Tropentag, September 16 - 18, 2026, Göttingen "Towards multi-functional agro-ecosystems promoting climate-resilient futures"

Multi-environment qtl mapping reveals the genetic architecture of drought tolerance in elite african sorghum lines

¹Senegalese Institute for Agricultural Research, Senegal
²Senegalese Institute for Agricultural Research
³The International Maize and Wheat Improvement Center (CIMMYT)
⁴Senegalese Institute for Agricultural Research, Senegal
⁵Senegalese Institute for Agricultural Research, Senegal
⁶West African Centre for Crop Improvement (WACCI), Ghana
⁷Colorado State University (CSU), United States

Abstract

Drought severely limits sorghum productivity, and its impact is expected to intensify with climate change. This study leveraged a BCNAM population derived from crosses between three Senegalese elite varieties and the drought-tolerant parent B35 to identify genomic regions controlling grain yield, thousand grain weight (TGrW), and stress tolerance index (STI). Phenotypic data were collected over two growing seasons (2023 and 2024) across three contrasting locations under rain-fed, well-watered, and water-stressed conditions.
A total of nine QTLs for grain yield were detected primarily on chromosomes 2, 3, 6, and 9, but their expression was strongly environment-specific, revealing pronounced genotype-by-environment (GxE) interactions. These QTLs exhibited moderate to strong effects (LOD 3.85-7.50), underscoring the polygenic nature of yield under drought. Similarly, nine QTLs for thousand grain weight, identified on chromosomes 2 and 9, also displayed environment-dependent expression, aligning with the recognised influence of assimilate supply and water availability during grain filling.
Importantly, eight QTLs for the stress tolerance index on chromosome 2 were consistently detected across both seasons at one location, suggesting stable loci that contribute to drought resilience. Co-localised QTLs for TGrW and STI indicate possible pleiotropic effects or tight genetic linkage affecting yield components and stress adaptation simultaneously.
Candidate gene analysis revealed key genes linked to these traits, such as Sobic.002G339200 encoding chlorophyll a-b binding protein 3, which may enhance photosynthetic efficiency under stress, and Sobic.002G340100, an ADP-ribosylation factor linked to vesicle trafficking and stress signalling. Additional candidates involved in cell cycle regulation and hormonal pathways were also identified, providing insights into the biological mechanisms underpinning drought tolerance and grain development.
Functional enrichment highlighted pathways related to chloroplast function, phosphate metabolism, and secondary metabolite biosynthesis, reflecting critical physiological processes for sustaining yield under drought. These stable and environment-specific QTLs improve the understanding of drought adaptation in sorghum and provide valuable targets for marker-assisted breeding to develop resilient, high-yielding varieties.

Keywords: Drought, QTls, sorghum, stay green

Contact Address: Joseph Pascal Sène, Senegalese Institute for Agricultural Research, Dakar Ouest foire, rue 616, 61 Mbour-Senegal Nianing-Senegal, Senegal, e-mail: joseph15.senegmail.com