Article

Marker-assisted dissection of oligogenic anthracnose resistance in the common bean cultivar, ‘G2333’. Theor Appl Genet

Federal University of Santa Catarina, Nossa Senhora do Destêrro, Santa Catarina, Brazil
Theoretical and Applied Genetics (Impact Factor: 3.79). 12/1997; 96(1):87-94. DOI: 10.1007/s001220050713

ABSTRACT

 Two independently assorting dominant genes conditioning resistance to bean anthracnose were identified in an F2 population derived from the highly resistant bean differential cultivar, ‘G 2333’. One gene was allelic to the Co-4 gene in the differential cultivar ‘TO’ and was named Co-4

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, whereas the second gene was assigned the temporary name Co-7 until a complete characterization with other known resistance genes can be conducted. Two RAPD markers linked to the Co-4

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allele were identified. One RAPD, OAS13950, co-segregated with no recombinants in two segregating populations of 143 F2 individuals, whereas the second RAPD, OAL9740, mapped at 3.9 cM from the Co-4

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allele. Two 24-mer SCAR primers (SAS13), developed from the OAS13950 RAPD marker, were dominant and polymorphic, similar to the original RAPD, and supported the tight linkage between the marker(s)
and the Co-4

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allele. The markers were present in germplasm with known resistance alleles at the Co-4 locus. The presence of the markers in two other differential cultivars not previously characterized and in four navy bean
cultivars suggests the existence of a gene family for anthracnose resistance at or near the Co-4 locus. Since the Co-7 gene was present only in germplasm which also possessed the Co-4

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and Co-5 genes, the SAS13 markers were used in combination with standard inoculation techniques to identify F3 lines in which the Co-7 gene was homozygous and the Co-4

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allele was absent. A similar strategy of marker-assisted dissection is proposed to identify resistant lines in which the
Co-5 gene is absent and the Co-7 gene is present by selecting against the OAB3450 marker, which has been shown previously to be linked to the Co-5 gene. These genes cannot be distinguished using traditional screening methods since all current races of the pathogen virulent
to the Co-5 gene are avirulent to the Co-4

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and Co-7 genes. We describe the use of molecular markers tightly linked to resistance genes to facilitate the identification of an
uncharacterized resistance gene for which no discriminating race of the pathogen is known.

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Available from: Maeli Melotto, Oct 27, 2015
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    • "Additionally, its significance has been highlighted due to its ample spectra of genetic resistance (Young et al., 1998). Therefore, it was verified that the gene present in Corinthiano is independent from the previously characterized genes: Co-1, Co-1 4 /Phg-1, Co-2, Co-3, Co-3 3 , Co-3 4 /Phg-3, Co-4, Co-4 2 , Co-5, Co-5 2 , Co-6, Co-3 5 , Co-11, Co-12, Co-13, Co-14, and Co-16 that are present in the tested cultivars. "
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    ABSTRACT: The objectives of this study were to characterize the genetic resistance in the Andean common bean (Phaseolus vulgaris L.) cultivar Corinthiano to races 8, 65, 89, and 2047 of Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi & Cavara through inheritance and allelism tests and to map the source of resistance. Corinthiano was crossed with cultivars Michelite, Michigan Dark Red Kidney (MDRK), Cornell 49-242, Mexico 222, PI 207262, TO, TU, AB 136, G 2333, Jalo Listras Pretas (JLP), Jalo Vermelho (JV), BAT 93, Ouro Negro, AND 277, Pitanga, SEL 1308, H1 line, and Crioulo 159 to generate F2 populations. Inheritance tests conducted in F2 population and F2:3 families from the cross Corinthiano (resistant [R]) × Cornell 49-242 (susceptible [S]) inoculated with race 2047 showed segregation that fit ratios of 3R:1S and 1RR:2Rr:1rr, respectively, indicating the action of a dominant resistance gene in Corinthiano. Allelism tests demonstrated that the gene in Corinthiano is independent from those previously characterized genes: Co-1, Co-14, Co-2, Co-3, Co-33, Co-34, Co-35, Co-4, Co-5, Co-52, Co-42, Co-6, Co-11, Co-12, Co-13, Co-14, and Co-16 that are present in the genotypes tested. The symbol Co-15 was assigned to this newly discovered anthracnose resistance gene in Corinthiano. Molecular analyses revealed that the sequence-tagged site (STS) marker g2685 is linked in coupling phase at 5.6 cM from the Co-15 locus. This marker was also polymorphic in the mapping population BAT 93/Jalo EEP 558, which confirmed the location of this marker and the Co-15 gene on Pv04. Corinthiano has shown to be an important source of resistance to anthracnose, possessing a new gene that should be valuable in breeding for anthracnose resistance in common bean.
    Full-text · Article · Sep 2015 · Crop Science
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    • "The Co-7 resistance allele was first described in the differential cultivar G 2333 (Young et al., 1998) and was the third independent anthracnose resistance gene to be identified in this cultivar. The Co-7 gene was distinguished from other anthracnose resistance genes through analyses carried out by Young et al. (1998), in which several tests involving markerassisted selection and inoculation with different races of C. lindemuthianum were applied. "

    Full-text · Article · Jan 2012
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    • "(c) Mapping of the Rpsar-2 gene to the end of LG B8. SAS13 and Dj1kSCAR are two SCAR markers linked to the anthracnose Co-4 R gene (Adam-Blondon, 1994; Young et al., 1998). Oval symbols correspond to R genes. "
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    ABSTRACT: *In plants, the evolution of specific resistance is poorly understood. Pseudomonas syringae effectors AvrB and AvrRpm1 are recognized by phylogenetically distinct resistance (R) proteins in Arabidopsis thaliana (Brassicaceae) and soybean (Glycine max, Fabaceae). In soybean, these resistances are encoded by two tightly linked R genes, Rpg1-b and Rpg1-r. To study the evolution of these specific resistances, we investigated AvrB- and AvrRpm1-induced responses in common bean (Phaseolus vulgaris, Fabaceae). *Common bean genotypes of various geographical origins were inoculated with P. syringae strains expressing AvrB or AvrRpm1. A common bean recombinant inbred line (RIL) population was used to map R genes to AvrRpm1. *No common bean genotypes recognized AvrB. By contrast, multiple genotypes responded to AvrRpm1, and two independent R genes conferring AvrRpm1-specific resistance were mapped to the ends of linkage group B11 (Rpsar-1, for resistance to Pseudomonas syringae effector AvrRpm1 number 1) and B8 (Rpsar-2). Rpsar-1 is located in a region syntenic with the soybean Rpg1 cluster. However, mapping of specific Rpg1 homologous genes suggests that AvrRpm1 recognition evolved independently in common bean and soybean. *The conservation of the genomic position of AvrRpm1-specific genes between soybean and common bean suggests a model whereby specific clusters of R genes are predisposed to evolve recognition of the same effector molecules.
    Full-text · Article · Sep 2010 · New Phytologist
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