Having knowledge on genetic similarity and DNA profile of potato genotypes facilitates a breeder's decision for parent selection and provides accurate variety identification. Fingerprinting and identification of genetic similarity among 151 potato genotypes were achieved using an inter-primer-binding sites (iPBS) retrotransposon marker system. Our study is the first application of iPBS markers for fingerprinting and distinguishing large numbers of Solanum tuberosum genotypes. Initially, 16 potato genotypes were screened using 45 iPBS retrotransposon markers to identify polymorphisms. Seventeen of these primers were selected for fingerprinting the whole set of accessions due to strong, reproducible and polymorphic bands. The 17 iPBS primers produced 290 scorable bands of which 224 were polymorphic. The number of bands per primer ranged from 10 to 26 with an average of 17.1. The number of polymorphic bands per primer was between 6 and 21. The polymorphism percentage per primer ranged from 46.2 to 100.0% with an average of 77.2% per primer. The mean polymorphism information content (PIC) values of iPBS primers varied from 0.12 to 0.31 per primer. Genetic similarity based on Jaccard's coefficient of potato genotypes ranged from 0.61 to 0.93 with an average of 0.73. The data produced herein may be used for selection of appropriate parents and variety description in the future. The findings of the present study suggest that iPBS retrotransposons are powerful and easy DNA markers for fingerprinting the large samples of potato germplasm.

DNA fragment analysis, based on amplification of intersimple sequence repeats by the polymerase chain reaction (ISSR-PCR), was used to assess genetic relationships of 217 U.S. accessions of common cocklebur. Twenty-four polymorphic markers were generated from six primers. Analysis of genetic similarity by clustering procedures resulted in separation of the accessions into two main clusters. Accessions within these two clusters were designated as either northern or southern genotypes. Forty-four of 48 accessions analyzed from Washington, Michigan, Iowa, and Ohio were northern genotypes, whereas 67 of 68 accessions analyzed from Mississippi, Arkansas, South Carolina, and North Carolina were southern genotypes. Accessions from Kansas, Missouri, and Illinois included 40 and 56 northern and southern genotypes, respectively, indicating a transition zone. In Illinois, accessions collected from northern and southern counties tended to be northern and southern genotypes, respectively. We conclude that much of the genetic variation among U.S. common cocklebur accessions is distributed along a latitudinal gradient.

Focusing on 116 bread wheat landraces, this study investigated high molecular weight glutenin allele polymorphism, gene diversity, genetic variation and linkage disequilibrium (LD) in Glu-1 loci. To identify gluten alleles, sodium dodesyl sulphate-polyacrylamide, gel electrophoresis was used and for statistical analyses POPGENE software was employed. The results indicated that average genetic variation (h) was the highest in Glu-B1 (0.6421) and the lowest in Glu-A1 locus (0.4548); genetic similarity ratio (I) was the highest in Glu-B1 (1.4170); the highest average genetic diversity (Ht) was observed in Glu-B1 (0.6575) and the lowest diversity was observed in Glu-A1 (0.4558). It was also observed that genetic diversity in Glu-1 locus was largely due to intra-population variations. Inter-population gene flow was also calculated as 4.0051. Marmara and Southeastern Anatolia regions, the results further indicated, had the highest (2.8691) and lowest (0.1694) heterozygosity. Genetic erosion risk for Turkish bread wheat landraces was also seen to be high. Considering the mutual analyses of subunits of nationwide wheat landraces, it is possible to speculate about a limited migration between the landraces. LD of the landraces was largely because of this limited migration and/or epistatic natural selection. Since Turkey is known as the gene centre for major cereals including wheat, barley, rye and oat, where they diversified and spread throughout the world, studying the gluten allele diversity of Turkish bread wheat landraces is important. In addition, this study has revealed the applicability of LD, and neutrality tests to gluten protein diversity for the first time.

