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  • Microsatellite  (6)
  • DNA fingerprinting  (1)
  • DNA typing  (1)
  • Genetic similarity  (1)
  • 1
    ISSN: 1432-2242
    Keywords: Simple sequence repeats ; Microsatellite ; Molecular marker ; Seashore paspalum ; Germ plasm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A size-fractionated TaqI genomic library of seashore paspalum (Paspalum vaginatum Swartz) was screened for the presence of (GA) n and (CA) n simple sequence repeats (SSRs). A total of 54 clones with a positive signal were detected among 13,000 clones screened. Forty-seven clones having repeats of n⩾ 3 were identified, of which 85% were perfect, 13% were imperfect and 2% were compound repeat sequences. Five of ten primer pairs synthesized to amplify selected loci resulted in a product in the expected size range and were subsequently used to examine SSR polymorphisms among 46 ecotypes of P. vaginatum. The number of alleles resolved on agarose or polyacrylamide gels were similar and ranged from 6 to 16 with an average of 14 per locus. Phenetic analysis of SSR polymorphisms revealed genetic relationships among the P. vaginatum ecotypes that were in general agreement with relationships determined previously by RAPD analysis of the same plant materials. Further screening of the genomic library did not identify (AT) n , trimeric or tetrameric repeats. Hybridization of an (ATT)8 oligonucleotide probe to genomic DNA isolated from I. batatas, E. coli, Citrullis lanatus and P. vaginatum suggested that the P. vaginatum genome contained significantly fewer ATT repeats than either the I. batatas or C. lanatus genome.
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  • 2
    ISSN: 1432-2242
    Keywords: Key words DNA marker ; Genetic analysis ; Genetic diversity ; Genotyping ; Microsatellite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The application of simple sequence repeat (SSR) genotyping for the characterization of genetic variation in crop plants has been hindered by ready access to useful primer pairs and potentially limited conservation of the repeat sequences among related species. In this phase of work, we report on the identification and characterization of SSRs that are conserved in Brassica napus L. (rapeseed) and its putative progenitors, B. oleracea L. (cabbage, and related vegetable types) and B. rapa (vegetable and oil types). Approximately 140 clones from a size-fractionated genomic library of B. napus were sequenced, and primer pairs were designed for 21 dinucleotide SSRs. Seventeen primer pairs amplified products in the three species and, among these, 13 detected variation between and within species. Unlike findings on SSR information content in human, no relationship could be established between the number of tandem repeats within the target sequence and heterozygosity. All primer pairs have been designed to work under identical amplification conditions; therefore, single-reaction, multiplex polymerase chain reaction (PCR) with these SSRs is possible. Once moderate numbers of primer pairs are accessible to the user community, SSR genotyping may provide a useful method for the characterization, conservation, and utilization of agricultural crop diversity.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 98 (1999), S. 895-902 
    ISSN: 1432-2242
    Keywords: Key words AFLP (amplified fragment length polymorphism) ; Bermudagrass (Cynodon spp.) ; DNA fingerprinting ; Semi-automated fluorescence-based genotyping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Bermudagrasses (Cynodon spp.) are major turfgrasses for home lawns, public parks, golf courses and sport fields, and are widely adapted to tropical and warmer temperate climates. Morphological and physiological characteristics are not sufficient to differentiate some bermudagrass genotypes because the differences between them are often subtle and subject to environmental influence. In this study, a DNA-typing technique, amplified fragment length polymorphism (AFLP), was used to differentiate bermudagrass genotypes and to explore their genetic relationships. Twenty seven bermudagrass cultivars and introductions, mostly from the Coastal Plain Experiment Station in Tifton, Ga., were assayed by the radioactive (32P) and the fluorescence-labeled AFLP methods. The AFLP technique produced enough polymorphism to differentiate all 27 bermudagrass genotypes, even the closely related ones. An average of 48–74 bands in the 30–600-bp size range was detected by the 32P-labeled AFLP method. The results indicated that most of the 14 primer combinations tested in this study could be used to distinguish bermudagrass genotypes, and that some single primer-pairs could differentiate all 27 of them. To test the reliability and reproducibility of the AFLP procedure, three DNA isolations (replications) of the 27 bermudagrass genotypes were assayed using five primer pairs. Only 0.6% of the bands were evaluated differently among the three replications. One replication of one genotype (which was most likely a planting contaminant) was grouped in an unexpected cluster using the Unweighted Pair Group Mean Average (UPGMA) method. A one- or two-band difference in scoring did not change the clustering of genotypes or the replications within genotypes. The 27 genotypes were grouped into three major clusters, many of which were in agreement with known pedigrees. Trees constructed with different primer combinations using 32P- and fluorescence-labelling formed similar major groupings. The semi-automated fluorescence-based AFLP technique offered significant improvements on fragment sizing and data handling. It was also more accurate for detection and more efficient than the radioactive labelling method. This study shows that the AFLP technique is a reliable tool for differentiating bermudagrass genotypes and for determining genetic relationships among them.
