title: Genome-Wide Association Study in Arabidopsis thaliana of Natural Variation in Seed Oil Melting Point: A Widespread Adaptive Trait in Plants.
abstract: Seed oil melting point is an adaptive, quantitative trait determined by the relative proportions of the fatty acids that compose the oil. Micro- and macro-evolutionary evidence suggests selection has changed the melting point of seed oils to covary with germination temperatures because of a trade-off between total energy stores and the rate of energy acquisition during germination under competition. The seed oil compositions of 391 natural accessions of Arabidopsis thaliana, grown under common-garden conditions, were used to assess whether seed oil melting point within a species varied with germination temperature. In support of the adaptive explanation, long-term monthly spring and fall field temperatures of the accession collection sites significantly predicted their seed oil melting points. In addition, a genome-wide association study (GWAS) was performed to determine which genes were most likely responsible for the natural variation in seed oil melting point. The GWAS found a single highly significant association within the coding region of FAD2, which encodes a fatty acid desaturase central to the oil biosynthesis pathway. In a separate analysis of 15 a priori oil synthesis candidate genes, 2 (FAD2 and FATB) were located near significant SNPs associated with seed oil melting point. These results comport with others' molecular work showing that lines with alterations in these genes affect seed oil melting point as expected. Our results suggest natural selection has acted on a small number of loci to alter a quantitative trait in response to local environmental conditions.
authors: From the US Vegetable Laboratory, Agricultural Research Service, United States Department of Agriculture, Charleston, SC 29414 (Branham); Department of Biology, Washington University, St. Louis, MO (Wright); Integrative Biology Department, University of Texas at Austin, Austin, TX (Branham, Reba, and Linder); and Division of Plant Sciences, University of Missouri, Columbia, MO (Morrison). sandra.branham@ars.usda.gov.
authors: Sandra E
authors: SE
authors: Branham
authors: From the US Vegetable Laboratory, Agricultural Research Service, United States Department of Agriculture, Charleston, SC 29414 (Branham); Department of Biology, Washington University, St. Louis, MO (Wright); Integrative Biology Department, University of Texas at Austin, Austin, TX (Branham, Reba, and Linder); and Division of Plant Sciences, University of Missouri, Columbia, MO (Morrison).
authors: Sara J
authors: SJ
authors: Wright
authors: From the US Vegetable Laboratory, Agricultural Research Service, United States Department of Agriculture, Charleston, SC 29414 (Branham); Department of Biology, Washington University, St. Louis, MO (Wright); Integrative Biology Department, University of Texas at Austin, Austin, TX (Branham, Reba, and Linder); and Division of Plant Sciences, University of Missouri, Columbia, MO (Morrison).
authors: Aaron
authors: A
authors: Reba
authors: From the US Vegetable Laboratory, Agricultural Research Service, United States Department of Agriculture, Charleston, SC 29414 (Branham); Department of Biology, Washington University, St. Louis, MO (Wright); Integrative Biology Department, University of Texas at Austin, Austin, TX (Branham, Reba, and Linder); and Division of Plant Sciences, University of Missouri, Columbia, MO (Morrison).
authors: Ginnie D
authors: GD
authors: Morrison
authors: From the US Vegetable Laboratory, Agricultural Research Service, United States Department of Agriculture, Charleston, SC 29414 (Branham); Department of Biology, Washington University, St. Louis, MO (Wright); Integrative Biology Department, University of Texas at Austin, Austin, TX (Branham, Reba, and Linder); and Division of Plant Sciences, University of Missouri, Columbia, MO (Morrison).
authors: C Randal
authors: CR
authors: Linder
mesh_terms: D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics; D044943:Fatty Acid Desaturases / Q000235:genetics; D005227:Fatty Acids / Q000737:chemistry*; D056726:Genetic Association Studies; D018525:Germination; D020641:Polymorphism, Single Nucleotide; D012639:Seeds / Q000737:chemistry*; D013869:Thiolester Hydrolases / Q000235:genetics; D044366:Transition Temperature
chemical_list: D029681:Arabidopsis Proteins; D005227:Fatty Acids; D044943:Fatty Acid Desaturases; C523310:FAD2 protein, Arabidopsis; C490837:FATB1 protein, Arabidopsis; D013869:Thiolester Hydrolases
keywords: GWAS.; adaptation; evolution; fatty acid composition