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  • 11
    Electronic Resource
    Electronic Resource
    Non-Mendelian and skewed segregation of DNA markers in wide crosses of the bean rust fungus,Uromyces appendiculatus (1996)
    Springer
    Current genetics 29 (1996), S. 159-167 
    Details
    ISSN: 1432-0983
    Keywords: Genetic linkage mapping ; Segregation distortion ; RAPD ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The inheritance of DNA markers was investigated in 27 F2 progeny from a single F1 hybrid derived from a wide cross inUromyces appendiculatus. This cross was unusual because asexual spores were used to fertilize sexual fruiting structures. Sixty percent of the DNA markers failed to segregate according to simple Mendelian ratios. Segregation bias was evident, in that F2 progeny inherited on average 91 % of maternal bands and 52% of paternal bands, which deviates significantly from the expected value for each of 75% for dominant markers. Because of these distortions, linkage mapping was not possible with this population. Evaluation of two F1s from a second wide cross, reciprocals obtained by normal fertilization, also showed non-Mendelian inheritance of one of three co-dominant RFLPs and five of six isozyme markers, indicating that the method of crossing was probably not responsible for the abnormal segregation patterns in the first cross. Either genetic incompatibility, similar to that of an interspecific cross, or selection of particular genotypes could explain the genetic anomalies reported here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02221580
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  • 12
    Electronic Resource
    Electronic Resource
    Non-Mendelian and skewed segregation of DNA markers in wide crosses of the bean rust fungus, Uromyces appendiculatus (1996)
    Springer
    Current genetics 29 (1996), S. 159-167 
    Details
    ISSN: 1432-0983
    Keywords: Key words Genetic linkage mapping ; Segregation distortion ; RAPD ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The inheritance of DNA markers was investigated in 27 F2 progeny from a single F1 hybrid derived from a wide cross in Uromyces appendiculatus. This cross was unusual because asexual spores were used to fertilize sexual fruiting structures. Sixty percent of the DNA markers failed to segregate according to simple Mendelian ratios. Segregation bias was evident, in that F2 progeny inherited on average 91% of maternal bands and 52% of paternal bands, which deviates significantly from the expected value for each of 75% for dominant markers. Because of these distortions, linkage mapping was not possible with this population. Evaluation of two F1s from a second wide cross, reciprocals obtained by normal fertilization, also showed non-Mendelian inheritance of one of three co-dominant RFLPs and five of six isozyme markers, indicating that the method of crossing was probably not responsible for the abnormal segregation patterns in the first cross. Either genetic incompatibility, similar to that of an interspecific cross, or selection of particular genotypes could explain the genetic anomalies reported here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002940050031
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  • 13
    Electronic Resource
    Electronic Resource
    Restriction fragment length polymorphism maps and the concept of graphical genotypes (1989)
    Springer
    Theoretical and applied genetics 77 (1989), S. 95-101 
    Details
    ISSN: 1432-2242
    Keywords: RFLPs ; Haplotypes ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary With the advent of high density restriction fragment length polymorphism (RFLP) maps, it has become possible to determine the genotype of an individual at many genetic loci simultaneously. Often, such RFLP data are expressed as long strings of numbers or letters indicating the genotype for each locus analyzed. In this form, RFLP data can be difficult to interpret or utilize without complex statistical analysis. By contrast, numerical genotype data can also be expressed in a more useful, graphical form, known as a “graphical genotype”, which is described in detail in this paper. Ideally, a graphical genotype portrays the parental origin and allelic composition throughout the entire genome, yet is simple to comprehend and utilize. In order to demonstrate the usefulness of this concept, graphical genotypes for individuals from backcross and F2 populations in tomato are described. The concept can also be utilized in more complex mating schemes involving two or more parents. A model that predicts the accuracy of graphical genotypes is presented for hypothetical RFLP maps of varying marker spacing. This model indicates that graphical genotypes can be more than 99% correct in describing a genome of total size, 1000 cM, with RFLP markers located every 10 cM. In order to facilitate the application of graphical genotypes to genetics and breeding, we have developed computer software that generates and manipulates graphical genotypes. The concept of graphical genotypes should be useful in whole genome selection for polygenic traits in plant and animal breeding programs and in the diagnosis of heterogenously based genetic diseases in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292322
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  • 14
    Electronic Resource
    Electronic Resource
    RFLP analysis of the size of chromosomal segments retained around the Tm-2 locus of tomato during backcross breeding (1989)
    Springer
    Theoretical and applied genetics 77 (1989), S. 353-359 
    Details
    ISSN: 1432-2242
