Black dry bean (Phaseolus vulgaris L.) germplasm accessions with resistance to prevalent races of Colletotrichum lindemuthianum in Canada

Genetic diversity of dry bean (Phaseolus vulgaris L.) in Canadian breeding programs is low. Cultivars, especially black beans, generally lack resistance to anthracnose. One hundred and fifty-five black bean accessions originating from twenty countries were evaluated for their resistance to races 73 and 105 of Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi & Cavara, the predominant races of the bean anthracnose pathogen in Canada. Artificial inoculation in growth chambers identified 39 accessions that were resistant to race 73, of which 33 were also resistant to race 105. Only one accession was susceptible to race 73 and resistant to 105. The resistant lines from the collection were also screened with genetic markers closely associated with known anthracnose resistance genes. At least one of the major resistance loci, Co-1, Co-2, Co-3, Co-4, and Co-5, was indicated to be present in all except four accessions. The majority of resistant accessions appeared to carry at least one or two major resistance loci. The black bean accessions with anthracnose resistance will provide much-needed breeding materials and expand genetic diversity for Canadian and international dry bean improvement.