There are three native varieties of edible yams (Dioscorea japonica Thunb.) in Taiwan, but germplasm has been collected from only a few. To assess the genetic diversity of 99 accessions collected from four geographically diverse regions, inter-simple sequence repeat (ISSR) DNA markers were analysed, and 90.2% of the polymorphic markers in these accessions were found. Genetic similarity among accessions ranged from 30.8 to 74.4%, averaging 48.4%. Cluster analyses revealed four main clusters plus one outlier (Dioscorea alata L.). The varieties oldhamii and pseudojaponica were separated into different clusters and var. japonica was grouped with both varieties. Since var. japonica was found to be genetically similar to var. oldhamii and var. pseudojaponica, we suggest that var. japonica is a hybrid or intermediate variety between the two varieties. Molecular analysis of variance results indicated that variation within counties (95.94%) was predominantly greater than variation among counties (3.63%) and among regions (0.43%). Overall, gene flow (Nm= 0.970) estimated from genetic differentiation (Gst= 0.340) suggests that gene flow among regions is relatively high. The highest genetic diversity (H= 0.191) and Shannon's index (I= 0.312), and a high gene flow (Nm= 3.926) of germplasm in the northern region suggest that this region is a possible centre of dispersal and domestication of yams in Taiwan. This study provided valuable information for germplasm collection and genetic improvement.

The stagnation of sorghum grain yields worldwide and utilization of inbred lines by public and private organizations (multinational seed companies) warrant the understanding of genetic diversity present in inbred lines. The objectives of this study were (1) to compare morphological and molecular diversity analysis and (2) to identify heterotic pools from the genotypes evaluated. Sixty-five rainy-season elite lines were evaluated during the 2006 and 2007 rainy seasons, and 15 post-rainy-season genotypes in the 2003 and 2004 post-rainy seasons for their distinctiveness, uniformity and stability at the Directorate of Sorghum Research, Hyderabad, India. Ninety-three genotypes (ten rainy-season B lines, 13 rainy-season R lines, 36 rainy-season varieties, seven rainy-season hybrids, ten forage varieties and 17 post-rainy-season genotypes) were evaluated using 48 simple sequence repeat (SSR) markers that are uniformly distributed over the sorghum genome. From the 93 genotypes analysed, 310 alleles were observed, with an average of 6.5 alleles per locus. A high level of polymorphism (mean 97%) was detected. A significant positive correlation (r = 0.463; P = 0.001) between genetic similarities and morphological similarities was obtained. Unlike previous reports, both methods clearly distinguished B lines, R lines, rainy-season varieties, post-rainy-season varieties and forage varieties. Forage and post-rainy-season varieties present a higher diversity of 60%. This could be because the post-rainy-season varieties are developed from local landraces and forage genotypes from crosses such as Sorghum bicolor × Sudan grass. Herein, we further discuss the grouping of elite genotypes into different heterotic pools.

Pennisetum purpureum Schum. (napiergrass) is a perennial grass used for forage especially in South America and Africa. Over the last 30 years, a USDA–ARS nursery containing accessions collected from all over the world has been established in Tifton, Georgia. The study reported here was conducted to assess the molecular genetic variation and genetic relatedness among 89 accessions from the Tifton nursery using amplified fragment length polymorphism markers, morphological data and ploidy level. Using 218 polymorphic markers from eight selective primer combinations, the 89 accessions were clustered into five groups using a principal components analysis and a dendrogram based on Dice similarity estimates and unweighted pair group method with arithmetic average clustering. These five groups include three groups collected from Kenya, a group from Puerto Rico, and accessions derived from the cultivar Merkeron. This research provides the first molecular characterization of the Tifton nursery, displays the relationships between accessions, and provides potential heterotic groups for napiergrass and pearl millet (Pennisetum glaucum (L.) R. Br.) breeding improvement.

