Genetic diversity and environmental adaptation in Ethiopian tef.

Orphan crops serve as essential resources for both nutrition and income in local communities and offer potential solutions to the challenges of food security and climate vulnerability. Tef [Eragrostis tef (Zucc.)], a small-grained allotetraploid, C4 cereal mainly cultivated in Ethiopia, stands out for its adaptability to marginal conditions and high nutritional value, which holds both local and global promise. Despite its significance, tef is considered an orphan crop due to limited genetic improvement efforts, reliance on subsistence farming, and its nutritional, economic, and cultural importance. Although pre-Semitic inhabitants of Ethiopia have cultivated tef for millennia (4000-1000 BCE), the genetic and environmental drivers of local adaptation remain poorly understood. To address this, we resequenced a diverse collection of traditional tef varieties to investigate their genetic structure and identify genomic regions under environmental selection using redundancy analysis, complemented by differentiation-based methods. We identified 145 loci associated with abiotic environmental factors, with minimal geographic influence observed in the genetic structure of the sample population. Overall, this work contributes to the broader understanding of local adaptation and its genetic basis in tef, providing insights that support efforts to develop elite germplasms with improved environmental resilience.