Introgression of the anthracnose resistance genes into selected commercial bean varieties using molecular markers

The inheritance of anthracnose resistance of the common bean (Phaseolus vulgaris L.) differential cultivar G 2333 to Colletotrichum lindemuthianum race 3 was studied in crosses of G2333 with the susceptible cultivars K132, K20D and GLP 585. The segregation ratios of 63: 1 in the F2 segregants of these crosses indicate that resistance in G2333 to race 3 is controlled by three independent dominant genes. All these genes had had equal effects against race 3. SCAR markers; SAS 13, SH 18 and SBB 14 all linked to Co-42, and SAB 3 linked to Ca-5 were used in the introgression of the resistance genes into the susceptible varieties. On investigating the usefulness of these SCAR markers in the introgression of the resistance genes into the susceptible varieties, it was found that they worked differently in the different genetic backgrounds. This difference was anticipated to have been caused by the use of different progenitors from the original ones from which the molecular markers were developed. For each population, different genetic distances between the gene and the molecular marker may be observed even if related progenitors are involved. RAPD molecular markers were used to enhance selection of plants with Co-42 and Co-5 genes as genetically close as possible to recurrent parents. With the study populations, the genetic distances between the selected BC3F, lines and recurrent progenitor involved in the study varied from 7'T to 104 %. BC3F, lines carrying either the Co-42 gene, or Co-5 gene or a combination of the two genes and that were over 90% genetically similar to their respective recurrent parents were selected for advancement.