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Anthracnose (ANT) and angular leaf spot (ALS) caused by Colletotrichum lindemuthianum and Pseudocercospora griseola, respectively, are devastating diseases of common bean around the world. Therefore, breeders are constantly searching for new genes with broad-spectrum resistance against ANT and ALS. This study aimed to characterize the genetic resistance of California Dark Red Kidney (CDRK) to C. lindemuthianum races 73, 2047, and 3481 and P. griseola race 63–39 through inheritance, allelism testing, and molecular analyses. Genetic analysis of response to ANT and ALS in recombinant inbred lines (RILs) from a CDRK × Yolano cross (CY) showed that the resistance of CDRK cultivar is conferred by a single dominant loci, which we named CoPv01CDRK/PhgPv01CDRK. Allelism tests performed with race 3481showed that the resistance gene in CDRK is independent of the Co-1 and Co-AC. We conducted co-segregation analysis in genotypes of 110 CY RILs and phenotypes of the RILs in response to different races of the ANT and ALS pathogens. The results revealed that CoPv01CDRK and PhgPv01CDRK are coinherited, conferring resistance to all races. Genetic mapping of the CY population placed the CoPv01CDRK/PhgPv01CDRK loci in a 245 Kb genomic region at the end of Pv01. By genotyping 19 RILs from the CY population using three additional markers, we fine-mapped the CoPv01CDRK/PhgPv01CDRK loci to a smaller genomic region of 33 Kb. This 33 Kb region harbors five predicted genes based on the common bean reference genome. These results can be applied in breeding programs to develop bean cultivars with ANT and ALS resistance using marker-assisted selection. [ABSTRACT FROM AUTHOR]

Anthracnose (ANT) and angular leaf spot (ALS) are devastating diseases of common bean ( Phaseolus vulgaris L.). Ouro Negro is a highly productive common bean cultivar, which contains the Co- 10 and Phg- ON genes for resistance to ANT and ALS, respectively. In this study, we performed a genetic co-segregation analysis of resistance to ANT and ALS using an F population from the Rudá × Ouro Negro cross and the F families from the AND 277 × Ouro Negro cross. Ouro Negro is resistant to races 7 and 73 of the ANT and race 63-39 of the ALS pathogens. Conversely, cultivars AND 277 and Rudá are susceptible to races 7 and 73 of ANT, respectively. Both cultivars are susceptible to race 63-39 of ALS. Co-segregation analysis revealed that Co- 10 and Phg- ON were inherited together, conferring resistance to races 7 and 73 of ANT and race 63-39 of ALS. The Co- 10 and Phg- ON genes were co-segregated and were tightly linked at a distance of 0.0 cM on chromosome Pv04. The molecular marker g2303 was linked to Co- 10 and Phg- ON at a distance of 0.0 cM. Because of their physical linkage in a cis configuration, the Co- 10 and Phg- ON resistance alleles are inherited together and can be monitored with great efficiency using g2303. The close linkage between the Co- 10 and Phg- ON genes and prior evidence are consistent with the existence of a resistance gene cluster at one end of chromosome Pv04, which also contains the Co- 3 locus and ANT resistance quantitative trait loci. These results will be very useful for breeding programs aimed at developing bean cultivars with ANT and ALS resistance using marker-assisted selection. [ABSTRACT FROM AUTHOR]

Novel sources of resistance are continuously needed to combat anthracnose disease in common bean (Phaseolus vulgaris L.) caused by the hypervariable pathogen Colletotrichum lin- demuthianum (Sacc. and Magnus) Briosi and Cavara. We sought to characterize the novel anthracnose resistance in Andean common bean landrace 'Jab Listras Pretas' (JLP). Jab Listras Pretas is resistant to races 9, 64, 65, and 73 of the anthracnose pathogen used in this study. To examine inheritance of anthracnose resistance in JLP, F2 populations JLP/Mexico 222 and JLP/Cornell 49242 were inoculated with discriminating races of the pathogen. Segregation for resistance in both F2 populations fit a 3:1 resistant/susceptible ratio suggesting that the anthracnose resistance in JLP is controlled by a single dominant gene. To establish independence of the resistance gene in JLP from other published resistance genes, allelism tests were conducted with 14 F2 populations derived from crossing JLP with Andean cultivars carrying anthracnose resistance genes Co-1, Co-12, Co-13, Co-15, and Co-12, and with Middle American cultivars with Co-2, Co-3, Co-43, Co-5, Co-6, Co-7, Co-9, Co-l0, and Co-1l. Results revealed the resistance gene in JLP was independent of the Andean loci Co-1 and Co-12, and the nine Middle American anthracnose resistance genes. The symbol Co-13 was assigned to this newly discovered anthracnose resistance gene in Brazilian Andean common bean landrace JLP. [ABSTRACT FROM AUTHOR]

