The Ethiopian grain teff (Eragrostis tef) is an economically and culturally important grain in the Horn of Africa, where it is most commonly grown by small scale farmers and has been domesticated to maintain consistent yields in poor conditions with low rainfall and less management. Advances in teff breeding have been slow due to its high selfing rate and lack of genetic resources. The goal of this work was to assemble a manageable panel of teff germplasm with maximum genetic diversity, leverage field phenotyping to identify marker trait associations, and share these tools and resources to advance teff breeding. Here, we describe the construction and genotyping of the Teff Association Panel (TAP), consisting of 265 cultivars and farmer varieties, as well as the wild progenitor Eragrostis pilosa. Using whole genome resequencing, we identified 21 million single nucleotide polymorphisms and insertions/deletions across the diversity panel, and used this panel to confirm the wild progenitor of teff, survey the genetic diversity and domestication history, and identify genetic loci underlying important agronomic traits. We grew the TAP in the field at Michigan State University in 2021 and 2022 to evaluate for lodging susceptibility, panicle architecture, plant height, days to heading, culm width, average panicle weight, average seed weight per panicle, seed color, and 12 seed mineral nutrients. The associations between agronomic and nutritional traits were evaluated to determine which traits play a critical role in lodging susceptibility and seed mineral nutrient content in teff. We detected a high correlation between panicle architecture and lodging susceptibility, and found that accessions with open panicle architectures lodged more consistently. We also confirmed the high nutritional value of teff by conducting the first large-scale analysis of teff seed mineral nutrients. The phenotypic data was harnessed to perform genome wide association for each trait and identify 50 loci significantly associated with 13 traits. The phenotypic variability and genomic resources developed from this work can be applied to rapidly improve teff agronomic efficiency.
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