Genetic Improvement, Genomic Resources Enrichment, and Phenotypic Diversity Assessment of Teff [Eragrostis tef (Zucc.) Trotter]: A Forage, Fodder, and Highly Nutritious and Gluten-free Grain Crop for Dryland Agriculture

Teff is gluten-free and nutritionally dense grain crop suitable for diverse agroclimatic conditions owing to its diverse genetic resources. Teff consumption and cultivation outside Ethiopia is becoming more prominent than before for the demand for teff, a gluten-free and nutritionally balanced whole grain is increasing. Despite teff having immense health and nutritional benefits, its productivity is lower than that of globally important cereal grain crops. Research intervention has been limited due to lack of interest in the crop. However, research in teff is gaining momentum with the application of cutting-edge biotechnological tools. This dissertation has five chapters. The first chapter provides an introduction about the agronomic and nutritional importance of teff and summarizes recent molecular genetic teff research. The second chapter summarizes the agronomic and morphological characterization of USDA-ARS teff collection based upon phenotypic traits gathered under greenhouse growth conditions. The characterization revealed the existence of huge genetic diversity within the available teff accessions. The third chapter describes the development of high-quality, haplotype-phased, and chromosome-level genome assembly of a highly drought tolerant teff accessions (PI-494237). The 40 chromosomes were phased into haplotype groups with the tetraploid genome encoding 130,325 gene models. The fourth chapter reports on the identification, characterization, and high-throughput transcriptome profiling of drought tolerant Teff accessions. Screening of the 368 USDA-ARS teff germplasm collection against acute and chronic water-deficit stress conditions identified two highly drought tolerant teff accessions (PI-494237 and PI-494455). Subsequent agronomic and physiological characterization and differential gene expression analysis identified unique and shared sets of genes that exhibited significantly increased or decreased relative transcript abundance following the imposition of water-deficit stress in drought-tolerant and relevant control accessions. The fifth chapter summarizes the main findings of this study and suggest research interventions with generic experimental plans targeting lodging. The current findings will enhance the agronomic and genomic resources of teff thereby contributing to the overall improvement of the crop using traditional breeding approaches and biotechnological interventions to overcome major production barriers such as lodging and drought tolerance