title: Combined transgenic expression of Punica granatum conjugase (FADX) and FAD2 desaturase in high linoleic acid Arabidopsis thaliana mutant leads to increased accumulation of punicic acid.
abstract: Arabidopsis was engineered to produce 21.2 % punicic acid in the seed oil. Possible molecular factors limiting further accumulation of the conjugated fatty acid were investigated. Punicic acid (18:3Δ(9cis,11trans,13cis) ) is a conjugated linolenic acid isomer and is a main component of Punica granatum (pomegranate) seed oil. Medical studies have shown that punicic acid is a nutraceutical with anti-cancer and anti-obesity properties. It has been previously demonstrated that the conjugated double bonds in punicic acid are produced via the catalytic action of fatty acid conjugase (FADX), which is a homolog of the oleate desaturase. This enzyme catalyzes the conversion of the Δ(12)-double bond of linoleic acid (18:2Δ(9cis,12cis) ) into conjugated Δ(11trans) and Δ(13cis) -double bonds. Previous attempts to produce punicic acid in transgenic Arabidopsis thaliana seeds overexpressing P. granatum FADX resulted in a limited accumulation of punicic acid of up to 4.4 %, accompanied by increased accumulation of oleic acid (18:1∆(9cis) ), suggesting that production of punicic acid in some way inhibits the activity of oleate desaturase (Iwabuchi et al. 2003). In the current study, we applied a new strategy to enhance the production of punicic acid in a high linoleic acid A. thaliana fad3/fae1 mutant background using the combined expression of P. granatum FADX and FAD2. This approach led to the accumulation of punicic acid at the level of 21 % of total fatty acids and restored the natural proportion of oleic acid observed in the A. thaliana fad3/fae1 mutant. In addition, we provide new insights into the high oleate phenotype and describe factors limiting the production of punicic acid in genetically engineered plants.
authors.affiliation: Alberta Innovates Phytola Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Agriculture/Forestry Centre, Edmonton, AB, T6G 2P5, Canada.
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Mietkiewska
authors.forename: Robin
authors.initials: R
authors.lastname: Miles
authors.forename: Aruna
authors.initials: A
authors.lastname: Wickramarathna
authors.forename: Ariff Firman
authors.initials: AF
authors.lastname: Sahibollah
authors.forename: Michael S
authors.initials: MS
authors.lastname: Greer
authors.forename: Guanqun
authors.initials: G
authors.lastname: Chen
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Weselake
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism*; D008042:Linolenic Acids / Q000096:biosynthesis*; D029561:Lythraceae / Q000201:enzymology* / Q000235:genetics; D010713:Phosphatidylcholines / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D012639:Seeds / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism; D011623:gamma-Glutamyl Hydrolase / Q000235:genetics / Q000378:metabolism*
chemical_list: D008042:Linolenic Acids; D010713:Phosphatidylcholines; D014280:Triglycerides; D044943:Fatty Acid Desaturases; C040448:delta-12 fatty acid desaturase; D011623:gamma-Glutamyl Hydrolase; C519714:punicic acid