A-genome cotton as a source of genetic variability for Upland cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis>)

Since Upland cotton (Gossypium hirsutum) is known to have relatively low levels of genetic diversity, a better understanding of variation and relationships among possible sources of novel genes would be valuable. Therefore, analysis of genetic variation of the genus Gossypium, especially the diploids, which are the putative donors of the A and D genomes for the commercially important allotetraploid cottons (AADD), G. hirsutum and G. barbadense, could provide important information about the feasibility of using these genetic resources for cotton improvement. The primary objective of this study was to analyze the genetic diversity in A-genome diploid cotton species, G. herbaceum (A1) and G.␣arboreum (A2) by using microsatellite markers. Forty-one A-genome germplasm accessions were evaluated with 32 microsatellite loci. Genetic similarities between A1 and A2 ranged from 0.62 to 0.86 with a mean of 0.70. Within each A-genome species similarities ranged from 0.80 to 0.97 with a mean of 0.89 for A1 and from 0.82 to 0.98 with a mean of 0.89 for A2. A UPGMA tree and principal coordinate analysis based on genetic similarity matrices showed distinct clusters consistent with the genomic groups.     

Evaluation of Gossypium arboreum L. Germplasm for resistance to thrips

Summary As part of a project to assess the U.S. Asiatic Cotton Germplasm Collection as a source of genes for pest resistance, forty-three accessions of Gossypium arboreum L. were evaluated for resistance to thrips. Thrips, Thysanoptera spp., are a minor, but widespread pest on cotton, G. hirsutum L. and G. barbadense L. Accessions were planted in free-choice field tests in 1988, 1989, and 1990 at the Cotton Branch Experiment Station, Marianna, Arkansas. Damage ratings, based on a scale of 0 (no damage) to 7 (severe damage), were made approximately one month after planting. Relative score was computed by dividing the rating of each accession by the rating of the reference, G. hirsutum Stoneville 506. The relative score averaged over all G. arboreum accessions by year varied with the year, but was less than 100 (relative score for Stoneville 506) in each case. When data were combined for all three years, twenty-five accessions were significantly better than Stoneville 506. Introgression of the better accessions into G. hirsutum is now in progress.Abbreviations NPGS National Plant Germplasm System - STV 506 G. hirsutum Stoneville 506     

Identification of AFLP Markers that Discriminate Between Cultivated Cotton and the Hawaiian Island Endemic, <Emphasis Type="Italic">Gossypium tomentosum</Emphasis>Nuttall ex Seeman

Interspecific gene flow from crop species into wild relatives may compromise the genetic integrity of native species and in the case of transgenic crops lead to the escape of transgenes into natural populations. Approximately 72% of the upland cotton (Gossypium hirsutum L.) acreage grown in the United States in 2000 utilized transgenic cultivars. The closest relative of G. hirsutum is G. tomentosum Nuttall ex Seeman, endemic to the Hawaiian archipelago. Because these two species are fully interfertile, cultivation of transgenic G. hirsutum in the Hawaiian Islands is restricted. We investigated the possibility of identifying AFLP genetic markers that are diagnostic for each species and thus could be used in future studies to detect introgression between them. In addition, we were interested in comparing levels and geographic patterns of AFLP diversity in G. tomentosum to previous estimates using allozyme data. AFLP analysis led to the detection of 11 and 16 species-specific markers for G. tomentosum and G. hirsutum, respectively. These species-specific AFLP markers will be useful for detecting gene flow between G. hirsutum and G. tomentosum that has occurred in the past and thus might occur in the future if the restrictions on cultivation of transgenic G. hirsutum are relaxed in the Hawaiian Islands. Little genetic diversity and limited geographic patterning were discovered using AFLP markers, consistent with data from previous allozyme studies.     

Studying the extent of genetic diversity among Gossypium arboreum L. genotypes/cultivars using DNA fingerprinting

Genetic diversity is an area of concern for sustaining crop yield. Information on genetic relatedness/diversity among Gossypium arboreum L. cultivars/genotypes is scanty. We have used random amplified polymorphic DNA (RAPD) analysis to assess the genetic divergence/relationship among 30 genotypes/cultivars of G. arboreum. Of 45 primers surveyed, 63% were polymorphic. Out of the total number of loci amplified, 36% were polymorphic. The calculated genetic similarity between the cultivars/genotypes was in the range of 47.05–98.73%. Two genotypes, HK-244 and Entry-17, were the most distantly related. The average genetic relatedness among all the genotypes was 80.46%. However, most of the cultivated varieties showed a close genetic relationship, indicating a narrow genetic base in comparison to the non-cultivated germplasm. The calculated coefficients were used to construct a dendrogram using the unweighted pair group of arithmetic means (UPGMA) algorithm, which grouped the genotypes/cultivars into two major and three smaller clusters. The study is the first comprehensive analysis of the genetic diversity of G. arboreum germplasm and identifies cultivars that will be useful in extending the genetic diversity of cultivated varieties and future genome mapping projects.     

