Agronomic Performance, Stability Analysis and Evaluation of Anthracnose Disease Resistance of Common Bean Lines Derived by Marker-Assisted Backcrossing in Uganda

Abstract

The present study focused on evaluating the agronomic performance, stability, and anthracnose resistance of common bean lines derived through Marker-Assisted Backcrossing in Uganda. Eight marker-assisted selection (MAS) backcross-derived bush bean lines with red seed types, alongside two checks, were evaluated in a randomized complete block design replicated two times in five locations for three consecutive crop-growing seasons in 2021 and 2022. The study aimed to identify lines with both high stable yields and enhanced resistance to anthracnose disease for potential release and utilization in future bean varietal development in Uganda. Agronomic traits, including days to 50% flowering, days to 90% physiological maturity, seed yield, seed yield components, and anthracnose disease reaction under natural infestation were assessed. The response to anthracnose disease was further assessed using six isolates of Colletotrichum lindemuthianum representing six different rac- es. Results indicated that the agronomic performances of the MAS back- cross-derived bush bean lines were statistically comparable to the recurrent parent NABE14. Specifically, six lines exhibited statistically equal to or higher performance than NABE14 in terms of seed yield, total number of seeds and number of pods per plant. The combined analysis of variance for seed yield showed significant (p < 0.05) effects for all the sources of variation except genotype × location interaction. Genotype main effect plus genotype × environment interaction (GGE) biplots explained 86.56% of the total observed variation for the seed yield. Within this, 64.12% was attributed to the first principal component (PC1), while the second principal component (PC2) explained 22.44%. UGKT-B157-4 emerged as the top-performing genotype, be- ing both high-yielding and stable. Positioned closer to the “ideal genotype” in the GGE biplot, UGKT-B157-4 outperformed others, winning in four out of the five test environments. Furthermore, UGKT-B157-4 exhibited resistance to anthracnose under both natural field infestation and artificial inoculation. The observed resistance pattern was similar to that of G2333, the donor parent in the backcross indicating the presence of the Co-42 and Co-5 anthracnose resistance genes in the derived line. In conclusion, UGKT-B157-4, identified as the best-performing and stable genotype, demonstrates promise for release and use in future bean varietal development in Uganda, offering a combination of high yields and enhanced anthracnose disease resistance. The study provides valuable insights into the potential of Marker-Assisted Back- crossing in improving common bean varieties in the region.