title: Combinatorial Effects of Fatty Acid Elongase Enzymes on Nervonic Acid Production in Camelina sativa.
abstract: Very long chain fatty acids (VLCFAs) with chain lengths of 20 carbons and longer provide feedstocks for various applications; therefore, improvement of VLCFA contents in seeds has become an important goal for oilseed enhancement. VLCFA biosynthesis is controlled by a multi-enzyme protein complex referred to as fatty acid elongase, which is composed of β-ketoacyl-CoA synthase (KCS), β-ketoacyl-CoA reductase (KCR), β-hydroxyacyl-CoA dehydratase (HCD) and enoyl reductase (ECR). KCS has been identified as the rate-limiting enzyme, but little is known about the involvement of other three enzymes in VLCFA production. Here, the combinatorial effects of fatty acid elongase enzymes on VLCFA production were assessed by evaluating the changes in nervonic acid content. A KCS gene from Lunaria annua (LaKCS) and the other three elongase genes from Arabidopsis thaliana were used for the assessment. Five seed-specific expressing constructs, including LaKCS alone, LaKCS with AtKCR, LaKCS with AtHCD, LaKCS with AtECR, and LaKCS with AtKCR and AtHCD, were transformed into Camelina sativa. The nervonic acid content in seed oil increased from null in wild type camelina to 6-12% in LaKCS-expressing lines. However, compared with that from the LaKCS-expressing lines, nervonic acid content in mature seeds from the co-expressing lines with one or two extra elongase genes did not show further increases. Nervonic acid content from LaKCS, AtKCR and AtHCD co-expressing line was significantly higher than that in LaKCS-expressing line during early seed development stage, while the ultimate nervonic acid content was not significantly altered. The results from this study thus provide useful information for future engineering of oilseed crops for higher VLCFA production.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China; Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, United States of America.
authors.forename: Dongxin
authors.initials: D
authors.lastname: Huai
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.
authors.forename: Chunyu
authors.initials: C
authors.lastname: Zhang
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China; Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, United States of America.
authors.forename: Edgar B
authors.initials: EB
authors.lastname: Cahoon
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.
authors.forename: Yongming
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism*; D000214:Acyl Coenzyme A / Q000378:metabolism; D019607:Brassicaceae / Q000201:enzymology*; D000081031:Fatty Acid Elongases; D005229:Fatty Acids, Monounsaturated / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005818:Genetic Engineering; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000235:genetics
chemical_list: D000214:Acyl Coenzyme A; D005229:Fatty Acids, Monounsaturated; D010940:Plant Proteins; D012333:RNA, Messenger; C013147:nervonic acid; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases