Genetic dissection of the resistance to nine anthracnose races in the common bean differential cultivars MDRK and TU

Resistance to nine races of the pathogenic fungus Colletotrichum lindemuthianum, causal agent of anthracnose, was evaluated in F3 families derived from the cross between the anthracnose differential bean cultivars TU (resistant to races, 3, 6, 7, 31, 38, 39, 102, and 449) and MDRK (resistant to races, 449, and 1545). Molecular marker analyses were carried out in the F2 individuals in order to map and characterize the anthracnose resistance genes or gene clusters present in these two differential cultivars. The results of the combined segregation indicate that at least three independent loci conferring resistance to anthracnose are present in TU. One of them, corresponding to the previously described anthracnose resistance locus Co-5, is located in linkage group B7, and is formed by a cluster of different genes conferring specific resistance to races, 3, 6, 7, 31, 38, 39, 102, and 449. Evidence of intracluster recombination between these specific resistance genes was found. The second locus present in TU confers specific resistance to races 31 and 102, and the third locus confers specific resistance to race 102, the location of these two loci remains unknown. The resistance to race 1545 present in MDRK is due to two independent dominant genes. The results of the combined segregation of two F4 families showing monogenic segregation for resistance to race 1545 indicates that one of these two genes is linked to marker OF10530, located in linkage group B1, and corresponds to the previously described anthracnose resistance locus Co-1. The second gene conferring resistance to race 1545 in MDRK is linked to marker Pv-ctt001, located in linkage group B4, and corresponds to the Co-3/Co-9 cluster. The resistance to race 449 present in MDRK is conferred by a single gene, located in linkage group B4, probably included in the same Co-3/Co-9 cluste

Genetic mapping of the Andean anthracnose resistance gene present in the common bean cultivar BRSMG Realce.

The rajado seeded Andean bean (Phaseolus vulgaris L.) cultivar BRSMG Realce (striped seed coat) developed by Embrapa expressed a high level of anthracnose resistance, caused by Colletotrichum lindemuthianum, in field and greenhouse screenings. The main goal of this study was to evaluate the inheritance of anthracnose resistance in BRSMG Realce, map the resistance locus or major gene cluster previously named as Co-Realce, identify resistance-related positional genes, and analyze potential markers linked to the resistance allele. F2 plants derived from the cross BRSMG Realce × BRS FC104 (Mesoamerican) and from the cross BRSMG Realce × BRS Notável (Mesoamerican) were inoculated with the C. lindemuthianum races 475 and 81, respectively. The BRSMG Realce × BRS FC104 F2 population was also genotyped using the DArTseq technology. Crosses between BRSMG Realce and BAT 93 (Mesoamerican) were also conducted and resulting F2 plants were inoculated with the C. lindemuthianum races 65 and 1609, individually. The results shown that anthracnose resistance in BRSMG Realce is controlled by a single locus with complete dominance. A genetic map including 1,118 SNP markers was built and shown 78% of the markers mapped at a distances less than 5.0 cM, with a total genetic length of 4,473.4 cM. A major locus (Co-Realce) explaining 54.6% of the phenotypic variation of symptoms caused by the race 475 was identified in Pv04, flanked by the markers snp1327 and snp12782 and 4.48 cM apart each other. These SNPs are useful for marker-assisted selection, due to an estimated selection efficiency of 99.2%. The identified resistance allele segregates independently of the resistance allele Co-33 (Pv04) present in BAT 93. The mapped genomic region with 704,867 bp comprising 63 putative genes, 44 of which were related to the pathogen-host interaction. Based on all these results and evidence, anthracnose resistance in BRSMG Realce should be considered as monogenic, useful for breeding purpose. It is proposed that locus Co-Realce is unique and be provisionally designated as CoPv04R until be officially nominated in accordance with the rules established by the Bean Improvement Cooperative Genetics Committee

Fine mapping of anthracnose resistance allele Co-14 in the common bean cultivar and 277.