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  • 4
    ISSN: 1432-2242
    Keywords: Microsatellite ; Germplasm ; Genetic resources ; Genetic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simple sequence repeats (SSRs), also known as microsatellites, are highly variable DNA sequences that can be used as markers for the genetic analysis of plants. Three approaches were followed for the development of PCR primers for the amplification of DNA fragments containing SSRs from sorghum [Sorghum bicolor (L.) Moench]: a search for sorghum SSRs in public DNA databases; the use of SSR-specific primers developed in the Poaceae species maize (Zea mays L.) and seashore paspalum grass (Paspalum vaginatum Swartz); and the screening of sorghum genomic libraries by hybridization with SSR oligonucleotides. A total of 49 sorghum SSR-specific PCR primer pairs (two designed from GenBank SSR-containing sequences and 47 from the sequences of genomic clones) were screened on a panel of 17 sorghum and one maize accession. Ten primer pairs from paspalum and 90 from maize were also screened for polymorphism in sorghum. Length polymorphisms among amplification products were detected with 15 of these primer pairs, yielding diversity values ranging from 0.2 to 0.8 with an average diversity of 0.56. These primer pairs are now available for use as markers in crop improvement and conservation efforts.
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  • 5
    ISSN: 1432-2242
    Keywords: DNA typing ; Genetic similarity ; Genetic structure ; Genetic resource conservation ; Vegetable and forage cole crops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Effective conservation and the use of plant genetic resources are essential for future agricultural progress. Critical to this conservation effort is the development of genetic markers which not only distinguish individuals and accessions but also reflect the inherent variation and genetic relationships among collection holdings. We have examined the applicability of the random amplified polymorphic DNA (RAPD) assay for quick, cost-effective, and reliable use in addressing these needs in relation to collection organization and management. Twenty-five decamer oligonucleotide primers were screened individually with a test array composed of individuals representing a range of genetic relationships in Brassica oleracea L. (vegetable and forage cole crops). Over 140 reproducible, polymorphic fragments were generated for study. Each individual of the test array exhibited a unique molecular genotype and composites specific for accessions and botanical varieties could be established. An analysis of similarity based on amplified DNA fragments reflected the known genetic relationships among the selected entries. These results demonstrated that RAPD markers can be of great value in gene bank management for purposes of identification, measurement of variation, and establishment of genetic similarity at the intraspecific level.
