Author(s)

Annuarite Uwera^1,2, John Nzungize Rusagara³, Susan Nchimbi Msolla¹, Augustine Musoni², Teshale Assefa^4*

¹Sokoine University of Agriculture, Morogoro, Tanzania.
²Rwanda Agriculture and Animal Resources Development Board, Kigali, Rwanda.
³International Crops Research Institute for the Semi-Arid Tropics, Bamako, Mali.
⁴Alliance Biodiversity International and CIAT, Arusha, Tanzania.

Anthracnose, caused by Colletotrichum lindemuthianum, is a major disease of common bean and results in high yield loss. Due to the high degree of pathogenic variability of the fungus and the continual emergence of new races, genetic resistance in the host is not durable. Gene pyramiding using Marker Assisted Selection (MAS) is proposed as a viable approach to improve the durability of major genes conditioning resistance to anthracnose. In this study a common bean line Urugezi x AND 1062 susceptible to anthracnose but already improved for Pythium root rot resistance was improved for anthracnose resistance through a backcross breeding program. Genotypic selection was done in Rubilizi laboratory in Kigali, Rwanada whereas phenotypic selection was conducted in an anthracnose hotspot at Rwerere, a research Centre of the Rwanda Agricultural and Animal Resources Development Board (RAB). Analysis of variance for effect of bean varieties and anthracnose isolates on disease expression showed significant differences (p < 0.001) among varieties and isolates and for the interaction between isolates and varieties. Developed BC₂F₁ plants were 41% of them resistant and 59% susceptible to anthracnose. However, the observed proportion of 26 resistants and 37 susceptible in BC₂F₁ plants didn’t fit the goodness of fit of the expected proportion of 75 resistants to 25 susceptible. Only 41% of BC₂F₁ plants inherited the resistance genes and were phenotypically resistant. Presence of SCAR-markers, SAB3 and SBB14, in the developed resistant lines h suggested successful resistance transfer of anthracnose resistance genes.

Anthracnose, Common Bean, Resistance Genes, Pythium Root Rot

Uwera, A. , Rusagara, J. , Msolla, S. , Musoni, A. and Assefa, T. (2021) Molecular Marker-Assisted Backcrossing of Anthracnose Resistance Genes into Common Beans (Phaseolus vulgaris L.) Varieties. American Journal of Plant Sciences, 12, 771-781. doi: 10.4236/ajps.2021.125053.