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

MAIN CONCLUSION:

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: Elzbieta Mietkiewska, Robin Miles, Aruna Wickramarathna, Ariff Firman Sahibollah, Michael S Greer, Guanqun Chen, Randall J Weselake
• Journal: Planta (Planta) Vol. 240 Issue 3 Pg. 575-83 (Sep 2014) ISSN: 1432-2048 [Electronic] Germany
• PMID: 25000918 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Linolenic Acids
• Phosphatidylcholines
• Triglycerides
• Fatty Acid Desaturases
• delta-12 fatty acid desaturase
• gamma-Glutamyl Hydrolase
• punicic acid

Topics

• Arabidopsis (metabolism)
• Fatty Acid Desaturases (genetics, metabolism)
• Linolenic Acids (biosynthesis)
• Lythraceae (enzymology, genetics)
• Phosphatidylcholines (metabolism)
• Plants, Genetically Modified (metabolism)
• Seeds (metabolism)
• Triglycerides (metabolism)
• gamma-Glutamyl Hydrolase (genetics, metabolism)