‘Jalo Vermelho’ is a large seeded Andean landrace of common bean ( Phaseolus vulgaris L.) that constitutes an important source of anthracnose resistance, disease caused by Colletotrichum lindemuthianum. This landrace has different resistance spectrum, when compared with cultivars of Andean origin, indicating the presence of an anthracnose-resistant gene different from Co- 1 locus. This anthracnose resistance was characterized by inheritance and allelism tests were carried out on the following genes: Co- 1, Co- 1 2, Co- 1 3, Co- 1 5, Co- 2, Co- 3, Co- 4, Co- 5, Co- 6, Co- 7, Co- 9, Co- 10, Co- 11 and Co-13. Resistance to races 23, 55, 89 and 453 in ‘Jalo Vermelho’ was conditioned by a single dominant gene. Allelism tests in F2 populations demonstrated that ‘Jalo Vermelho’ carries a dominant gene located at a distinct locus, differing from previously characterized genes. Based on its independence from previously described loci, the authors propose that the ‘Jalo Vermelho’s gene should be named Co- 12. This new gene is a valuable source of resistance to anthracnose which can be transferred to commercial cultivars to enhance the effectiveness of resistance gene pyramiding in bean breeding programmes. [ABSTRACT FROM AUTHOR]

Pathogenicity of physiologically distinct races of Colletotrichum lindemuthianum originating from Andean (races 7, 19 and 55) and Mesoamerican (races 9, 31, 65, 69, 73, 81, 89, 95 and 453) locations of the new world were evaluated on 26 landrace genotypes of common bean ( Phaseolus vulgaris L.) from Paraná State, Brazil. Races 7 (Andean), 65, 73 and 89 (Mesoamerican) were the most pathogenic, while race 31 (Mesoamerican) was the least pathogenic. Most of the landrace genotypes evaluated (88%) were resistant to race 31, except Carioca 3, Preto 1 and Preto 2. In addition, about 50% of the landrace genotypes had resistance to races 9, 19, 55 and 453; and about 30% to races 7, 65, 69, 73, 81, 89 and 95. The resistance index, which measured the pathogenicity response averaged across all the physiologically distinct Andean and Mesoamerican races of C. lindemuthianum, of the landrace genotypes ranged from 8% to 83%. The most resistant cultivars were Carioca Pintado 1, Carioca Pintado 2, Jalo Vermelho and Jalo de Listras Pretas. In contrast, the most susceptible cultivars were Jalo Pardo, Jalo Pintado 1 and Bolinha that showed resistance only to the least pathogenic race 31. These results indicated that many of the common bean landrace cultivars evaluated have genes that could be useful in breeding programmes to enhance resistance to Andean and Mesoamerican races of C. lindemuthianum. [ABSTRACT FROM AUTHOR]

Snap bean ( Phaseolus vulgaris L.) cultivar, Widusa, was crossed to Michigan Dark Red Kidney (MDRK), Michelite, BAT 93, Mexico 222, Cornell 49–242, and TO cultivars to study the inheritance of resistance to anthracnose in Widusa. The segregation patterns observed in six F2 populations supported an expected 3R:1S ratio suggesting that Widusa carries a single dominant gene conditioning resistance to races 7, 65, 73, and 453 of Colletotrichum lindemuthianum, the causal organism of bean anthracnose. Allelism tests conducted with F2 populations derived from crosses between Widusa and Cornell 49–242 ( Co-2), Mexico 222 ( Co-3), TO ( Co-4), TU ( Co-5), AB 136 ( Co-6), BAT 93 ( Co-9), and Ouro Negro ( Co-10), inoculated with races 7, 9, 65 and 73, showed a segregation ratio of 15R:1S. These results suggest that the anthracnose resistance gene in Widusa is independent from the Co-2, Co-3, Co-4, Co-5, Co-6, Co-9, and Co-10 genes. A lack of segregation was observed among 200 F2 individuals from the cross Widusa/MDRK, and among 138 F2 individuals from the cross Widusa/Kaboon inoculated with race 65, suggesting that Widusa carries an allele at the Co-1 locus. We propose that the anthracnose resistance allele in Widusa be named Co-1 5 as Widusa exhibits a unique reaction to race 89 compared to other alleles at the Co-1 locus. RAPD marker A181500 co-segregated in repulsion-phase linkage with the Co-1 5 gene at a distance of 1.2 cM and will provide bean breeders with a ready tool to enhance the use of the Co-1 5 gene in future bean cultivars. [ABSTRACT FROM AUTHOR]