    Keywords: Introgression ; Linkage drag ; Lycopersicon ; Restriction fragment length polymorphisms ; Tobacco mosaic virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genes introduced into cultivated plants by backcross breeding programs are flanked by introgressed segments of DNA derived from the donor parent. This phenomenon is known as linkage drag and is frequently thought to affect traits other than the one originally targeted. The Tm-2 gene of Lycopersicon peruvianum, which confers resistance to tobacco mosaic virus, was introduced into several different tomato cultivars (L. esculentum) by repeated backcrossing. We have measured the sizes of the introgressed segments flanking the Tm-2 locus in several of these cultivars using a high density map of restriction fragment length polymorphic (RFLP) markers. The smallest introgressed segment is estimated to be 4 cM in length, while the longest is over 51 cM in length and contains the entire short arm of chromosome 9. Additionally, RFLP analysis was performed on remnant seed from different intermediate generations corresponding to two different backcross breeding programs for TMV resistance. The results reveal that plants containing desirable recombination near the resistance gene were rarely selected during backcrossing and, as a result, the backcross breeding method was largely ineffective in reducing the size of linked DNA around the resistance gene. We propose that, by monitoring recombination around genes of interest with linked RFLP markers, one can quickly and efficiently reduce the amount of linkage drag associated with introgression. Using such a procedure, it is estimated that an introgressed segment can be obtained in two generations that is as small as that which would otherwise require 100 backcross generations without RFLP selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305828
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  • 15
    Electronic Resource
    Electronic Resource
    Mapping oligogenic resistance to powdery mildew in mungbean with RFLPs (1993)
    Springer
    Theoretical and applied genetics 87 (1993), S. 243-249 
    Details
    ISSN: 1432-2242
    Keywords: Molecular markers ; Polygenic ; Quantitative trait loci (QTL)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used restriction fragment length polymorphisms (RFLPs) to map genes in mungbean (Vigna radiata) that confer partial resistance to the powdery mildew fungus, Erysiphe polygoni. DNA genotypes for 145 RFLP loci spanning 1570 centimorgans of the mungbean genome were assayed in a population of 58 F2 plants. This population was derived from a cross between a moderately powdery mildew resistant (“VC3980A”) and a susceptible (“TC1966”) mungbean parent. F3 lines derived from the F2 plants were assayed in the field for powdery mildew response and the results were compared to the RFLP genotype data, thereby identifying loci associated with powdery mildew response. A total of three genomic regions were found to have an effect on powdery mildew response, together explaining 58% of the total variation. At 65 days after planting, two genomic regions were significantly associated with powdery mildew resistance. For both loci, the allele from “VC3890A” was associated with increased resistance. At 85 days, a third genomic region was also associated with powdery mildew response. For this locus, the allele from the susceptible parent (“TC1966”) was the one associated with higher levels of powdery mildew resistance. These results indicate that putative partial resistance loci for powdery mildew in mungbean can be identified with DNA markers, even in a population of modest size analyzed at a single location in a single year.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223772
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  • 16
    Electronic Resource
    Electronic Resource
    Targeted comparative genome analysis and qualitative mapping of a major partial-resistance gene to the soybean cyst nematode (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 234-241 
    Details
    ISSN: 1432-2242
    Keywords: Key words Quantitative trait locus ; QTL ; Disease resistance ; Polygenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A major partial-resistance locus to the soybean cyst nematode (Heterodera glycines Ichinohe; SCN) was identified on linkage group `G' of soybean [Glycine max (L.) Merr.] using restriction fragment length polymorphisms (RFLPs). This locus explained 51.4% (LOD=10.35) of the total phenotypic variation in disease response in soybean Plant Introduction (PI) 209332, 52.7% (LOD=15.58) in PI 90763, 40.0% (LOD=10.50) in PI 88788, and 28.1% (LOD=6.94) in `Peking'. Initially, the region around this major resistance locus was poorly populated with DNA markers. To increase marker density in this genomic region, first random, and later targeted, comparative mapping with RFLPs from mungbean [Vigna radiata (L.) R. Wilcz.] and common bean (Phaseolus vulgaris L.) was performed, eventually leading to one RFLP marker every 2.6 centimorgans (cM). Even with this marker density, the inability to resolve SCN disease response into discrete Mendelian categories posed a major limitation to mapping. Thus, qualitative scoring of SCN disease response was carried out in an F5:6 recombinant inbred population derived from `Evans'×PI 209332 using a 30% disease index cut-off for resistance. Using the computer program JoinMap, an integrated map of the region of interest was created, placing the SCN resistance locus 4.6 cM from RFLP marker B53 and 2.8 cM from Bng30. This study demonstrates how a combination of molecular-mapping strategies, including comparative genome analysis, join mapping, and qualitative scoring of a quantitative trait, potentially provide the necessary tools for high-resolution mapping around a quantitative-trait locus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050271
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  • 17
    Electronic Resource
    Electronic Resource
    Targeted isolation of simple sequence repeat markers through the use of bacterial artificial chromosomes (1999)
    Springer
    Theoretical and applied genetics 98 (1999), S. 919-928 
    Details
    ISSN: 1432-2242