Response of A-genome cotton germplasm to the seedling disease pathogens,Rhizoctonia solani and Pythium ultimum

Summary Approximately two hundred A-genome cotton (Gossypium arboreum L. and G. herbaceum L.) accessions were evaluated for resistance to the seedling disease pathogens Rhizoctonia solani Kühn [Thanatephorus cucumeris (A. B. Frank) Donk], and Pythium ultimum Trow. Susceptibility rating was based on a scale of 1 to 6 where 1 = no symptoms and 6 = dead. Variation was found among A-genome accessions in response to R. solani and P. ultimum, but none were highly resistant to these pathogens. As a group, the A-genome cottons were more susceptible to the pathogens than the G. hirsutum control.Abbreviations STV-A G. hirsutum Stoneville 506 with agar only - STV-NP G. hirsutum Stoneville 506 with non-pathogenic isolate - STV-P G. hirsutum Stoneville 506 with pathogenic isolate - A₁ G. herbaceum - A₂ G. arboreum - GRIN Genetic Resources Information Network     

Simple sequence repeats marker polymorphism in emmer wheat (<Emphasis Type="Italic">Triticum dicoccon</Emphasis> Schrank): Analysis of genetic diversity and differentiation

Genetic diversity was investigated in 73 accessions of emmer wheat (Triticum dicoccon Schrank) from 11 geographical regions using a set of 29 simple-sequence repeat (SSR or microsatellite) markers, representing at least two markers for each chromosome. The SSR primers amplified a total of 357 different alleles with an average of 12.31 alleles per locus. The number of fragments detected by each primer ranged between 6 (Xgwm1066) and 21 (Xgwm268). Null alleles were detected in nine of the 29 primers used. A high level of gene diversity index was observed. Across the 29 primers, gene diversity ranged from 0.60 (Xgwm46) to 0.94 (Xgwm655), with a mean of 0.82. There was a highly significant correlation (r=0.882; p<0.01) between gene diversity index and the number of loci, showing the number of loci per se is a strong indicator of diversity. Analysis of genetic diversity within and among eleven geographical regions revealed most of the genetic diversity of the total sample resided within regions. The coefficient of gene differentiation (Gst = 0.27) showed that the genetic variation within and among the 11 geographical regions was 73 and 27%, respectively. High value of mean number of alleles per locus was found in Iran (4.86) followed by Morocco (4.10) and Armenia (4.03). On the contrary, lower mean number of alleles per locus was detected in Yemen (2.83). The average gene diversity index across regions ranged from 0.52 (Slovakia) to 0.67 (Morocco) with an average of 0.60. Multivariate techniques of principal component analysis and clustering were employed to examine genetic relationship among the 73 emmer wheat accessions vis-à-vis geographical regions of collections. The genetic distance coefficients for all possible 55 pairs of regional comparisons ranged from 0.63 (between Iran and Armenia, Georgia and Azerbaijan, Georgia and Slovakia) to 0.97 (between Morocco and Yemen, Spain and Georgia, and Turkey and Iran) with a mean of 0.82. From the PCA results, a two dimensional plot of PC1 versus PC2 was constructed. The scatter plot of the first two principal components which explained altogether 27% of the total variation depicted the presence of a clear pattern of geographical differentiation except in few cases like accessions from Caucasian region. Similar pattern of genetic relationships among accessions was observed in cluster analysis. The study provided genetic information of emmer wheat in relation to geographical regions of origin. The information could be utilized in crop improvement, germplasm conservation programs, and in further investigation.     