The objectives of this study were to fine-map the anthracnose-resistance locus in AND 277 and to identify DNA markers tightly linked to the Co-14 allele, previously mapped on Pv01

Mapping of an andean gene for anthracnose resistance (Co-13) in common bean (Phaseolus vulgaris L.) Jalo Listras Pretas landrace

Abstract The common bean (Phaseolus vulgaris L.) andean Jalo Listras Pretas (JLP) landrace is an important source of resistance to anthracnose, which is a widespread disease caused by Colletotrichum lindemuthianum fungus. This common bean landrace carries Co-13 gene, one of the nine ones identified andean anthracnose resistance genes. The present study set out to identify molecular markers associated with Co-13 by evaluating the segregation patterns of 65 molecular markers, in a F 2 population derived from a cross between JLP (resistant to race 73 of C. lindemuthianum) and Cornell 49-242 (susceptible to race 73 of C. lindemuthianum) cultivars. Bulked segregant analysis was performed to identify which of these molecular markers was linked to Co-13 in JLP. Among the analyzed molecular markers, OV20 680 marker displayed a heteromorphic band of 680 bp linked to Co-13 resistant gene in coupling phase. Genotyping of the OV20 680 marker in F 2 population revealed a recombination of 1.7%, indicating a tight linkage between the OV20 680 marker and disease resistance gene (Co-13). In the recombinant inbred population BAT93/Jalo EEP558, OV20 680 segregated according to a 1:1 ratio and mapped on linkage group Pv03 at a distance of 1.8 cM from the Co-13 locus. Jalo Listras Pretas 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. Identifying molecular markers linked to andean resistance genes may facilitate the development of cultivars with broad-based resistance to anthracnose by streamlining the process of combining andean and mesoamerican resistance genes

Selection of resistance sources to common bean anthracnose by field phenotyping and DNA marker-assisted screening.

The main goal of this work was to select resistance sources to common bean anthracnose by field phenotyping and DNA marker-assisted screening. Fifty-five common bean genotypes, including differential varieties, characterized resistance sources, elite lines, cultivars and controls, were evaluated in a field inoculation trial and screened with SCAR markers linked to resistance genes that are important in Brazil. The field trial was carried out in Santo Antônio de Goiás, GO, Brazil, during the fall/winter growing season of 2014, using artificial inoculation with a mixture of six races of Colletotrichum lindemuthianum, selected based on their high virulence and prevalence in Brazil. Amplification reactions with the SCAR markers previously identified as linked to important anthracnose resistance genes on Brazil followed standard procedures. Twenty-eight of the 58 genotypes were resistant to anthracnose (mean severity score ≤ 3.5). Ten of these 28 resistant genotypes stood out because they presented a mean anthracnose severity score of 1.0. Four of the six SCAR markers tested shown to be useful for the assisted selection of their respective target genes (SH18 and SAS13 for Co-42, SAB03 for Co-5, and SAZ20 for Co-6). Two carioca seeded elite lines were highlighted by the phenotypic and molecular screening: K10 (Co-34, Co-42, Co-5 and Co-6) and K13 (Co-4²). The phenotypic and molecular characterization of candidate resistance sources to common bean anthracnose based on their disease reaction in field inoculation trials and on the analysis with molecular markers linked to resistance genes has shown to be a useful strategy. These results aid in the selection of donor parents and resistant lines to be preferably explored by common bean breeding programs in Brazil

Identification of Clusters that Condition Resistance to Anthracnose in the Common Bean Differential Cultivars AB136 and MDRK.

