Abstract
Engineering of oilseed plants to accumulate unusual fatty acids (FAs) in seed triacylglycerol (TAG) requires not only the biosynthetic enzymes for unusual FAs but also efficient utilization of the unusual FAs by the host-plant TAG biosynthetic pathways. Competing pathways of diacylglycerol (DAG) and subsequent TAG synthesis ultimately affect TAG FA composition. The membrane lipid phosphatidylcholine (PC) is the substrate for many FA-modifying enzymes (desaturases, hydroxylases, etc.) and DAG can be derived from PC for TAG synthesis. The relative proportion of PC-derived DAG versus de novo synthesized DAG utilized for TAG synthesis, and the ability of each pathway to utilize unusual FA substrates, are unknown for most oilseed plants, including Arabidopsis thaliana. Through metabolic labeling experiments we demonstrate that the relative flux of de novo DAG into the PC-derived DAG pathway versus direct conversion to TAG is ∼14/1 in wild-type Arabidopsis. Expression of the Ricinus communis FA hydroxylase reduced the flux of de novo DAG into PC by ∼70%. Synthesis of TAG directly from de novo DAG did not increase, resulting in lower total synthesis of labeled lipids. Hydroxy-FA containing de novo DAG was rapidly synthesized, but it was not efficiently accumulated or converted to PC and TAG, and appeared to be in a futile cycle of synthesis and degradation. However, FA hydroxylation on PC and conversion to DAG allowed some hydroxy-FA to accumulate in sn-2 TAG. Therefore, the flux of DAG through PC represents a major bottleneck for the accumulation of unusual FAs in TAG of transgenic Arabidopsis seeds.
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Claims 7
Claim · model-written summary
In wild-type Arabidopsis the relative flux of de novo DAG into the PC-derived DAG pathway versus direct conversion to TAG is about 14 to 1.
- Taxon
- Arabidopsis
Arabidopsist0 - Material
- wild-typee0
- Outcome
- relative flux of de novo DAG into the PC-derived DAG pathway versus direct conversion to TAGe0
- Value
- ∼14/1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis”
e0“the relative flux of de novo DAG into the PC-derived DAG pathway versus direct conversion to TAG is ∼14/1 in wild-type Arabidopsis”
Claim · model-written summary
Expression of the Ricinus communis FA hydroxylase reduced the flux of de novo DAG into PC by about 70%.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Expression of the Ricinus communis FA hydroxylasee0
- Gene
- Ricinus communis FA hydroxylasee0
- Outcome
- flux of de novo DAG into PCe0
- Direction
- reducede0
- Value
- ∼70%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis”
e0“Expression of the Ricinus communis FA hydroxylase reduced the flux of de novo DAG into PC by ∼70%”
Claim · model-written summary
Synthesis of TAG directly from de novo DAG did not increase with hydroxylase expression.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Expression of the Ricinus communis FA hydroxylasee0
- Outcome
- Synthesis of TAG directly from de novo DAGe1
- Direction
- did not increasee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis”
e0“Expression of the Ricinus communis FA hydroxylase reduced the flux of de novo DAG into PC by ∼70%”
e1“Synthesis of TAG directly from de novo DAG did not increase”
Claim · model-written summary
Hydroxylase expression resulted in lower total synthesis of labeled lipids.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Expression of the Ricinus communis FA hydroxylasee0
- Outcome
- total synthesis of labeled lipidse1
- Direction
- lowere1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis”
e0“Expression of the Ricinus communis FA hydroxylase reduced the flux of de novo DAG into PC by ∼70%”
e1“resulting in lower total synthesis of labeled lipids”
Claim · model-written summary
Hydroxy-FA containing de novo DAG was rapidly synthesized but not efficiently accumulated or converted to PC and TAG, appearing to be in a futile cycle of synthesis and degradation.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- Hydroxy-FA containing de novo DAGe0
- Qualifier
- not efficiently accumulated or converted to PC and TAGe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis”
e0“Hydroxy-FA containing de novo DAG was rapidly synthesized, but it was not efficiently accumulated or converted to PC and TAG, and appeared to be in a futile cycle of synthesis and degradation”
Claim · model-written summary
FA hydroxylation on PC and conversion to DAG allowed some hydroxy-FA to accumulate in sn-2 TAG.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- hydroxy-FA to accumulate in sn-2 TAGe0
- Qualifier
- FA hydroxylation on PC and conversion to DAGe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis”
e0“FA hydroxylation on PC and conversion to DAG allowed some hydroxy-FA to accumulate in sn-2 TAG”
Claim · model-written summary
The authors conclude that DAG flux through PC is a major bottleneck for accumulation of unusual fatty acids in TAG of transgenic Arabidopsis seeds.
- Taxon
- ArabidopsisArabidopsise0
- Organ / stage
- seedse0
- Outcome
- accumulation of unusual FAs in TAGe0
- Qualifier
- flux of DAG through PC represents a major bottlenecke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the flux of DAG through PC represents a major bottleneck for the accumulation of unusual FAs in TAG of transgenic Arabidopsis seeds”
The same questions in other papers
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See all 45 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.