Genetic Diversity Among Traditional Ethiopian Highland Maize Accessions Assessed by Simple Sequence Repeat (SSR) Markers

Over the past three centuries, maize has become adapted to complex environmental conditions in the highlands of Ethiopia. We analyzed 62 traditional Ethiopian highland maize accessions, using 20 simple sequence repeat (SSR) markers and 15 morphological traits, to assess genetic diversity and relationships among these accessions and to assess the level of correlation between phenotypic and genetic distances. The accessions varied significantly for all of the measured morphological traits. The average number of alleles per locus was 4.9. Pair-wise genetic dissimilarity coefficients ranged from 0.27 to 0.63 with a mean of 0.49. Ward minimum variance cluster analysis showed that accessions collected from the Northern agroecology were distinct from the Western and Southern agroecologies. However, there was no differentiation between the Western and Southern accessions. This suggested gene flow between these regions. The relationship between morphological and SSR-based distances was significant and positive (r = 0.43, p = 0.001). The high genetic diversity observed among these set of accessions, suggests ample opportunity for the development of improved varieties for different agroecologies of Ethiopia. From conservation perspective, sampling many accessions from all agroecologies would be an effective way of capturing genetic variation for future collections and conservation.     

On the specific status of Gossypium lanceolatum Todaro

Summary Gossypium lanceolatum comprises a group of laciniate-leaved commensal cottons from the Mexican states of Oaxaca and Guerrero. This geographically restricted, morphologically distinct group of perennial cottons has been considered conspecific with G. hirsutum, with which it is sympatric. In addition to its questionable specific status, G. lanceolatum has added importance because it represents the focal point of an hypothesis that New World tetraploid Gossypium have a polyphyletic origin—an hypothesis that conflicts with the more widely accepted view that New World tetraploid Gossypium have a monophyletic origin. To reassess the systematic and genetic relationships between G. lanceolatum and G. hirsutum, historical data were reconsidered in the context of recently published molecular marker based data. Chloroplast and nuclear DNA markers fail to discriminate G. lanceolatum from G. hirsutum, uniting both into a single phylogenetic lineage. A new analysis of allelic variability at 50 allozyme loci in 11 G. lanceolatum and 527 G. hirsutum accessions demonstrates that G. lanceolatum has no unique alleles relative to G. hirsutum. Genetic identity estimates were uniformly high (> 0.96) among G. lanceolatum and geographically adjacent, mainland Mesoamerican groups of G. hirsutum accessions. Multivariate analyses demonstrated that G. lanceolatum is genetically embedded within geographically adjacent populations of G. hirsutum. These data, in conjunction with the complete interfertility between the two taxa and previous evidence for conspecificity, lead to the conclusion that G. lanceolatum does not warrant specific status. Rather, it is more properly recognized as a locally developed, domesticated form of G. hirsutum, i.e., G. hirsutum race palmeri.     

The Genetic Diversity and Similarities Among <Emphasis Type="Italic">Kengyilia</Emphasis> Species Based on Random Amplified Microsatellite Polymorphism (RAMP)

The genetic diversity and similarities among 32 Kengyilia accessions, distributed to 14 species and one variety were analyzed by using random amplified microsatellite polymorphism (RAMP) markers. Of the 160 RAMP primer combinations tested, 40 (25%) produced polymorphic and clear bands. A total of 264 bands were produced by 40 primer combinations, among which 231 out of 264 bands (87.5%) were polymorphic. Two to 11 polymorphic bands could be amplified from each primer combination, with an average of 5.8 bands. The data of 264 bands were used for RAMP assay. By NTSYS-pc program, genetic similarity coefficients were generated and dendrogram was constructed using UPGMA. The genetic similarity coefficients ranged from 0.477 to 0.965 with the mean of 0.714. The results showed as follows: (1) distinct genetic differences were present among the different species; (2) the different accessions in a species were clustered together, respectively, which had larger genetic similarities and closer relations; (3) the species with similar morphological characters and the species from the same areas or neighboring geographical regions were clustered together; (4) the lowest genetic similarity was found between K. hirsuta (PI531618) and K. laxiflora (PI531631), while the highest genetic similarity was observed between K. hirsuta (Y2364) and K. hirsuta (Y2368); (5) RAMP results are basically comparable with those obtained from studies on morphology and cytology. It is a useful method for analysis of the genetic diversity and similarities in Kengyilia.     

Determining genetic diversity between lines of <Emphasis Type="Italic">Vigna unguiculata</Emphasis> subspecies by AFLP and SSR markers

AFLP (Amplified Fragment Length Polymorphisms) and SSR (Simple Sequence Repeat) markers were utilized to assess genetic diversity and relatedness between Vigna unguiculata subspecies. Three AFLP primer combinations and 10 SSR primer sets successfully identified closely related accessions, and the presence of heterogeneity in some accessions. AFLP methodology was successful in separating different species of Vigna. However, the level of intra-subspecies variation was as great as was the interspecies variation with both marker methods. The number of markers employed was insufficient to successfully group the subspecies into distinct clades.     