Morphologically, early immature stages of the economically important pest called screwworms, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), and non-pest secondary screwworms, Cochliomyia macellaria (Fabricius) (Diptera: Calliphoridae), are nearly indistinguishable. Correct identification is crucial to the ongoing eradication and exclusion program protecting the United States, Mexico and Central America from reinvasion of screwworms persistent in South America and the Caribbean. Amplified fragment length polymorphism (AFLP) polymerase chain reaction was used to differentiate populations of C. hominivorax and to discriminate them from C. macellaria. Ten primer pairs screened for interspecific discrimination of C. hominivorax from C. macellaria showed 52 discrete bands, allowing the two species to be readily distinguished; divergent branches on resulting dendrograms showed 100% bootstrap support. C. macellaria populations grouped at the 92% level; C. hominivorax populations grouped at the 68% level. Of the 52 bands, seven were monomorphic for both species, 22 were specific to C. macellaria, ten were present only in C. hominivorax and the remaining 13 bands differentiated C. hominivorax populations. Separate studies using ten strains of C. hominivorax showed a higher level of genetic similarity within than between populations. Analyses using 72 bands (19 monomorphic bands, 53 bands grouped all ten strains at the 58% similarity level) resolved seven mutant strains from Mexico (85% similarity level); all ten strains were resolved at the 72% similarity level. Diagnostic bands were identified for species and strain identification. We conclude that AFLP can be a valuable tool for studies of interspecific and intraspecific genetic variation in screwworm populations.

Seven community complexes have been described across sub-Antarctic Marion Island, amongst these fellfield that comprise low plant cover dominated by Azorella selago Hook. f. Azorella is considered a keystone species since it forms nutrient rich environments for microarthropod communities and epiphytic plants. Two distinct growth forms typify Azorella, namely discrete cushions and continuous mats. Whether these continuous mats normally consist of a single large cushion individual, or whether several individual plants merge, interdigitating to form a continuous area, remains unclear. As such, it is important to obtain some measure of Azorella growth dynamics before embarking on phylogeographic studies. Previous genetic studies indicated that several microarthropod species are significantly substructured across Marion Island, but it remains unclear whether similar subdivisions characterize Azorella. We used chloroplast sequence data (trnH-psbA) and amplified fragment length polymorphism (AFLP) to investigate these questions. No sequence variation characterized the trnH-psbA region in Azorella across Marion Island. In contrast, the AFLP results indicated that an A. selago mat comprises multiple individuals. We argue that mats can be formed through at least two processes namely fragmentation, where parts of the cushion plant die off creating open areas for the establishment of different individuals and/or high density of interdigitating individuals merging to form the mat. Fragment data further indicated significant substructure for Azorella across Marion Island (FST = 0.101, P = 0.01) and we attribute this to past vicariance.

Genetic relationships among elite celeriac varieties and celeriac accessions conserved in genebanks are generally unknown. The objective of this study was to use amplified fragment length polymorphism (AFLP) markers and morphological characterization to identify material that could be of use in celeriac breeding. Genetic relationships were estimated in 34 elite celeriac varieties bred in Europe and 28 celeriac accessions conserved at the German genebank. Two varieties of celery, two varieties of leaf celery and three genebank accessions of wild Apium species were additionally analysed. Fifteen EcoRI/MseI-based AFLP primer combinations were used. Polymorphic AFLP fragments were scored for calculation of Jaccard's coefficient of genetic similarity (GS). Morphological distances (MD) were determined based on 11 morphological traits. Average GS estimate in elite germplasm (GS=0.90) was higher than in exotic germplasm (GS=0.80). An AMOVA (analysis of molecular variance) revealed that a high proportion of variation was due to variation within elite celeriac varieties and genebank accessions. Although GS and MD matrices were poorly correlated (r=0.22), UPGMA (unweighted pair group method using arithmetic averages) cluster analyses revealed clear genetic groupings of celeriac germplasm, which was supported by morphological traits. Elite, moderately bred and exotic varieties formed distinct clusters, indicating that only a part of the available genetic diversity in celeriac germplasm has been exploited in breeding. Distinct Apium species might be useful for the introgression of new genes into cultivated celeriac material. Broadening of celeriac collections in genebanks and detection of new genetic resources are vital for improvements in celeriac breeding.