title: Two Acyltransferases Contribute Differently to Linolenic Acid Levels in Seed Oil.
abstract: Acyltransferases are key contributors to triacylglycerol (TAG) synthesis and, thus, are of great importance for seed oil quality. The effects of increased or decreased expression ofACYL-COENZYME A:DIACYLGLYCEROL ACYLTRANSFERASE1(DGAT1) orPHOSPHOLIPID:DIACYLGLYCEROL ACYLTRANSFERASE(PDAT) on seed lipid composition were assessed in severalCamelina sativalines. Furthermore, in vitro assays of acyltransferases in microsomal fractions prepared from developing seeds of some of these lines were performed. Decreased expression ofDGAT1led to an increased percentage of 18:3n-3 without any change in total lipid content of the seed. The tri-18:3 TAG increase occurred predominantly in the cotyledon, as determined with matrix-assisted laser desorption/ionization-mass spectrometry, whereas species with two 18:3n-3 acyl groups were elevated in both cotyledon and embryonal axis.PDAToverexpression led to a relative increase of 18:2n-6 at the expense of 18:3n-3, also without affecting the total lipid content. Differential distributions of TAG species also were observed in different parts of the seed. The microsomal assays revealed thatC.sativaseeds have very high activity of diacylglycerol-phosphatidylcholine interconversion. The combination of analytical and biochemical data suggests that the higher 18:2n-6 content in the seed oil of thePDAToverexpressors is due to the channeling of fatty acids from phosphatidylcholine into TAG before being desaturated to 18:3n-3, caused by the high activity of PDAT in general and by PDAT specificity for 18:2n-6. The higher levels of 18:3n-3 inDGAT1-silencing lines are likely due to the compensatory activity of a TAG-synthesizing enzyme with specificity for this acyl group and more desaturation of acyl groups occurring on phosphatidylcholine.
authors.affiliation: Albrecht-von-Haller Institute for Plant Sciences (S.M., C.H., I.F.) and Göttingen Center for Molecular Biosciences (I.F.), Department of Plant Biochemistry, Georg-August-University, 37077 Goettingen, Germany; sofia.marmon@slu.se.|Department of Plant Breeding, Swedish University of Agricultural Sciences, 230 53 Alnarp, Sweden (S.M., S.S.); and sofia.marmon@slu.se.|Center for Plant Lipid Research and BioDiscovery Institute, Department of Biological Sciences, University of North Texas, Denton, Texas 76203-5017 (D.S., K.C.) sofia.marmon@slu.se.
authors.forename: Sofia
authors.identifier: 0000-0001-6929-7859
authors.initials: S
authors.lastname: Marmon
authors.affiliation: Albrecht-von-Haller Institute for Plant Sciences (S.M., C.H., I.F.) and Göttingen Center for Molecular Biosciences (I.F.), Department of Plant Biochemistry, Georg-August-University, 37077 Goettingen, Germany.|Department of Plant Breeding, Swedish University of Agricultural Sciences, 230 53 Alnarp, Sweden (S.M., S.S.); and.|Center for Plant Lipid Research and BioDiscovery Institute, Department of Biological Sciences, University of North Texas, Denton, Texas 76203-5017 (D.S., K.C.).
authors.forename: Drew
authors.identifier: 0000-0003-3152-0394
authors.initials: D
authors.lastname: Sturtevant
authors.affiliation: Albrecht-von-Haller Institute for Plant Sciences (S.M., C.H., I.F.) and Göttingen Center for Molecular Biosciences (I.F.), Department of Plant Biochemistry, Georg-August-University, 37077 Goettingen, Germany.|Department of Plant Breeding, Swedish University of Agricultural Sciences, 230 53 Alnarp, Sweden (S.M., S.S.); and.|Center for Plant Lipid Research and BioDiscovery Institute, Department of Biological Sciences, University of North Texas, Denton, Texas 76203-5017 (D.S., K.C.).
authors.forename: Cornelia
authors.identifier: 0000-0001-8255-3255
authors.initials: C
authors.lastname: Herrfurth
authors.affiliation: Albrecht-von-Haller Institute for Plant Sciences (S.M., C.H., I.F.) and Göttingen Center for Molecular Biosciences (I.F.), Department of Plant Biochemistry, Georg-August-University, 37077 Goettingen, Germany.|Department of Plant Breeding, Swedish University of Agricultural Sciences, 230 53 Alnarp, Sweden (S.M., S.S.); and.|Center for Plant Lipid Research and BioDiscovery Institute, Department of Biological Sciences, University of North Texas, Denton, Texas 76203-5017 (D.S., K.C.).
authors.forename: Kent
authors.identifier: 0000-0003-0489-3072
authors.initials: K
authors.lastname: Chapman
authors.affiliation: Albrecht-von-Haller Institute for Plant Sciences (S.M., C.H., I.F.) and Göttingen Center for Molecular Biosciences (I.F.), Department of Plant Biochemistry, Georg-August-University, 37077 Goettingen, Germany.|Department of Plant Breeding, Swedish University of Agricultural Sciences, 230 53 Alnarp, Sweden (S.M., S.S.); and.|Center for Plant Lipid Research and BioDiscovery Institute, Department of Biological Sciences, University of North Texas, Denton, Texas 76203-5017 (D.S., K.C.).
authors.forename: Sten
authors.initials: S
authors.lastname: Stymne
authors.affiliation: Albrecht-von-Haller Institute for Plant Sciences (S.M., C.H., I.F.) and Göttingen Center for Molecular Biosciences (I.F.), Department of Plant Biochemistry, Georg-August-University, 37077 Goettingen, Germany.|Department of Plant Breeding, Swedish University of Agricultural Sciences, 230 53 Alnarp, Sweden (S.M., S.S.); and.|Center for Plant Lipid Research and BioDiscovery Institute, Department of Biological Sciences, University of North Texas, Denton, Texas 76203-5017 (D.S., K.C.).
authors.forename: Ivo
authors.identifier: 0000-0002-9888-7003
authors.initials: I
authors.lastname: Feussner
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D019607:Brassicaceae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D018548:Cotyledon / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008055:Lipids / Q000032:analysis; D010938:Plant Oils / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014280:Triglycerides / Q000032:analysis / Q000096:biosynthesis; D017962:alpha-Linolenic Acid / Q000032:analysis / Q000378:metabolism*
chemical_list: D000214:Acyl Coenzyme A; D005227:Fatty Acids; D007527:Isoenzymes; D008055:Lipids; D010938:Plant Oils; D010940:Plant Proteins; D014280:Triglycerides; D017962:alpha-Linolenic Acid; D000217:Acyltransferases