Sampling a Core Collection of Island Cotton (Gossypium barbadense L.) Based on the Genotypic Values of Fiber Traits

A genetic model, including effects of environments, genotypes, and genotype by environment interaction, was employed to analyze five fiber traits of Island cotton (Gossypium barbadense L.). Genotypic values of 304 accessions were predicted by the adjusted unbiased prediction (AUP). Genetic similarities between different accessions were measured by Mahalanobis distances based on genotypic values. Appropriate sampling strategies, linkage rules in stepwise clustering, and sampling proportion were evaluated. To form a core collection of Island cotton, 60 accessions were sampled by the deviation sampling strategy combined with single linkage rule of hierarchical clustering. The genetic variation and structure captured by the core collection were examined in means, variances, ranges and coefficients of variation, correlation coefficients of quantitative traits, and the accessions distribution plotted by first two principal components between two collections. It was showed that the initial collection was well represented by the core collection for exploiting the Island cotton germplasm. These authors contributed equally to this work.     

Molecular diversity of Omani wheat revealed by microsatellites: I. Tetraploid landraces

Results of archaeological studies indicate a millennia-old cultivation history for wheat (Triticum spp.) in Oman. However, in spite of numerous collection surveys and efforts for phenotypic characterization of Omani wheat landraces, no attempts have been made using molecular tools to characterize this germplasm. To fill this gap, 29 microsatellite markers revealing 30 loci were used to study the genetic diversity of 38 tetraploid wheat landrace accessions comprising the species T. dicoccon, T. durum and T. aethiopicum. A total of 219 alleles were detected whereby the number of alleles per locus ranged from 2 to 16 with an average number of 7.1 alleles per locus. The highest number of alleles occurred in the B genome with on average 7.9 alleles per locus as compared to the A genome with 6.5 alleles per locus. Heterogeneity was detected for all microsatellites except for GWM 312, GWM 601 and GWM 192B with an average heterogeneity over all primers and lines of 14.4%. Approximately 10% of the accessions contained rare alleles with an average allele frequency <4%. Gene diversity across microsatellite loci ranged from 0.26 to 0.85. The pairwise comparison of genetic similarity ranged from 0.03 to 0.91 with an average of 0.2. Cluster analysis revealed a clear separation of the two species groups T. dicoccon versus T. durum and T. aethiopicum. Within the species clusters regional patterns of subclustering were observed. Overall, this study confirmed the existence of a surprisingly high amount of genetic diversity in Omani wheat landraces as already concluded from previous morphological analyses and showed that SSR markers can be used for landraces’ analysis and a more detailed diversity evaluation.     

The Genetic Diversity Among Leymus Species Based on Random Amplified Microsatellite Polymorphism (RAMP)

The genetic diversity and similarities among 40 accessions of Leymus Hochst., distributed in 19 species and 1 subspecies, were analyzed by using random amplified microsatellite polymorphism (RAMP) markers. Of the 120 RAMP primer combinations tested, 24 (20%) produced polymorphic and clear bands. A total of 192 bands were amplified by 24 primer combinations, among which 179 (93.23%) bands were found to be polymorphic. Three to thirteen polymorphic bands were amplified by each primer combination, with an average of 7.64 bands. The data of 192 RAMP bands were used to generate Jaccard's similarity coefficients and to construct a dendrogram by means of UPGMA in the NTSYS-pc computer program. The genetic similarity coefficients ranged from 0.10 to 0.73 with the mean of 0.34. The results showed as follows: (1) Distinct genetic differences were present among the different species; (2) The different accessions in a species were clustered together, respectively, which had larger genetic similarities and closer relations; (3) The species with similar morphological characters and the species from the same areas or neighboring geographical regions were clustered together; (4) RAMP results are basically comparable with those obtained from studies on morphology. It is a useful method for analysis of the genetic diversity and similarities in Leymus.     

