title: Modification of fatty acid composition by over- and antisense-expression of a microsomal omega-3 fatty acid desaturase gene in transgenic tobacco.
abstract: omega-3 fatty acid desaturases, which catalyse the conversion of linoleic acid (18:2) to linolenic acid (18:3) in lipids, are located in the microsomes and plastid membranes. Transgenic tobacco plants were produced that express the transcripts of a tobacco microsomal omega-3 fatty acid desaturase gene (NtFad3) in antisense and sense orientations under the control of the cauliflower mosaic virus 35S promoter. The antisense construct has the 0.5-kb fragment of the NtFad3 cDNA containing a 3'-flanking region and a part of the coding region in antisense orientation. The antisense-transformant lines showed decreases of the steady-state NtFad3 mRNA level to 30% of the control plants. In these lines, the 18:3 content decreased to about 80% in root tissues and to about 70-80% in leaf tissues when compared with the control plants. The sense construct has the 1.4-kb full-length cDNA of NtFad3. In one of the sense-transformant lines, the NtFad3 mRNA level increased 8 times when compared with that of the control plants. In this line, the 18:3 content increased by about 1.5-fold in root tissues and by about 1.1-fold in leaf tissues. These results indicate that the up- and down-regulation of the transcript level in the microsomal omega-3 fatty acid desaturase gene is useful to modify the 18:3 content in the vegetative tissues of higher plants.
authors.affiliation: Department of Biology, Kyushu University, Fukuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hamada
authors.forename: H
authors.initials: H
authors.lastname: Kodama
authors.forename: M
authors.initials: M
authors.lastname: Nishimura
authors.forename: K
authors.initials: K
authors.lastname: Iba
mesh_terms: D016375:Antisense Elements (Genetics) / Q000235:genetics*; D017796:Caulimovirus / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D044943:Fatty Acid Desaturases / Q000096:biosynthesis / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics; D008861:Microsomes / Q000201:enzymology*; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D018749:RNA, Plant / Q000096:biosynthesis; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics*
chemical_list: D016375:Antisense Elements (Genetics); D018744:DNA, Plant; D012333:RNA, Messenger; D018749:RNA, Plant; D044943:Fatty Acid Desaturases; C078565:omega-3 fatty acid desaturase