Abstract
The prevailing hypothesis on the biosynthesis of erucic acid in developing seeds is that oleic acid, produced in the plastid, is activated to oleoyl-coenzyme A (CoA) for malonyl-CoA-dependent elongation to erucic acid in the cytosol. Several in vivo-labeling experiments designed to probe and extend this hypothesis are reported here. To examine whether newly synthesized oleic acid is directly elongated to erucic acid in developing seeds of Brassica rapa L., embryos were labeled with [14C]acetate, and the ratio of radioactivity of carbon atoms C-5 to C-22 (de novo fatty acid synthesis portion) to carbon atoms C-1 to C-4 (elongated portion) of erucic acid was monitored with time. If newly synthesized 18:1 (oleate) immediately becomes a substrate for elongation to erucic acid, this ratio would be expected to remain constant with incubation time. However, if erucic acid is produced from a pool of preexisting oleic acid, the ratio of 14C in the 4 elongation carbons to 14C in the methyl-terminal 18 carbons would be expected to decrease with time. This labeling ratio decreased with time and, therefore, suggests the existence of an intermediate pool of 18:1, which contributes at least part of the oleoyl precursor for the production of erucic acid. The addition of 2-[3-chloro-5-(trifluromethyl)-2-pyridinyloxyphenoxy] propanoic acid, which inhibits the homodimeric acetyl-CoA carboxylase, severely inhibited the synthesis of [14C]erucic acid, indicating that essentially all malonyl-CoA for elongation of 18:1 to erucate was produced by homodimeric acetyl-CoA carboxylase. Both light and 2-[3-chloro-5-(trifluromethyl)-2-pyridinyloxyphenoxy]-propanoic acid increased the accumulation of [14C]18:1 and the parallel accumulation of [14C]phosphatidylcholine. Taken together, these results show an additional level of complexity in the biosynthesis of erucic acid.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 6
Claim · model-written summary
The labeling ratio decreased with time in Brassica rapa embryos.
- Taxon
- Brassica rapa L.
Brassica rapae1 - Outcome
- labeling ratioe0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This labeling ratio decreased with time”
e1“developing seeds of Brassica rapa L.”
Claim · model-written summary
The decreasing ratio suggests an intermediate 18:1 pool contributes oleoyl precursor for erucic acid.
- Taxon
- Brassica rapa L.Brassica rapae1
- Outcome
- oleoyl precursor for the production of erucic acide0
- Qualifier
- intermediate pool of 18:1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggests the existence of an intermediate pool of 18:1, which contributes at least part of the oleoyl precursor for the production of erucic acid”
e1“developing seeds of Brassica rapa L.”
Claim · model-written summary
The acetyl-CoA carboxylase inhibitor severely inhibited labeled erucic acid synthesis.
- Taxon
- Brassica rapa L.Brassica rapae1
- Treatment
- 2-[3-chloro-5-(trifluromethyl)-2-pyridinyloxyphenoxy] propanoic acide0
- Gene
- homodimeric acetyl-CoA carboxylasee0
- Outcome
- synthesis of [14C]erucic acide0
- Direction
- severely inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The addition of 2-[3-chloro-5-(trifluromethyl)-2-pyridinyloxyphenoxy] propanoic acid, which inhibits the homodimeric acetyl-CoA carboxylase, severely inhibited the synthesis of [14C]erucic acid”
e1“developing seeds of Brassica rapa L.”
Claim · model-written summary
The inhibition indicates homodimeric acetyl-CoA carboxylase produced essentially all malonyl-CoA used for elongation.
- Taxon
- Brassica rapa L.Brassica rapae1
- Gene
- homodimeric acetyl-CoA carboxylasee0
- Outcome
- malonyl-CoA for elongation of 18:1 to erucatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“indicating that essentially all malonyl-CoA for elongation of 18:1 to erucate was produced by homodimeric acetyl-CoA carboxylase”
e1“developing seeds of Brassica rapa L.”
Claim · model-written summary
Light increased accumulation of labeled 18:1 and phosphatidylcholine.
- Taxon
- Brassica rapa L.Brassica rapae1
- Treatment
- lighte0
- Outcome
- accumulation of [14C]18:1 and the parallel accumulation of [14C]phosphatidylcholinee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both light and 2-[3-chloro-5-(trifluromethyl)-2-pyridinyloxyphenoxy]-propanoic acid increased the accumulation of [14C]18:1 and the parallel accumulation of [14C]phosphatidylcholine”
e1“developing seeds of Brassica rapa L.”
Claim · model-written summary
The acetyl-CoA carboxylase inhibitor increased accumulation of labeled 18:1 and phosphatidylcholine.
- Taxon
- Brassica rapa L.Brassica rapae1
- Treatment
- 2-[3-chloro-5-(trifluromethyl)-2-pyridinyloxyphenoxy]-propanoic acide0
- Outcome
- accumulation of [14C]18:1 and the parallel accumulation of [14C]phosphatidylcholinee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both light and 2-[3-chloro-5-(trifluromethyl)-2-pyridinyloxyphenoxy]-propanoic acid increased the accumulation of [14C]18:1 and the parallel accumulation of [14C]phosphatidylcholine”
e1“developing seeds of Brassica rapa L.”
The same questions in other papers
light · molecular: metabolites · Brassica rapa (field mustard)Positive and negative results
16 papers in the same direction as this paper · 5 in the opposite direction
- negative
- no effect
- no effect
18 papers more in this group
See all 22 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.