title: Identification of functional BrFAD2-1 gene encoding microsomal delta-12 fatty acid desaturase from Brassica rapa and development of Brassica napus containing high oleic acid contents.
abstract: Microsomal delta-12 fatty acid desaturase (FAD2) functions in the first committed step of the biosynthesis of polyunsaturated fatty acids via the desaturation of oleic acid to linoleic acid. In this study, two FAD2 genes were identified through genome-wide analysis of Brassica rapa. One BrFAD2-1 gene harbors functional sequence information, but another BrFAD2-2 gene has mutations that generated a premature stop codon, rendering it nonfunctional. From a database of 120,000 B. rapa expressed sequence tags, we determined that all sequences coding for FAD2 corresponded to the BrFAD2-1 gene. The BrFAD2-1 protein was shown to share high sequence homology (71-99%) with FAD2 proteins from other plant species. An intron in the 5'-untranslated region and three histidine boxes in the protein, which are characteristic of plant FAD2 genes, have been well-conserved. BrFAD2-1 transcripts were detected in various organs of B. rapa. When a pBrFAD2-1:mRFP construct was introduced into tobacco epidermal cells, the fluorescent signal was noted in the endoplasmic reticulum. Ectopic expression of BrFAD2-1:mRFP complemented the Arabidopsis fad2-2 mutant. Finally, transgenic Korean rapeseed Tammi containing high oleic acid contents (78 mol%) was developed via the expression of the BrFAD2-1 gene in an antisense orientation. The data demonstrate that B. rapa harbors only one functional FAD2 that can be utilized for the development of the high-oleic acid Korean rapeseed cultivar Tammi, which might be useful for both human consumption and industrial applications.
authors.affiliation: Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, 500-757, Republic of Korea.
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Jung
authors.forename: Hyojin
authors.initials: H
authors.lastname: Kim
authors.forename: Young Sam
authors.initials: YS
authors.lastname: Go
authors.forename: Saet Buyl
authors.initials: SB
authors.lastname: Lee
authors.forename: Cheol-Goo
authors.initials: CG
authors.lastname: Hur
authors.forename: Hyun Uk
authors.initials: HU
authors.lastname: Kim
authors.forename: Mi Chung
authors.initials: MC
authors.lastname: Suh
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D001483:Base Sequence; D029688:Brassica napus / Q000201:enzymology / Q000235:genetics*; D029741:Brassica rapa / Q000201:enzymology / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D020224:Expressed Sequence Tags; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism*; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D019301:Oleic Acid / Q000096:biosynthesis*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D019301:Oleic Acid; D044943:Fatty Acid Desaturases; C040448:delta-12 fatty acid desaturase