    Keywords: Key words Bacterial artificial chromosome ; Simple sequence repeats ; Microsatellites ; Soybean cyst nematode ; Genetic mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Simple sequence repeats (SSRs) are versatile DNA markers that are readily assayed and highly informative. Unfortunately, non-targeted approaches to SSR development often leave large genomic regions without SSR markers. In some cases these same genomic regions are already populated by other types of DNA markers, especially restriction fragment length polymorphisms (RFLPs), random amplified polymorphic DNAs (RAPDs), and amplified fragment length polymorphisms (AFLPs). To identify SSR markers in such regions, bacterial artificial chromosome (BAC) clones can be used as intermediaries. First, one or more BAC clones in a region of interest are identified through the use of an existing DNA marker. BAC clones uncovered in this initial step are then used to create a small insert DNA library that can be screened for the presence of SSR-containing clones. Because BAC inserts are often 100-kb pairs or more in size, most contain one or more SSRs. This strategy was applied to two regions of the soybean genome near genes that condition resistance to the soybean cyst nematode on molecular linkage groups G and A2. This targeted approach to identifying new DNA markers can readily be extended to other types of DNA markers, including single nucleotide polymorphisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051151
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  • 18
    Electronic Resource
    Electronic Resource
    A bacterial artificial chromosome library for soybean and identification of clones near a major cyst nematode resistance gene (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 196-202 
    Details
    ISSN: 1432-2242
    Keywords: Key words Chromosome walking ; Gene mapping ; Glycine max ; Heterodera glycines ; High-molecular-weight DNA ; Positional cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We constructed a bacterial artificial chromosome (BAC) library for soybean (Glycine max) consisting of approximately 30 000 clones with an average insert size of 120 kilobase pairs. The library was successfully screened with restriction fragment length polymorphism (RFLP) and microsatellite markers tightly linked to a major resistance gene for the cyst nematode, Heterodera glycines. Since many soybean RFLPs hybridize to duplicate loci, BACs homologous to duplicate RFLP loci were distinguished by digestion with the restriction enzyme originally used to map the RFLP, followed by a comparison of the hybridizing fragments. Linkage mapping of BAC clones identified with markers linked to the cyst nematode resistance gene demonstrated that these clones were located at the expected chromosomal positions and that there were no indications of chimeras within the genomic inserts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050727
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  • 19
    Electronic Resource
    Electronic Resource
    RFLP mapping of a major bruchid resistance gene in mungbean (Vigna radiata, L. Wilczek) (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 839-844 
    Details
    ISSN: 1432-2242
    Keywords: Callosobruchus ; DNA Markers ; Insect ; Legume ; Restriction fragment length polymorphisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Bruchids (genus Callosobruchus) are among the most destructive insect pests of mungbeans and other members of the genus, Vigna. Genetic resistance to bruchids was previously identified in a wild mungbean relative, TC1966. To analyze the underlying genetics, accelerate breeding, and provide a basis for map-based cloning of this gene, we have mapped the TC1966 bruchid resistance gene using restriction fragment length polymorphism (RFLP) markers. Fifty-eight F2 progeny from a cross between TC1966 and a susceptible mungbean cultivar were analyzed with 153 RFLP markers. Resistance mapped to a single locus on linkage group VIII, approximately 3.6 centimorgans from the nearest RFLP marker. Because the genome of mungbean is relatively small (estimated to be between 470 and 560 million base pairs), this RFLP marker may be suitable as a starting point for chromosome walking. Based on RFLP analysis, an individual was also identified in the F2 population that retained the bruchid resistance gene within a tightly linked double crossover. This individual will be valuable in developing resistant mungbean lines free of linkage drag.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227394
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  • 20
    Electronic Resource
    Electronic Resource
    Molecular taxonomic relationships in the genus Vigna based on RFLP analysis (1993)
    Springer
    Theoretical and applied genetics 86 (1993), S. 97-104 
    Details
    ISSN: 1432-2242
    Keywords: Vigna ; Numerical taxonomy ; RFLP ; Asiatic grams ; Cowpea ; Bambara groundnut
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The taxonomy of the genus Vigna has been primarily based on morphological attributes. We have used 27 genomic clones from soybean, common bean, mungbean and cowpea to examine restriction fragment length polymorphism (RFLP) among 44 accessions of different species belonging to four subgenera of the genus Vigna. One accession each of common bean (Phaseolus vulgaris) and soybean (Glycine max) was included in the study. Total DNA from the various genotypes was digested with one restriction enzyme (Eco RV). Results of a numerical taxonomic analysis showed a high level of genetic variation within the genus with a remarkably higher amount of variation associated with Vigna sp. from Africa relative to those from Asia. The distinctness of the Asiatic grams in subgenus Ceratotropis, cowpea in section Catiang, bambara groundnut (V. subterranean) and members of the subgenus Plectotropis was elucidated by this study. Members of the subgenus Plectotropis were closer in genome homology to those of subgenus Vigna section Catiang than to those of subgenus Ceratotropis. The relative positions of some genotypes to one another on the dendrogram and minimum spanning tree were discussed in regard to hybridisations aimed generating well-saturated genomic maps and interspecies transfer of desirable genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223813
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