Abstract
BACKGROUND: Flax (Linum usitatissimum L.) is an agriculturally important crop with seed oil enriched in α-linolenic acid (18:3 (cisΔ9, 12, 15); ALA). This polyunsaturated fatty acid (PUFA) is the major determinant for the quality of flax seed oil in food, nutraceuticals and industrial applications. The recently identified enzyme: phosphatidylcholine diacylglycerol cholinephosphotransferase (PDCT), catalyzes the interconversion between phosphatidylcholine (PC) and diacylglycerol (DAG), and has been shown to play an important role in PUFA accumulation in Arabidopsis thaliana seeds. METHODS: Two flax PDCT genes were identified using homology-based approach. RESULTS: In this study, we describe the isolation and characterization of two PDCT genes from flax (LuPDCT1 and LuPDCT2) with very high nucleotide sequence identity (97%) whose deduced amino acid sequences exhibited approximately 55% identity with that of A. thaliana PDCT (AtROD1). The genes encoded functionally active enzymes that were strongly expressed in developing embryos. Complementation studies with the A. thaliana rod1 mutant demonstrated that the flax PDCTs were capable of restoring PUFA levels in planta. Furthermore, PUFA levels increased in Saccharomyces cerevisiae when the flax PDCTs were co-expressed with FATTY ACID DESATURASES (FADs), FAD2 and FAD3, while seed-specific expression of LuPDCT1 and LuPDCT2 in A. thaliana resulted in 16.4% and 19.7% increases in C18-PUFAs, respectively, with a concomitant decrease in the proportion of oleic acid (18:1 (cisΔ9); OA). CONCLUSIONS: The two novel PDCT homologs from flax are capable of increasing C18-PUFA levels substantially in metabolically engineered yeast and transgenic A. thaliana seeds. These flax PDCT proteins appear to play an important dual role in the determination of PUFA content by efficiently channelling monounsaturated FAs into PC for desaturation and moving the resulting PUFAs out of PC for subsequent use in TAG synthesis. These results indicate that flax PDCTs would be useful for bioengineering of oil crops to increase PUFA levels for applications in human food and nutritional supplements, animal feed and industrial bioproducts.
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Claims 11
Claim · model-written summary
Two flax PDCT genes, LuPDCT1 and LuPDCT2, were isolated and share 97% nucleotide sequence identity.
- Taxon
- flax
Linum usitatissimume0 - Gene
- LuPDCT1 and LuPDCT2e0
- Outcome
- nucleotide sequence identitye0
- Value
- 97%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“flax”
e0“isolation and characterization of two PDCT genes from flax (LuPDCT1 and LuPDCT2) with very high nucleotide sequence identity (97%)”
Claim · model-written summary
The deduced amino acid sequences of the flax PDCTs showed approximately 55% identity with A. thaliana PDCT (AtROD1).
- Taxon
- flaxLinum usitatissimumt0
- Outcome
- identity with that of A. thaliana PDCTe0
- Value
- 55%e0
- Qualifier
- approximatelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“flax”
e0“deduced amino acid sequences exhibited approximately 55% identity with that of A. thaliana PDCT (AtROD1)”
Claim · model-written summary
The two flax PDCT genes encoded functionally active enzymes.
- Taxon
- flaxLinum usitatissimumt0
- Outcome
- functionally active enzymese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“flax”
e0“The genes encoded functionally active enzymes”
Claim · model-written summary
The flax PDCT genes were strongly expressed in developing embryos.
- Taxon
- flaxLinum usitatissimumt0
- Organ / stage
- developing embryose0
- Outcome
- strongly expressede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“flax”
e0“enzymes that were strongly expressed in developing embryos”
Claim · model-written summary
Complementation of the A. thaliana rod1 mutant showed that the flax PDCTs were capable of restoring PUFA levels in planta.
- Taxon
- A. thaliana
Arabidopsis thalianae0 - Material
- rod1 mutante0
- Treatment
- flax PDCTse0
- Outcome
- PUFA levelse0
- Direction
- restoringe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Complementation studies with the A. thaliana rod1 mutant demonstrated that the flax PDCTs were capable of restoring PUFA levels in planta”
Claim · model-written summary
PUFA levels increased in Saccharomyces cerevisiae when the flax PDCTs were co-expressed with FAD2 and FAD3.
- Taxon
- Saccharomyces cerevisiae
Saccharomyces cerevisiaee0 - Treatment
- flax PDCTse0
- Outcome
- PUFA levelse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PUFA levels increased in Saccharomyces cerevisiae when the flax PDCTs”
Claim · model-written summary
Seed-specific expression of LuPDCT1 in A. thaliana increased C18-PUFAs by 16.4%.
- Taxon
- A. thalianaArabidopsis thalianae0
- Treatment
- seed-specific expressione0
- Gene
- LuPDCT1e0
- Outcome
- C18-PUFAse0
- Direction
- increasese0
- Value
- 16.4%e0
Not reportedOrgan / stageComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seed-specific expression of LuPDCT1 and LuPDCT2 in A. thaliana resulted in 16.4% and 19.7% increases in C18-PUFAs”
Claim · model-written summary
Seed-specific expression of LuPDCT2 in A. thaliana increased C18-PUFAs by 19.7%.
- Taxon
- A. thalianaArabidopsis thalianae0
- Treatment
- seed-specific expressione0
- Gene
- LuPDCT2e0
- Outcome
- C18-PUFAse0
- Direction
- increasese0
- Value
- 19.7%e0
Not reportedOrgan / stageComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“seed-specific expression of LuPDCT1 and LuPDCT2 in A. thaliana resulted in 16.4% and 19.7% increases in C18-PUFAs”
Claim · model-written summary
Seed-specific expression of the flax PDCTs in A. thaliana was accompanied by a decrease in the proportion of oleic acid.
Not reportedTaxonTreatmentComparator
Verbatim
e0“a concomitant decrease in the proportion of oleic acid”
Claim · model-written summary
The flax PDCT proteins appear to play a dual role in determining PUFA content.
- Taxon
- flaxLinum usitatissimume0
- Gene
- flax PDCT proteinse0
- Outcome
- PUFA contente0
- Qualifier
- appear to play an important dual rolee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These flax PDCT proteins appear to play an important dual role in the determination of PUFA content”
Claim · model-written summary
Flax PDCTs would be useful for bioengineering oil crops to increase PUFA levels.
Verbatim
e0“flax PDCTs would be useful for bioengineering of oil crops to increase PUFA levels”