title: Natural variation in seed very long chain fatty acid content is controlled by a new isoform of KCS18 in Arabidopsis thaliana.
abstract: Oil from oleaginous seeds is mainly composed of triacylglycerols. Very long chain fatty acids (VLCFAs) are major constituents of triacylglycerols in many seed oils and represent valuable feedstock for industrial purposes. To identify genetic factors governing natural variability in VLCFA biosynthesis, a quantitative trait loci (QTL) analysis using a recombinant inbred line population derived from a cross between accessions Bay-0 and Shahdara was performed in Arabidopsis thaliana. Two fatty acid chain length ratio (CLR) QTL were identified, with one major locus, CLR.2, accounting for 77% of the observed phenotypic variation. A fine mapping and candidate gene approach showed that a key enzyme of the fatty acid elongation pathway, the β-ketoacyl-CoA synthase 18 (KCS18), was responsible for the CLR.2 QTL detected between Bay-0 and Shahdara. Association genetics and heterologous expression in yeast cells identified a single point mutation associated with an alteration of KCS18 activity, uncovering the molecular bases for the modulation of VLCFA content in these two natural populations of Arabidopsis. Identification of this kcs18 mutant with altered activity opens new perspectives for the modulation of oil composition in crop plants.
authors.affiliation: INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, Versailles, France. sophie.jasinski@versailles.inra.fr
authors.forename: Sophie
authors.initials: S
authors.lastname: Jasinski
authors.forename: Alain
authors.initials: A
authors.lastname: Lécureuil
authors.forename: Martine
authors.initials: M
authors.lastname: Miquel
authors.forename: Olivier
authors.initials: O
authors.lastname: Loudet
authors.forename: Sylvain
authors.initials: S
authors.lastname: Raffaele
authors.forename: Marine
authors.initials: M
authors.lastname: Froissard
authors.forename: Philippe
authors.initials: P
authors.lastname: Guerche
mesh_terms: D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D003433:Crosses, Genetic; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D056726:Genetic Association Studies; D010641:Phenotype; D017354:Point Mutation; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D017434:Protein Structure, Tertiary; D040641:Quantitative Trait Loci; D012639:Seeds / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D005227:Fatty Acids; D020033:Protein Isoforms; D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase; C581828:KCS18 protein, Arabidopsis