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Lipidomic analysis of Arabidopsis seed genetically engineered to contain DHA.

Zhou XR, Callahan DL, Shrestha P, Liu Q, Petrie JR, Singh SP - Front Plant Sci (2014)

Bottom Line: 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.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.Trace amounts of di-DHA PC and tri-DHA TAG were identified and confirmed by high resolution MS/MS.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.


Total ion chromatogram from multiple reaction monitoring (MRM) of the triacylglycerol (TAG) species containing 20:1 or DHA from the WT and the GA7 Arabidopsis seeds.
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Figure 7: Total ion chromatogram from multiple reaction monitoring (MRM) of the triacylglycerol (TAG) species containing 20:1 or DHA from the WT and the GA7 Arabidopsis seeds.

Mentions: DHA-containing TAG species were only found in the GA7 developing or mature seeds. The accumulation of LC-PUFA-containing TAG was at the expense of 20:1-containing TAG (Figure 7). This is in line with previous results reported for total lipids from the GA7 seeds showing that 20:1 was significantly reduced (Petrie et al., 2012). In GA7, most of the 20:1-containing TAG species were reduced when compared to WT, except for the TAG species that also contained ALA or LC-PUFA. For example, TAG 20:1/34:3 (TAG 20:1/16:0/18:3) and TAG 20:1/36:6 (TAG 20:1/18:3/18:3) were increased in GA7 compared to WT (Figure 8A). SDA-, EPA- and DHA-containing TAGs were only found in the GA7 developing or mature seeds. As expected, TAG species 20:1/40:5 to 20:1/40:10, consisting of 20:1 plus LC-PUFA beyond 20:3 in the pathway, were absent in WT. This is in contrast to their accumulation, although at low levels in GA7. The highest 20:1-containing TAG species in GA7 were TAG 20:1/36:2 and 20:1/36:6.


Lipidomic analysis of Arabidopsis seed genetically engineered to contain DHA.

Zhou XR, Callahan DL, Shrestha P, Liu Q, Petrie JR, Singh SP - Front Plant Sci (2014)

Total ion chromatogram from multiple reaction monitoring (MRM) of the triacylglycerol (TAG) species containing 20:1 or DHA from the WT and the GA7 Arabidopsis seeds.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150447&req=5

Figure 7: Total ion chromatogram from multiple reaction monitoring (MRM) of the triacylglycerol (TAG) species containing 20:1 or DHA from the WT and the GA7 Arabidopsis seeds.
Mentions: DHA-containing TAG species were only found in the GA7 developing or mature seeds. The accumulation of LC-PUFA-containing TAG was at the expense of 20:1-containing TAG (Figure 7). This is in line with previous results reported for total lipids from the GA7 seeds showing that 20:1 was significantly reduced (Petrie et al., 2012). In GA7, most of the 20:1-containing TAG species were reduced when compared to WT, except for the TAG species that also contained ALA or LC-PUFA. For example, TAG 20:1/34:3 (TAG 20:1/16:0/18:3) and TAG 20:1/36:6 (TAG 20:1/18:3/18:3) were increased in GA7 compared to WT (Figure 8A). SDA-, EPA- and DHA-containing TAGs were only found in the GA7 developing or mature seeds. As expected, TAG species 20:1/40:5 to 20:1/40:10, consisting of 20:1 plus LC-PUFA beyond 20:3 in the pathway, were absent in WT. This is in contrast to their accumulation, although at low levels in GA7. The highest 20:1-containing TAG species in GA7 were TAG 20:1/36:2 and 20:1/36:6.

Bottom Line: 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.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.Trace amounts of di-DHA PC and tri-DHA TAG were identified and confirmed by high resolution MS/MS.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.