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  • 1
    ISSN: 1573-5060
    Keywords: bean common mosaic virus (BCMV) ; bean common mosaic necrosis virus(BCMNV) ; epistatic resistance genes ; gene pyramiding ; Phaseolus vulgaris ; SCAR marker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pyramiding epistatic resistance genes to improve long term disease resistance has challenged plant breeders. Indirect selection using tightly linked markers will often facilitate the breeding of desired epistatic resistance gene combinations. In common bean, the most effective strategy for broad spectrum control of the bean common mosaic virus disease is to combine I, bc-u, bc-1 2, bc-2 2, and bc-3 genes. We describe the use of near-isogenic lines and bulked segregant analysis to identify a marker tightly linked with the bc-1 2 gene. The recessive bc-1 2 gene conditions resistance to specific strains of bean common mosaic virus and bean common mosaic necrosis virus and is masked by the bc-2 2 and bc-3 genes. We identified a RAPD marker completely linked (0 recombinants) with bc-1 2, based on 72 F3 progeny generated from a cross between the contrasting near isogenic lines (I + bc-1/I + bc-1 2). Segregation in this I gene background revealed that bc-1 2 was dominant to bc-1 in conferring resistance to top necrosis in the allelic series Bc-1 〉 bc-1 2 〉 bc-1. To facilitate marker-assisted selection of bc-1 2 across breeding programs, the RAPD was converted to a SCAR marker, designated SBD51300. Tight linkage (0 recombinants) was confirmed in a second population of 58 F2 progeny co-segregating for SBD51300 and bc-1 2 gene from a different source. Based on a survey of 130 genotypes, the SCAR will be useful for MAS of bc-1 2 in most beans of Middle American origin and snap beans, but will have very limited utility in the case of kidney and cranberry beans. The SBD51300 marker mapped on linkage group B3, revealing independence of bc-1 2 from the I gene on B2 and bc-3 gene on B6, which supports the opportunity to readily combine genes for broad spectrum and pyramided resistance to bean common mosaic potyviruses in a single bean cultivar.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Molecular breeding 4 (1998), S. 1-11 
    ISSN: 1572-9788
    Keywords: Phaseolus vulgaris ; epistasis ; marker-assisted selection ; indirect selection ; linkage ; pathogens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Diseases are regarded as the leading constraint to increased common bean (Phaseolus vulgaris L.) production worldwide. The range in variability and complexity among bean pathogens can be controlled with different single gene and quantitative resistance sources. Combining these resistance sources into commercial cultivars is a major challenge for bean breeders. To assist breeders, a major effort to identify RAPD markers tightly linked to different genes was undertaken. To date, 23 RAPD and five SCAR markers linked to 15 different resistance genes have been identified, in addition to QTL conditioning resistance to seven major pathogens of common bean. We review the feasibility of using marker-assisted selection (MAS) to incorporate disease resistance into common bean. Indirect selection of single resistance genes in the absence of the pathogen and the opportunity afforded breeders to pyramid these genes to improve their longevity and retain valuable hypostatic genes is discussed. The role of markers linked to the QTL controlling complex resistance and the potential to combine resistance sources using marker based selection is reviewed. Improving levels of selection efficiency using flanking markers, repulsion-phase linkages, co-dominant marker pairs, recombination-facilitated MAS and SCAR markers is demonstrated. Marker-assisted selection for disease resistance in common bean provides opportunities to breeders that were not feasible with traditional breeding methods.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Sclerotinia sclerotiorum (Lib.) de Bary, causal organism of white mold disease in common bean (Phaseolus vulgris L.), have been found and exploited by breeders. Our objective was to screen a subsample of the core collection of P. vulgris accessions representing the active USDA National Plant Germplasm System collection of 1698 accessions from Central and South America for reaction to white mold using a greenhouse straw test. White mold reactions were rated for 89 accessions from 1 = no disease symptoms to 9 = total plant collapse. Eleven core accessions, PIs (plant introductions) 152311, 207136, 207154, 290990, 290995, 293353, 313850, 415886, 415906, 415913, and 415936, with scores 〈 5 were identified as having putative physiological resistance to white mold. An expanded screening among 35 accessions from the active collection which had similar passport data to the resistant core PIs 207136, 290990, and 313850 revealed 20 resistant accessions with disease scores 〈 5. A similar expanded screening of 18 accessions with similar passport data to core PIs 310674, 313608, and 415954 that had scores 〉 6, revealed only four accessions with scores 〈 5. These results indicated that a subsample of the core collection was useful for identifying ranges of accessions within the active Phaseolus collection that possessed a high incidence of putative physiological resistance to white mold.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Macrophomina phaseolina (Tassi) Goid.] can be a serious disease of common bean (Phaseolus vulgarisL.) under drought and high temperature conditions in some regions. The mode of inheritance of valuable sources of resistance is lacking. We studies inheritance of field resistance to ashy stem blight in a recombinant inbred population ('Dorado' X XAN 176) consisting of 119 F5∝7 recombinant inbred lines (RILs) tested in replicated experiments across 2 yr. A score from 1 to 9 (no disease to severe disease) was used to measure disease reaction. Moderate HNS (0.53 and 0.57) and near-normal frequency distribution of RILs for mean disease score each year indicated a lack of discrete segregation classes. The phenotypic variation across a subgroup composed of 79 RILs was further investigated with 165 randomly amplified polymorphic DNA (RAPD) markers by one-way analyses of variance and interval mapping. Five quantitative trait loci (QTL), explaining 19, 15, 15, 13, and 13% of the phenotypic variation for disease score, were detected in 1993. Three of these QTL , explaining 15, 12, and 12% of the variation in disease reaction, were detected in 1994. Multiple QTL regression models (P 〈 0.01) explained up to 47% (four loci) of the phenotypic variation for disease score in 1993 and 28% (three loci) in 1994. The five QTL, all derived from XAN 176, generally showed additive effects. These QTL-linked RAPD markers may prove useful for indirect selection of field resistance to ashy stem blight derived from XAN 176.
    Type of Medium: Electronic Resource
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