the analysis of hypervariable regions of the genome.

BACKGROUND: The genus Arachis is native to a region that includes Central Brazil and neighboring countries. Little is known about the genetic variability of the Brazilian cultivated peanut (Arachis hypogaea, genome AABB) germplasm collection at the DNA level. The understanding of the genetic diversity of cultivated and wild species of peanut (Arachis spp.) is essential to develop strategies of collection, conservation and use of the germplasm in variety development. The identity of the ancestor progenitor species of cultivated peanut has also been of great interest. Several species have been suggested as putative AA and BB genome donors to allotetraploid A. hypogaea. Microsatellite or SSR (Simple Sequence Repeat) markers are co-dominant, multiallelic, and highly polymorphic genetic markers, appropriate for genetic diversity studies. Microsatellite markers may also, to some extent, support phylogenetic inferences. Here we report the use of a set of microsatellite markers, including newly developed ones, for phylogenetic inferences and the analysis of genetic variation of accessions of A. hypogea and its wild relatives. RESULTS: A total of 67 new microsatellite markers (mainly TTG motif) were developed for Arachis. Only three of these markers, however, were polymorphic in cultivated peanut. These three new markers plus five other markers characterized previously were evaluated for number of alleles per locus and gene diversity using 60 accessions of A. hypogaea. Genetic relationships among these 60 accessions and a sample of 36 wild accessions representative of section Arachis were estimated using allelic variation observed in a selected set of 12 SSR markers. Results showed that the Brazilian peanut germplasm collection has considerable levels of genetic diversity detected by SSR markers. Similarity groups for A. hypogaea accessions were established, which is a useful criteria for selecting parental plants for crop improvement. Microsatellite marker transferability was up to 76% for species of the section Arachis, but only 45% for species from the other eight Arachis sections tested. A new marker (Ah-041) presented a 100% transferability and could be used to classify the peanut accessions in AA and non-AA genome carriers. CONCLUSION: The level of polymorphism observed among accessions of A. hypogaea analyzed with newly developed microsatellite markers was low, corroborating the accumulated data which show that cultivated peanut presents a relatively reduced variation at the DNA level. A selected panel of SSR markers allowed the classification of A. hypogaea accessions into two major groups. The identification of similarity groups will be useful for the selection of parental plants to be used in breeding programs. Marker transferability is relatively high between accessions of section Arachis. The possibility of using microsatellite markers developed for one species in genetic evaluation of other species greatly reduces the cost of the analysis, since the development of microsatellite markers is still expensive and time consuming. The SSR markers developed in this study could be very useful for genetic analysis of wild species of Arachis, including comparative genome mapping, population genetic structure and phylogenetic inferences among species.

Alleles↗
PubMed2003

Molecular diversity and multilocus organization of the parental lines used in the International Rice Molecular Breeding Program.

One hundred and ninety three parental lines obtained from 26 countries for an international rice molecular breeding program were evaluated using 101 well-distributed simple sequence repeat (SSR) markers. An overall genetic diversity of 0.68 and an average of 6.3 alleles per locus were revealed, indicating a high level of genetic variation in these lines. Cluster analysis of the 193 accessions showed three major groups and nine subgroups. Group I corresponded to the classical indica subspecies, whereas groups II and III belong to the japonica subspecies. Indica and japonica differentiation accounted for only 6.5% of the total variation in the entire sample and 93.5% was due to within-subspecies diversity. Differentiation among eco-geographic regions accounted for 24% of the diversity within the subspecies. Larger amounts of the eco-geographical differentiation were resolved within japonica than within indica. The largest indica-japonica differentiation based on the single locus level was detected by markers on chromosomes 9 and 12, while the smallest differentiation was detected by markers on chromosomes 4 and 8. Furthermore, genetic differences at the single-locus and two-locus levels, as well as components due to allelic and gametic differentiation, were revealed between indica and japonica and among the main geographic regions. The multilocus analysis in genetic diversity showed a higher proportion of variation caused by predominant non-random associations of different loci within and among the classified subspecies and geographic subdivisions. The results suggest that selection for eco-geographical adaptation on multilocus associations was largely responsible for the maintenance of the extensive variation in the primary gene pool of rice.

Alleles↗
PubMed2005

BioAfrica's HIV-1 proteomics resource: combining protein data with bioinformatics tools.

