Anthracnose caused by Colletotrichum lindemuthianum is an important disease of common bean worldwide. In Uganda, two commercial bush bean varieties NABE13 and NABE14 with acceptable red seed types are highly susceptible. Our objective was to transfer the Co-42 and Co-5 anthracnose resistance genes from donor parent G2333 to NABE14 using a backcrossing program aided by molecular markers. The SH18 and SAB3 markers were used to identify BC1F1, BC2F1 and BC3F1 plants with the Co-42 and Co-5 resistance genes respectively, which were then crossed with the recurrent parent. Backcrossing was conducted upto BC4F1. The BC4F1 were then allowed to self-pollinate to produce BC4F2-3. The resulting BC4F2-3 progenies were first assessed for presence of the transferred resistance genes under natural infestation in the districts of Sheema and Kabale in Southwestern Uganda during 2017 first and second crop growing seasons. Then, the most superior progenies/lines with the NABE14 grain type identified from field evaluation were further assessed for the presence of the transferred resistance genes using the linked markers (SH18 and SAB3) and artificial inoculation with race 7 of Colletotrichum lindemuthianum. Basing on the results of marker screening and artificial inoculation with race 7 of Colletotrichum lindemuthianum we selected 18 promising backcross derived lines with the Co-42 and Co-5 genes. Seven promising backcross derived lines with only the Co-42 allele and seven with only the Co-5 allele were also obtained. From our study, marker assisted selection was useful to select for anthracnose resistance genes without using pathogen inoculation. The selected promising backcross derived lines will be subjected to further evaluation in order to identify those suitable for release and for use to improve anthracnose disease resistance.
Keywords: Biotic. Colletotrichum lindemuthianum. Phaseolus vulgaris. MAS. Seed borne