Temporal variation of diversity in Italian durum wheat germplasm

The aim of this work is to analyse the temporal change of genetic diversity in Italian durum wheat germplasm. The germplasm deployed in this study (158 accessions), belonging to 5 different historical classes, was characterised for its microsatellite and gliadin markers. The level of genetic diversity (He), based on gliadin and SSR markers results – on average – greater in indigenous landraces present in Italy before 1915, with the exception of pure line material which had been selected from landraces (showing highest level of heterozigosity for gliadin markers). Genotypes obtained from crosses or mutagenesis (referring to the 1950–1960 period) along with those resulting from crosses between CIMMYT lines and old materials (1970s and beyond) were also genetically more diverse. Forty-nine percent of indigenous landraces were genetically heterogeneous. Nine out of 53 landrace accessions were able to capture 4 different SSR private alleles. It is speculated that the reduction of allele richness is an indicator of the genetic erosion of the pre-breeding germplasm and it is pointed out that the implementation of appropriate methods of genetic conservation of this germplasm is a priority for breeding and food safety.     

A wide range of genetic diversity in pear (<Emphasis Type="Italic">Pyrus ussuriensis</Emphasis> var. <Emphasis Type="Italic">aromatica</Emphasis>) genetic resources from Iwate,Japan revealed by SSR and chloroplast DNA markers

Iwateyamanashi (Pyrus ussuriensis var. aromatica) is one of the Pyrus species which grows wild in Japan. The number of Iwateyamanashi trees has been decreasing, so conservation and evaluation is urgently needed. Over 500 accessions of Pyrus species collected from Iwate in northern Tohoku region are maintained at Kobe University as an Iwateyamanashi germplasm collection. In order to investigate the genetic diversity, five SSR (simple sequence repeat) markers, developed from Japanese and European pear were examined for 86 Pyrus individuals including 58 accessions from Iwate. These SSR loci could discriminate between all the Iwate accessions except for 10 that bear seedless fruit, as well as determine the genetic diversity in Iwateyamanashi germplasms. High levels of variation were detected in 41 alleles and the mean observed heterozygosity across 5 loci was 0.50 for the Iwate accessions. Seedless accessions sharing identical SSR genotype with the local pear variety “Iwatetanenashi” were supposed to have been propagated vegetatively via grafting. In an UPGMA phenogram, Japanese pear varieties (P. pyrifolia) were clustered into two groups with some Iwate accessions including seedless ones. Another 38 Iwate accessions were not clustered clearly, and there was no clear relationship between these accessions and geographical distribution or morphological characters. Allele frequency revealed that the Iwate accessions were genetically more divergent than the Japanese pear varieties. Most Japanese pears possessed a 219 bp deletion at a spacer region between the accD and psaI genes in the chloroplast DNA (cpDNA), but other Pyrus species and two Iwateyamanashi trees did not. In the Iwate accessions, 79.3% had a deletion type cpDNA and others had a standard type cpDNA without deletion. These results are indicative of the wide range of genetic diversity in the Iwate accessions which include Japanese pear varieties. A combination of SSR and cpDNA analyses revealed high heterogeneity in Iwateyamanashi and coexistence of Iwateyamanashi and hybrid progeny with P. pyrifolia. These could be reasons for the wide range of continuous morphological variation described previously.     

Genetic diversity and phylogenetic relationship of <Emphasis Type="Italic">Tadehagi</Emphasis> in southwest China evaluated by inter-simple sequence repeat (ISSR)

There are many valuable Tadehagi accessions in southwest China, but it is unknown that the genetic diversity and phylogenetic relationship of these Tadehagi resources. This report is the first study in which 41 primers of inter-simple sequence repeat (ISSR) were used to assess the genetic diversity of 36 Tadehagi accessions from 3 provinces in the southwest of China. Totally, 30 usable ISSR primers detected 163 polymorphic bands among the 36 accessions, which suggested high utility of ISSR primers in the genetic analysis of Tadehagi accessions. Genetic similarity coefficients among all of the accessions ranged from 0.54 to 0.92 with the average of 0.79 based on the ISSR data, indicating high level of genetic variation in Tadehagi resources from the southwest of China. As for the 3 population, Hainan population had the maximum average genetic similarity coefficients of 0.81, while similarity coefficient of Guangxi and Yunnan population was 0.75 and 0.74, respectively. All the 36 Tadehagi accessions were divided into 4 groups in the UPGMA dendrogram constructed from genetic similarity coefficients. The Tadehagi accessions from Yunnan and Guangxi provinces showed more genetic variation and occupied the bottom of the dendrogram. On the contrary, those from Hainan Province had less genetic variation and clustered in the middle and top of the dendrogram. The information on the genetic diversity and phylogenetic relationship from this study is propitious to construct a core germplasm collection and develop novel Tadehagi cultivars with desired economic traits.     

