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Research Project: Genetic Enhancement of Watermelon, Broccoli, and Leafy Brassicas for Economically Important Traits

Location: Vegetable Research

Title: Genome-wide association study of Arabidopsis thaliana identifies determinants of natural variation in seed oil composition

Author
item Branham, Sandra
item Reba, A - University Of Texas
item Wright, S - Washington University
item Linder, C - University Of Texas

Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2015
Publication Date: 12/24/2015
Citation: Branham, S., Reba, A., Wright, S.J., Linder, C.R. 2015. Genome-wide association study of Arabidopsis thaliana identifies determinants of natural variation in seed oil composition. Journal of Heredity. doi:10.1093/jhered/esv100.

Interpretive Summary: The fatty acids found in oil seeds provide a renewable source of highly reduced carbon for human consumption, industrial petrochemical replacement and biodiesel. Currently, 160 million metric tonnes of plant oils are being produced globally and demand will only increase due to a growing population, dwindling petroleum supplies and the low carbon dioxide impact of biofuels. These varied uses of seed oils require different optimal fatty acid compositions, the relative proportions of the fatty acids found in the seed oils. An ARS scientist at the U.S. Vegetable Laboratory in Charleston, South Carolina, is in collaboration with scientists at the University of Texas at Austin and has identified genes associated with variation in fatty acid proportions. These genes are of great interest to plant geneticists and breeders working in public and private industry research groups because they can be targeted in efforts to breed or bioengineer plants with fatty acid compositions that are desirable for food, industry, or biofuel uses.

Technical Abstract: The renewable source of highly reduced carbon provided by plant triacylglycerols fills an ever increasing demand for food, biodiesel and industrial chemicals. Each of these uses requires different compositions of fatty acid proportions in seed oils. Identifying the genes responsible for variation in seed oil composition in nature provides targets for bioengineering fatty acid proportions optimized for various industrial and nutrition goals. Here, we characterized the seed oil composition of 391 worldwide, wild accessions of Arabidopsis thaliana and performed a genome-wide association study of the nine major fatty acids in the seed oil and four composite measures of the fatty acids. Sixty-five SNPs were significantly associated with these traits, and 140 seed-expressed, a posteriori candidate genes were linked to them. Seven of these genes are involved in lipid metabolism or transport. Two of the lipid metabolism genes confirm previous molecular work that demonstrated their effects on seed oil composition, while the remaining five will require validation. Eleven of the genes encode regulatory products, including six transcription factors and five kinases. The vast majority of the candidate genes have never been implicated in lipid metabolism and represent potential new targets for bioengineering.