Most Internet online resources for investigating HIV biology contain either bioinformatics tools, protein information or sequence data. The objective of this study was to develop a comprehensive online proteomics resource that integrates bioinformatics with the latest information on HIV-1 protein structure, gene expression, post-transcriptional/post-translational modification, functional activity, and protein-macromolecule interactions. The BioAfrica HIV-1 Proteomics Resource http://bioafrica.mrc.ac.za/proteomics/index.html is a website that contains detailed information about the HIV-1 proteome and protease cleavage sites, as well as data-mining tools that can be used to manipulate and query protein sequence data, a BLAST tool for initiating structural analyses of HIV-1 proteins, and a proteomics tools directory. The Proteome section contains extensive data on each of 19 HIV-1 proteins, including their functional properties, a sample analysis of HIV-1HXB2, structural models and links to other online resources. The HIV-1 Protease Cleavage Sites section provides information on the position, subtype variation and genetic evolution of Gag, Gag-Pol and Nef cleavage sites. The HIV-1 Protein Data-mining Tool includes a set of 27 group M (subtypes A through K) reference sequences that can be used to assess the influence of genetic variation on immunological and functional domains of the protein. The BLAST Structure Tool identifies proteins with similar, experimentally determined topologies, and the Tools Directory provides a categorized list of websites and relevant software programs. This combined database and software repository is designed to facilitate the capture, retrieval and analysis of HIV-1 protein data, and to convert it into clinically useful information relating to the pathogenesis, transmission and therapeutic response of different HIV-1 variants. The HIV-1 Proteomics Resource is readily accessible through the BioAfrica website at: http://bioafrica.mrc.ac.za/proteomics/index.html.

Africa↗
PubMed2003

Molecular characterization of Buffalograss germplasm using sequence-related amplified polymorphism markers.

Buffalograss [ Buchloe dactyloides (Nutt.) Englem] germplasm has a broad resource of genetic diversity that can be used for turfgrass, forage and conservation. Buffalograss is the only native grass that is presently used as a turfgrass in the Great Plains region of North America. Its low growth habit, drought tolerance and reduced requirement for fertilizer and pesticides contribute to interest in its use. The objectives of this study were to use sequence-related amplified polymorphism (SRAP) markers in the evaluation of genetic diversity and phenetic relationships in a diverse collection of 53 buffalograss germplasms, and to identify buffalograss ploidy levels using flow cytometry. Based on their DNA contents, buffalograss genotypes were grouped into four sets, corresponding to their ploidy levels. Thirty-four SRAP primer combinations were used. This is the first report of the detection of differentiating diploid, tetraploid, pentaploid and hexaploid buffalograss genotypes, representing diverse locations of origin, using SRAP markers. Cluster analysis by the unweighted pair-group method with arithmetic averages based on genetic similarity matrices indicated that there were eight clusters. The coefficients of genetic distance among the genotypes ranged from 0.33 up to 0.99 and averaged D=0.66. The genetic diversity estimate, He, averaged 0.35. These results demonstrated that genotypes with potential traits for turfgrass improvement could readily be distinguished, based on SRAP. The use of PCR-based technologies such as SRAP is an effective tool for estimating genetic diversity, identifying unique genotypes as new sources of alleles for enhancing turf characteristics, and for analyzing the evolutionary and historical development of cultivars at the genomic level in a buffalograss breeding program.

DNA, Plant↗
PubMed2004

High level of genetic diversity among spelt germplasm revealed by microsatellite markers.

The genetic diversity of spelt (Triticum aestivum (L.) Thell. subsp. spelta (L.) Thell.) cultivated presently is very narrow. Although the germplasm collections of spelt are extensive, the related genetic knowledge is often lacking and makes their use for genetic improvement difficult. The genetic diversity and structure of the spelt gene pool held in gene banks was determined using 19 simple sequence repeat (SSR) markers applied to 170 spelt accessions collected from 27 countries and 4 continents. The genetic distances (1 - proportion of shared alleles) were calculated and an unweighted pair-group method with arithmetic averaging (UPGMA)-based dendrogram was generated. The genetic diversity was high: 259 alleles were found and the mean interaccession genetic distance was 0.782 +/- 0.141. The dendrogram demonstrated the much higher genetic diversity of spelt held in germplasm collections than in the currently used genotypes. Accessions with the same geographical origin often tended to cluster together. Those from the Middle East were isolated first. All but one of the Spanish accessions were found in a unique subcluster. Most accessions from eastern Europe clustered together, while those from northwestern Europe were divided into two subclusters. The accessions from Africa and North America were not separated from the European ones. This analysis demonstrates the extent of genetic diversity of spelts held in germplasm collections and should help to widen the genetic basis of cultivated spelt in future breeding programs.

Alleles↗