The Andean common bean AND 277 has the Co-14 and the Phg-1 alleles that confer resistance to 21 and eight races, respectively, of the anthracnose (ANT) and angular leaf spot (ALS) pathogens. Because of its broad resistance spectrum, Co-14 is one of the main genes used in ANT resistance breeding. Additionally, Phg-1 is used for resistance to ALS. In this study, we elucidate the inheritance of the resistance of AND 277 to both pathogens using F2 populations from the AND 277 × Rudá and AND 277 × Ouro Negro crosses and F2:3 families from the AND 277 × Ouro Negro cross. Rudá and Ouro Negro are susceptible to all of the above races of both pathogens. Co-segregation analysis revealed that a single dominant gene in AND 277 confers resistance to races 65, 73, and 2047 of the ANT and to race 63-23 of the ALS pathogens. Co-14 and Phg-1 are tightly linked (0.0 cM) on linkage group Pv01. Through synteny mapping between common bean and soybean we also identified two new molecular markers, CV542014450 and TGA1.1570, tagging the Co-14 and Phg-1 loci. These markers are linked at 0.7 and 1.3 cM, respectively, from the Co-14/Phg-1 locus in coupling phase. The analysis of allele segregation in the BAT 93/Jalo EEP558 and California Dark Red Kidney/Yolano recombinant populations revealed that CV542014450 and TGA1.1570 segregated in the expected 1:1 ratio. Due to the physical linkage in cis configuration, Co-14 and Phg-1 are inherited together and can be monitored indirectly with the CV542014450 and TGA1.1570 markers. These results illustrate the rapid discovery of new markers through synteny mapping. These markers will reduce the time and costs associated with the pyramiding of these two disease resistance genes.

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 F2 population from the Rudá × Ouro Negro cross and the F2:3 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 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.

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.

Anthracnose, caused by Colletotrichum lindemuthianum, is a major disease of dry bean and results great yield losses. The objective of this work was to characterize the anthracnose resistance gene present in the Andean cultivar ÔPitangaÕ. This cultivar was crossed with the cultivars Michelite, Michigan Dark Red Kidney, Cornell 49-242, Mexico 222, PI 207262, TU, AB 136, G 2333, BAT 93, SEL 1308, H1 line, Ouro Negro, Jalo Vermelho and Jalo Listras Pretas to obtain F 1 and F 2 populations. These populations were then inoculated with races 23, 64, 65, 73 and 2047 of C. lindemuthianum. The segregation ratio was 3 resistant : 1 susceptible, which shows that resistance inheritance is controlled by a single dominant gene. The results from allelism tests in fourteen F 2 populations fit a 15 resistant : 1 susceptible ratio, which indicates that the resistance present in the ÔPitangaÕ cultivar is dominant and independent from genes and alleles already characterized: Co-1, Co-2, Co-3, Co-4 2 , Co-5, Co-6, Co-7, Co-9, Co-10, Co-11, Co-12 and Co-13. The authors suggest the symbol Co-14 to represent the gene present in the ÔPitangaÕ cultivar.

The common bean cultivar Crioulo 159 provides a valuable source of resistance to Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi & Cavara. The objective of this study was to characterize the genetic resistance of Crioulo 159 to C. lindemuthianum races 2, 64, 73, and 2047 through inheritance, allelism testing, and molecular analysis. Populations were obtained from crosses between Crioulo 159 and cultivars possessing anthracnose resistance genes. Inheritance tests performed in the F2 population and F2:3 families derived from Crioulo 159 (R, resistant) × Cornell 49–242 (S, susceptible) and inoculated with races 2047 and 73 showed segregation that fit ratios of 3R:1S and 1RR:2RS:1SS, respectively, indicating the action of a dominant resistance gene in Crioulo 159. The absence of recombination between two identical sets of F2:3 families inoculated with C. lindemuthianum race 2047 and 73, respectively, allowed the conclusion that a single dominant gene controls the resistance of Crioulo 159 to both races. Allelism tests revealed the independence of the gene in Crioulo 159 from those previously characterized for anthracnose resistance genes. Based on the results, we propose naming this newly discovered anthracnose resistance gene in Crioulo 159 as Co‐16. Molecular analyses revealed that sequence‐tagged site marker g2467900/800 is linked in coupling phase at 4.8 cM from the Co‐16 locus on chromosome Pv04. Additionally, molecular markers g2303, BARCPVSSR04561 and BARCPVSSR04570, which are linked to the Co‐34 allele in Ouro Negro, were not linked to the Co‐16 gene in Crioulo 159.

Key message A common bean shattering-resistance allele of PvPdh1 reduces pod twists during dehiscence, shows dominance that varies by phenotyping method, is part of a selective sweep, and can be introgressed using CAPS markers. Abstract Some varieties of common bean (Phaseolus vulgaris L.) sufer from pod shattering, which can severely reduce yields, especially in arid conditions. The PvPdh1 locus on chromosome Pv03 has recently been described as a major locus controlling pod shattering in common bean and could be used to mitigate pod shattering in the future. Despite this, the role of a possible second locus on chromosome Pv08 remains unclear and patterns of dominance and epistasis between alleles of these genes have not been resolved. This information will be vital for eicient selection to decrease pod shattering. Further, the genetic diversity around the PvPdh1 gene has not yet been thoroughly explored, and there are not yet genetic screens that can be used to evaluate pod shattering in segregating populations. Here, we have developed a recombinant inbred population to determine the roles of genes implicated in pod shattering and evaluate the patterns of dominance among the relevant alleles. Our results suggest that a PvPdh1 allele reduces pod valve twisting, and its dominance varies by phenotyping method. This allele is the only genetic variant that provides environmentally stable and widespread resistance to pod shattering in Middle American common beans grown for grain. Further analyses identiied a selective sweep around PvPdh1 with greater nucleotide diversity in individuals with the ancestral, shattering-susceptible allele. Finally, we developed simple, efective CAPS markers to facilitate the introgression of PvPdh1 into new varieties of common bean. These genetic resources will be critical for improving the aridity resilience of a major global staple.

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The aim of this study was to investigate the changes in photosynthetic pigments and carbohydrate contents on resistant and susceptible plants of Phaseolus vulgaris L. (cvs. Mexico 222 and Widusa) infected by Colletotrichum lindemuthianum race 23. The experimental design used was entirely randomized in factorial scheme, with 2 cultivars (Mexico 222 and Widusa) and 2 treatments (control and inoculated). The cultivar Widusa (susceptible) showed a significant reduction in photosynthetic pigments, and an increase in the total carbohydrates, sucrose and reducing carbohydrates, whereas the cultivar Mexico 222 (resistant) showed a significant change in the carotenoid and total carbohydrate contents.