The correct identification of the anthracnose resistance systems present in the common bean cultivars AB136 and MDRK is important because both are included in the set of 12 differential cultivars proposed for use in classifying the races of the anthracnose causal agent, Colletrotrichum lindemuthianum. In this work, the responses against seven C. lindemuthianum races were analyzed in a recombinant inbred line population derived from the cross AB136 × MDRK. A genetic linkage map of 100 molecular markers distributed across the 11 bean chromosomes was developed in this population to locate the gene or genes conferring resistance against each race, based on linkage analyses and χ2tests of independence. The identified anthracnose resistance genes were organized in clusters. Two clusters were found in AB136: one located on linkage group Pv07, which corresponds to the anthracnose resistance cluster Co-5, and the other located at the end of linkage group Pv11, which corresponds to the Co-2 cluster. The presence of resistance genes at the Co-5 cluster in AB136 was validated through an allelism test conducted in the F2population TU × AB136. The presence of resistance genes at the Co-2 cluster in AB136 was validated through genetic dissection using the F2:3population ABM3 × MDRK, in which it was directly mapped to a genomic position between 46.01 and 47.77 Mb of chromosome Pv11. In MDRK, two independent clusters were identified: one located on linkage group Pv01, corresponding to the Co-1 cluster, and the second located on LG Pv04, corresponding to the Co-3 cluster. This report enhances the understanding of the race-specific Phaseolus vulgaris–C. lindemuthianum interactions and will be useful in breeding programs

Molecular markers and allelic relationships of anthracnose resistance gene cluster B4 in common bean

Allelism tests and molecular marker analyses were combined to characterize the genes that, proceeding from the germplasm lines ‘A493’ and ‘A321’, confer resistance to bean anthracnose in the new breeding lines ‘A1220’ and ‘A1231’, respectively, developed through backcross breeding, using the dry bean landrace ‘Andecha’ as the recurrent parent. Allelism tests indicate that resistance to race 38 of anthracnose in genotypes ‘A1220’, ‘A1231’, and ‘BAT 93’ and in the differential cultivars ‘PI 207262’ and ‘Mexico 222’ is determined by different dominant alleles at the same locus. Therefore, the results obtained suggest that the so far considered as different genes Co-3 (described as present in ‘Mexico 222’) and Co-9 (described as present in ‘BAT 93’) are alleles of the same gene. RAPD markers OB12350, OAH181100, and OY171100 and SCAR markers SI19 and SW12 were found to be linked to the resistance gene. Data indicate that the resistance genes to race 38 present in these materials are alleles of the same R gene cluster located in linkage group B4, because markers OY171100, SI19 and SW12 were previously linked to this cluster. The SCAR markers SB12 and SAH18 were developed from RAPDs OB12350 and OAH181100, respectively, and a genetic map including the resistance gene and markers SB12, OY171100, SAH18, SW12 and SI19 was made using a F2 segregating population of 72 individuals derived from the cross ‘Andecha’ × ‘A493’

A genetic linkage map of Phaseolus vulgaris L. and localization of genes for specific resistance to six races of anthracnose (Colletotrichum lindemuthianum).

A genetic map of common bean was constructed using 197 markers including 152 RAPDs, 32 RFLPs, 12 SCARs, and 1 morphological marker. The map was established by using a F2 population of 85 individuals from the cross between a line derived from the Spanish landrace Andecha (Andean origin) and the Mesoamerican genotype A252. The resulting map covers about 1,401.9 cM, with an average marker distance of 7.1 cM and includes molecular markers linked to disease resistance genes for anthracnose, bean common mosaic virus, bean golden yellow mosaic virus, common bacterial blight, and rust. Resistance to races 6, 31, 38, 39, 65, and 357 of the pathogenic fungus Colletotrichum lindemuthianum (anthracnose) was evaluated in F3 families derived from the corresponding F2 individuals. The intermediate resistance to race 65 proceeding from Andecha can be explained by a single dominant gene located on linkage group B1, corresponding to the Co-1 gene. The recombination between the resistance speciWcities proceeding from A252 agrees with the assumption that total resistance to races 6, 31, 38, 39, 65, and 357, is organized in two clusters. One cluster, located on B4 linkage group, includes individual genes for speciWc resistance to races 6, 38, 39, and 357. The second cluster is located on linkage group B11 and includes individual genes for speciWc resistance to races 6, 31, 38, 39, and 65. These two clusters correspond to genes Co-3/Co-9 and Co-2, respectively. It is concluded that most anthracnose resistance Co- genes, previously described as single major genes conferring resistance to several races, could be organized as clusters of diVerent genes conferring race-speciWc resistance