Analysis of genetic diversity in Indian robusta coffee genepool (<Emphasis Type="Italic">Coffea canephora</Emphasis>) in comparison with a representative core collection using SSRs and AFLPs

Genetic diversity among 40 accessions (Coffea canephora) of robusta coffee genepool available in India was determined in comparison with 14 representative samples from a C. canephora core collection and three accessions of C. congensis, using amplified fragment length polymorphism (AFLP) and simple sequence repeats (SSR) markers. Both these molecular approaches were able to generate unique fingerprints for each of the accessions analysed. All the 12 SSR primers used in the present study were found polymorphic, with an average of six alleles per primer pair. Comparative analysis revealed the higher amount of diversity in representatives from a core collection than in the Indian genepool. Moreover, a total of 205 polymorphic AFLP bands were scored in all the 57 accessions analysed. The genetic relationship among 57 accessions was compared on the basis of SSR and AFLP polymorphisms. Genetic similarity dendrograms showed high correlation between the two marker systems. This study clearly established the high amount of diversity present in core samples, which is not represented in Indian genepool. Furthermore, the three accessions of C. congensis did not exhibit any significant diversity from other robusta accessions supporting the school of thought that C. congensis forms a biotype of C. canephora. The potential use of SSRs and AFLP markers in genetic diversity analysis for better ex situ management and also for exploitation of diversity in breeding programmes is discussed.     

Cytoplasmic diversity of the cotton genus as revealed by chloroplast microsatellite markers

The diversity of chloroplast genomes has played an important role, as have those of nuclear and mitochondrial genomes, in the evolution of plants. The sequences of the chloroplast genome supply unsubstituted information for genome analysis. In order to understand the genetic differentiation and relationship of cotton species, we investigated the cytoplasmic diversity of chloroplast genomes in 41 Gossypium accessions with 75 chloroplast simple sequence repeat (cpSSR) markers. The markers were developed from reference sequences of the chloroplast genomes of G. hirsutum and G. barbadense and covered approximately 12.6 kb. Among the 75 markers, 50 were polymorphic, with polymorphism information content values ranging from 0.11 to 0.88. Analyses of the dataset demonstrated that single copy regions were much more informative than inverted repeat regions. The non-coding sequences were well differentiated among these species. For some common cpDNA haplotypes, the E-genome species that may be the oldest of the extant cotton species was deduced. The differentiation of A-genome species lagged behind that of AD-genome species. Neither G. herbaceum nor G. arboreum was the cytoplasmic donor of tetraploid species, strongly suggesting that AD genomes originated from an extinct ancestor of modern A-genome species. We speculate that the genetic differentiation of the chloroplast genome of each cotton species resulted from the dispersal of that species and its adaptations to local ecological conditions. These cpSSR markers provided valuable information to reveal the diversity and differentiation of cotton during evolution.     

Analysis of Genetic Diversity in the Brassica napus L. Gene Pool Using SSR Markers

Genetic diversity throughout the rapeseed (Brassica napus ssp. napus) primary gene pool was examined by obtaining detailed molecular genetic information at simple sequence repeat (SSR) loci for a broad range of winter and spring oilseed, fodder and leaf rape gene bank accessions. The plant material investigated was selected from a preliminary B. napus core collection developed from European gene bank material, and was intended to cover as broadly as possible the diversity present in the species, excluding swedes (B. napus ssp. napobrassica (L.) Hanelt). A set of 96 genotypes was characterised using publicly available mapped SSR markers spread over the B. napus genome. Allelic information from 30 SSR primer combinations amplifying 220 alleles at 51 polymorphic loci provided unique genetic fingerprints for all genotypes. UPGMA clustering enabled identification of four general groups with increasing genetic diversity as follows (1) spring oilseed and fodder; (2) winter oilseed; (3) winter fodder; (4) vegetable genotypes. The most extreme allelic variation was observed in a spring kale from the United Kingdom and a Japanese spring vegetable genotype, and two winter rape accessions from Korea and Japan, respectively. Unexpectedly the next most distinct genotypes were two old winter oilseed varieties from Germany and Ukraine, respectively. A number of other accessions were also found to be genetically distinct from the other material of the same type. The molecular genetic information gained enables the identification of untapped genetic variability for rapeseed breeding and is potentially interesting with respect to increasing heterosis in oilseed rape hybrids.