title: Seed-specific over-expression of an Arabidopsis cDNA encoding a diacylglycerol acyltransferase enhances seed oil content and seed weight.
abstract: We recently reported the cloning and characterization of an Arabidopsis (ecotype Columbia) diacylglycerol acyltransferase cDNA (Zou et al., 1999) and found that in Arabidopsis mutant line AS11, an ethyl methanesulfonate-induced mutation at a locus on chromosome II designated as Tag1 consists of a 147-bp insertion in the DNA, which results in a repeat of the 81-bp exon 2 in the Tag1 cDNA. This insertion mutation is correlated with an altered seed fatty acid composition, reduced diacylglycerol acyltransferase (DGAT; EC 2.3.1.20) activity, reduced seed triacylglycerol content, and delayed seed development in the AS11 mutant. The effect of the insertion mutation on microsomal acyl-coenzyme A-dependent DGAT is examined with respect to DGAT activity and its substrate specificity in the AS11 mutant relative to wild type. We demonstrate that transformation of mutant AS11 with a single copy of the wild-type Tag1 DGAT cDNA can complement the fatty acid and reduced oil phenotype of mutant AS11. More importantly, we show for the first time that seed-specific over-expression of the DGAT cDNA in wild-type Arabidopsis enhances oil deposition and average seed weight, which are correlated with DGAT transcript levels. The DGAT activity in developing seed of transgenic lines was enhanced by 10% to 70%. Thus, the current study confirms the important role of DGAT in regulating the quantity of seed triacylglycerols and the sink size in developing seeds.
authors.affiliation: Seed Oil Biotechnology Group, National Research Council of Canada, Plant Biotechnology Institute, 110 Gymnasium Place, Saskatoon, Saskatchewan S7N 0W9, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Jako
authors.forename: A
authors.initials: A
authors.lastname: Kumar
authors.forename: Y
authors.initials: Y
authors.lastname: Wei
authors.forename: J
authors.initials: J
authors.lastname: Zou
authors.forename: D L
authors.initials: DL
authors.lastname: Barton
authors.forename: E M
authors.initials: EM
authors.lastname: Giblin
authors.forename: P S
authors.initials: PS
authors.lastname: Covello
authors.forename: D C
authors.initials: DC
authors.lastname: Taylor
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D000217:Acyltransferases / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D001483:Base Sequence; D017931:DNA Primers; D018076:DNA, Complementary; D051048:Diacylglycerol O-Acyltransferase; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D010938:Plant Oils / Q000032:analysis*; D012639:Seeds / Q000737:chemistry / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D000214:Acyl Coenzyme A; D017931:DNA Primers; D018076:DNA, Complementary; D010938:Plant Oils; D000217:Acyltransferases; D051048:Diacylglycerol O-Acyltransferase