The Anthracnose, caused by Colletotrichum lindemuthianum (Sacc. and Magnus) Briosi and Cavara, is one of the most importante fungal disease of common bean. Several strategies have been used for its control, such as the use of pathogen-free seeds, chemical control and crop rotation. However, the most efficient method to control this disease is the use of resistant cultivars. Previous studies conducted by the Laboratory of Common Bean Breeding and Molecular Biology of the Nucleus of Research Applied to Agriculture (Laboratório de Melhoramento de Feijão Comum e de Biologia Molecular do Núcleo de Pesquisa Aplicada à Agricultura-NUPAGRI) revealed that the Andean cultivar Amendoim Cavalo is resistant to races 2, 7, 9, 19, 23, 39, 55, 65, 73, 89, 1545, 2047 and 3481 of C. lindemuthianum. The objective of this work was to characterize the genetic resistance to anthracnose in Amendoim Cavalo using inheritance and allelism tests. The results of inheritance tests in F2 generation of Amendoim Cavalo × PI 207262 cross, inoculated with 2047 race, fitted in a ratio of 3R:1S, proving the action of a single dominant gene in Amendoim Cavalo cultivar. Allelism tests demonstrated that the dominant gene present in Amendoim Cavalo is independent from the genes previously characterized. The authors propose the Co-AC symbol to designate the new resistant gene to C. lindemuthianum. The results show high contribution to breeding programs, once Amendoim Cavalo cultivar can be considered an important Andean source of resistance to C. lindemuthianum.

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ABSTRACT.The present study aimed to analyze, through 12 morpho-agronomic traits and 18 micro satellite loci, the genetic diversity in 17 common bean accessions from the Bean Germplasm Bank of the Center for Applied Agricultural Research of the State University of Maringá (BGF/Nupagri/UEM), in Paraná State, Brazil. Genetic diversity was assessed by joint analysis of phenotypic and genotypic characteristics using the Genetics platform of SAS software. To that end, a dissimilarity matrix was constructed based on the Jaccard index. This was used to generate a dendrogram via UPGMA hierarchical clustering, validated by multidimensional scaling and nonorthogonal principal components analysis. Based on genetic diversity analysis, the accessions were clustered into two large groups: one consisting of 11 accessions of Andean origin and the other containing six Mesoamerican accessions. The 17 accessions from the BGF/Nupagri/UEM were found to be an important source of genetic variability for inclusion in common bean breeding programs, contributing to the development of cultivars with desirable agronomic characteristics.

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Colletotrichum lindemuthianum is the causal agent of anthracnose in common bean. Favorable conditions for this disease might result in up to 100% yield losses. One of the main challenges for common bean producers and breeders still remains the management disease, since this pathogen exhibits a wide genetic variability probably due to its recombination sexual reproduction. The 5·8S gene and the flanking internal transcribed spacer regions (ITS1 and ITS2) of 40 different isolates of C. lindemuthianum collected in Brazil were amplified by PCR, and sequenced in order to determine genetic variability. The results revealed that 46.88% of SNPs were detected in the ITS1 region, while 53.12% of them were located in the ITS2 region. The genetic distance ranged from 0.000 to 0.169 between races. The greatest distance was observed between the races 10 and 73 with a value of 0.169, indicating a wide genetic variability between them. The phylogenetic tree was composed of three groups. Group I had five subgroups. Similar results were also observed through population structure analysis, which revealed the presence of three clusters. These results suggest that sequence analysis of ITS rDNA regions of C. lindemuthianum may be a valuable tool to identify this pathogen through design of specific primers.