title: Lipidomic analysis of Arabidopsis seed genetically engineered to contain DHA.
abstract: Metabolic engineering of omega-3 long-chain (≥C20) polyunsaturated fatty acids (ω3 LC-PUFA) in oilseeds has been one of the key targets in recent years. By expressing a transgenic pathway for enhancing the synthesis of the ω3 LC-PUFA docosahexaenoic acid (DHA) from endogenous α-linolenic acid (ALA), we obtained the production of fish oil-like proportions of DHA in Arabidopsis seed oil. Liquid chromatography-mass spectrometry (LC-MS) was used to characterize the triacylglycerol (TAG), diacylglycerol (DAG) and phospholipid (PL) lipid classes in the transgenic and wild type Arabidopsis seeds at both developing and mature stages. The analysis identified the appearance of several abundant DHA-containing phosphatidylcholine (PC), DAG and TAG molecular species in mature seeds. The relative abundances of PL, DAG, and TAG species showed a preferred combination of LC-PUFA with ALA in the transgenic seeds, where LC-PUFA were esterified in positions usually occupied by 20:1ω9. Trace amounts of di-DHA PC and tri-DHA TAG were identified and confirmed by high resolution MS/MS. Studying the lipidome in transgenic seeds provided insights into where DHA accumulated and combined with other fatty acids of neutral and phospholipids from the developing and mature seeds.
authors.affiliation: Food Futures National Research Flagship, Commonwealth Scientific and Industrial Research Organisation Canberra, ACT, Australia ; Plant Industry, Commonwealth Scientific and Industrial Research Organisation Canberra, ACT, Australia.
authors.forename: Xue-Rong
authors.initials: XR
authors.lastname: Zhou
authors.affiliation: Metabolomics Australia, School of Botany, University of Melbourne Melbourne, VIC, Australia ; Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences, Deakin University Melbourne, VIC, Australia.
authors.forename: Damien L
authors.initials: DL
authors.lastname: Callahan
authors.affiliation: Food Futures National Research Flagship, Commonwealth Scientific and Industrial Research Organisation Canberra, ACT, Australia.
authors.forename: Pushkar
authors.initials: P
authors.lastname: Shrestha
authors.affiliation: Food Futures National Research Flagship, Commonwealth Scientific and Industrial Research Organisation Canberra, ACT, Australia.
authors.forename: Qing
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Food Futures National Research Flagship, Commonwealth Scientific and Industrial Research Organisation Canberra, ACT, Australia.
authors.forename: James R
authors.initials: JR
authors.lastname: Petrie
authors.affiliation: Food Futures National Research Flagship, Commonwealth Scientific and Industrial Research Organisation Canberra, ACT, Australia.
authors.forename: Surinder P
authors.initials: SP
authors.lastname: Singh
keywords: Arabidopsis; LC-MS; Lipidomics; metabolic engineering; oilseed; triacylglycerol; ω3 LC-PUFA