Genome-Wide Association Study of Drought Resistance in Cultivated Sunflower Seedlings

Of all abiotic stresses that negatively impact crop productivity, drought is considered to be the most devastating. Functionally, resistance to water deficits have been well characterized through osmotic adjustment, early flowering, and improved water uptake strategies, however the underlying genetic mechanisms governing these strategies are still poorly understood. In the last decade, an appreciable genomic and transcriptomic effort has taken place to elucidate the mechanisms underlying drought resistance in both crop and model plant species, but little of this work has translated to improved breeding efforts. To address this concern, this project capitalized on the cultivated sunflower (Helianthus annuus) association mapping population, stressing and screening sunflower seedlings to identify marker-trait associations in relation to drought resistance. The osmotica polyethylene glycol 6000 was used, over a traditional drydown, to facilitate a controlled and reproducible drought effect. Though this project is still ongoing, we have assessed phenotypic variation for 15 quantitative seedling traits, most focusing on 2D root architecture and development. Once these phenotypes are fully processed, marker-trait associations will be run to identify genes and genomic regions of interest using standard genome-wide association protocols.