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  • 6
    ISSN: 1432-2242
    Keywords: DNA marker ; Genetic analysis ; Genetic diversity ; Genotyping ; Microsatellite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The application of simple sequence repeat (SSR) genotyping for the characterization of genetic variation in crop plants has been hindered by ready access to useful primer pairs and potentially limited conservation of the repeat sequences among related species. In this phase of work, we report on the identification and characterization of SSRs that are conserved in Brassica napus L. (rapeseed) and its putative progenitors, B. oleracea L. (cabbage, and related vegetable types) and B. rapa (vegetable and oil types). Approximately 140 clones from a size-fractionated genomic library of B. napus were sequenced, and primer pairs were designed for 21 dinucleotide SSRs. Seventeen primer pairs amplified products in the three species and, among these, 13 detected variation between and within species. Unlike findings on SSR information content in human, no relationship could be established between the number of tandem repeats within the target sequence and heterozygosity. All primer pairs have been designed to work under identical amplification conditions; therefore, single-reaction, multiplex polymerase chain reaction (PCR) with these SSRs is possible. Once moderate numbers of primer pairs are accessible to the user community, SSR genotyping may provide a useful method for the characterization, conservation, and utilization of agricultural crop diversity.
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  • 7
    ISSN: 1432-2242
    Keywords: Key words Simple sequence repeat ; Microsatellite ; SSRs ; Maize ; Variety identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The utility of 131 simple sequence repeat (SSR) loci to characterize and identify maize inbred lines, validate pedigree, and show associations among inbred lines was evaluated using a set of 58 inbred lines and four hybrids. Thirteen sets of inbred parent-progeny triplet pedigrees together with four hybrids and their parental lines were used to quantify incidences of scoring that departed from expectations based upon simple Mendelian inheritance. Results were compared to those obtained using 80 restriction fragment length polymorphism (RFLP) probes. Over all inbred triplets, 2.2% of SSRs and 3.6% of RFLP loci resulted in profiles that were scored as having segregated in a non-Mendelian fashion. Polymorphic index content (PIC, a measure of discrimination ability) values ranged from 0.06 to 0.91 for SSRs and from 0.10 to 0.84 for RFLPs. Mean values for PIC for SSRs and RFLPs were similar, approximately 0.62. However, PIC values for nine SSRs exceeded the maximum PIC for RFLPs. Di-repeats gave the highest mean PIC scores for SSRs but this class of repeats can result in “stutter” bands that complicate accurate genotyping. Associations among inbreds were similar for SSR and RFLP data, closely approximating expectations from known pedigrees. SSR technology presents the potential advantages of reliability, reproducibility, discrimination, standardization and cost effectiveness over RFLPs. SSR profiles can be readily interpreted in terms of alleles at mapped loci across a broad range of maize germ plasm. Consequently, SSRs represent the optimum approach for the identification and pedigree validation of maize genotypes compared to other currently available methods.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 96 (1998), S. 272-281 
    ISSN: 1432-2242
    Keywords: Key words Brassica ; Genome conservation ; Microsatellite ; Molecular genetic variation ; Short tandem repeat (STR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Simple-sequence repeats (SSRs) may prove to be valuable descriptors of plant genetic variation, but developing markers for each of many taxa is costly. The applicability of SSR markers may be increased if they can be amplified across taxa. In this study, we examined whether 30 primer pairs designed to amplify single-locus SSRs in Arabidopsis thaliana could be used to amplify marker loci in six Brassica crop species. Most of the pairs amplified multiple fragments in Brassica. In initial assays, 17 pairs generated products that were identified as likely to contain SSRs. Most of these products were similar in size to A. thaliana SSRs; many were variable for product length, and many of the variants were species- or genome-specific. In subsequent hybridization assays, however, not all of the identified Brassica products hybridized to SSR probes. A Brassica product’s length variation and its size similarity to A. thaliana SSRs were not good predictors of whether the product contained repeats. In addition, some products of two-primer reactions hybridized to SSR probes but were the same size as single-primer reaction products, so they may have been amplified by only one primer. In summary, Brassica products amplified by A. thaliana SSR primer pairs may be useful as markers, but additional tests (hybridization, DNA sequencing, and single-primer assays) are necessary in order to determine whether the products contain SSRs and whether they are amplified by one or two primers. The results of this study are consistent with conservation, duplication, and rearrangement between Arabidopsis and Brassica genomes.
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