Evolutionary Genomics of Abiotic Stress Resistance in Wild and Cultivated Sunflowers

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PI: John M. Burke (University of Georgia-Athens)Co-PIs: Lisa A. Donovan (University of Georgia-Athens), Loren H. Rieseberg (Indiana University), Khaled M. Bali (University of California Division of Agriculture & Natural Resources), Pedro Andrade-Sanchez (University of Arizona), and Jennifer M. Dechaine (Central Washington U.)Key Collaborators: Jeffrey W. White (USDA-ARS/Maricopa) and Nicolas B. Langlade (INRA, France)Wild and cultivated plants are regularly challenged by a variety of abiotic stresses resulting from factors such as drought, soil salinization, and low nutrient availability. These stresses affect plant growth and development and reduce crop productivity. Though wild plant populations have adapted to many of these challenges, crops are often less resilient. This is likely due to the occurrence of tradeoffs between stress resistance and overall growth/productivity, as well as the loss of genetic diversity during the domestication and breeding of crop plants. To combat stress-induced yield loss and improve food security, attention has turned to the development of stress-resistant crops, but such efforts require knowledge. An improved understanding of the mechanisms underlying abiotic stress resistance is thus needed to develop crops capable of feeding a rapidly growing population in the context of an increasingly variable climate, particularly as marginal lands are brought into production. The research conducted in this project will have important practical outcomes that will ultimately facilitate the production of more resilient crop plants. These outcomes include the production of actionable knowledge regarding the molecular and physiological mechanisms underlying resistance to abiotic stresses that limit agricultural productivity, the identification of favorable genetic variants that can be moved from wild populations into downstream breeding programs, and the development and distribution of valuable germplasm resources. This project will also provide educational opportunities for students at multiple levels, and from diverse backgrounds.This project involves a detailed investigation of the genomic and physiological basis of drought, salt, and low nutrient stress resistance in cultivated sunflower and its reproductively compatible, stress-adapted wild species that are potential donors of beneficial alleles. Sunflower is an ideal study system for this work because the productivity of cultivated sunflower is clearly limited by such stresses, while related wild species are adapted to life in a variety of extreme environments. The goals of this project are to: (1) assess resistance to drought, salt, and low nutrient stress and related traits in cultivated sunflower and its wild relatives using traditional and high-throughput phenotyping approaches; (2) associate variation in abiotic stress resistance and related traits in cultivated and wild sunflowers with specific genes, regulatory networks, and/or causal variants; (3) determine the mechanistic basis of stress resistance via in-depth physiological and transcriptomic characterization of genotypes with divergent stress responses; (4) identify suitable stress resistance alleles (i.e., those exhibiting resistance in multiple genetic backgrounds, ideally with minimal tradeoffs) for use in sunflower breeding programs; and (5) prepare students from diverse backgrounds for careers in the plants sciences. All germplasm resources will be made available via deposition in public repositories (e.g., USDA-GRIN) and the resulting data will be disseminated via peer-reviewed publications, public presentations, and deposition into relevant public databases including the sunflower genome database (http://www.sunflowergenome.org/), the HeliaGene sunflower database (http://www.heliagene.org/), GenBank (http://www.ncbi.nlm.nih.gov/genbank/), Phytozome (http://www.phytozome.net/), the Gene Expression Omnibus (http://ncbi.nlm.nih.gov/geo/), and Dryad (http://datadryad.org/).