|HAMABWE, SWIVIA - University Of Nairobi
|OTIENTO, NICHOLAS - University Of Nairobi
|SOLER-GARZON, ALVARO - Washington State University
|Miklas, Phillip - Phil
|PARKER, TRAVIS - University Of California, Davis
|CHEELO, PRIDE - University Of California, Davis
|KUWABO, KUWABO - University Of Zambia
|KAMFWA, KELVIN - University Of Zambia
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2023
Publication Date: 10/12/2023
Citation: Hamabwe, S., Otiento, N., Soler-Garzon, A., Miklas, P.N., Parker, T., Cheelo, P., Kuwabo, K., Kamfwa, K. 2023. Identification of quantitative trait loci for drought tolerance in Bukoba/ Kijivu Andean mapping population of common bean. Crop Science. 136:222. https://doi.org/10.1007/s00122-023-04463-2.
Interpretive Summary: Drought continues to plague dry bean production in East African countries including Zambia. The available dry bean germplasm in Zambia varies for tolerance to drought. But most bred materials in Zambia are susceptible to drought and result in low yield under such stresses. Unfortunately breeding for tolerance to drought is difficult because little is known about genetic resistance in dry bean to drought stresses in Zambia. This study investigates the genetics of drought tolerance segregating in a genetic population derived from a drought susceptible parent crossed to a drought resistant parent. The genetics of drought tolerance was studied in this population which was planted across four separate yield trials that were managed to simulate drought stress. Three independent genomic regions with significant influence on the inheritance of drought resistance were discovered in this population and two of the locations support genetic findings from previous studies. The three genomic 'hotspots' conditioning drought tolerance will provide breeders with targets for generating new cultivars with improved drought tolerance for Zambian dry bean growers.
Technical Abstract: Drought is a major production constraint of common bean worldwide. The objective of this study was to identify the Quantitative Trait Loci (QTL) for drought tolerance in an Andean population of Recombinant Inbred Lines (RILs). A total of 155 F5:7 RILs derived from a cross between Kijivu (drought tolerant) and Bukoba (drought susceptible) were evaluated for drought tolerance in field and pot experiments. Four field experiments were conducted at three locations, including the University of Zambia Research Farm, Golden Valley Agricultural Research Farm, and Kabwe Zambia Agricultural Research Institute Farm, in 2021 and 2022. All field trials were conducted in the dry season under irrigation. The 155 RILs were genotyped with 11,292 SNPs, and composite interval mapping was conducted to identify QTL for drought tolerance. Seed yield for Kijivu under drought stress was consistently higher than for Bukoba across all four field trials. A total of 71 QTL were identified for morphological, agronomic, and physiological traits under drought stress and non-stress conditions. However, the majority of these QTL were specific to drought stress. QTL “hotspots” for drought tolerance were identified on chromosomes Pv06, Pv07, and Pv10. Extensive co-localizations for morpho-agronomic traits under drought stress were observed at the three drought-tolerance QTL hotspots. Additionally, these three QTL hotspots overlapped with previously identified QTL for drought tolerance, while several other identified QTL are novel. If validated further, the three identified QTL hotspots could be used in marker-assisted selection for drought tolerance in common bean.