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The pathway of triacylglycerol synthesis through phosphatidylcholine in Arabidopsis produces a bottleneck for the accumulation of unusual fatty acids in transgenic seeds.
Plant J. 2011 Nov; 68(3):387-99.PJ

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.

Authors+Show Affiliations

Institute of Biological Chemistry, Washington State University, Clark Hall, Pullman, WA 99164-6340, USA.No affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

21711402

Citation

Bates, Philip D., and John Browse. "The Pathway of Triacylglycerol Synthesis Through Phosphatidylcholine in Arabidopsis Produces a Bottleneck for the Accumulation of Unusual Fatty Acids in Transgenic Seeds." The Plant Journal : for Cell and Molecular Biology, vol. 68, no. 3, 2011, pp. 387-99.
Bates PD, Browse J. The pathway of triacylglycerol synthesis through phosphatidylcholine in Arabidopsis produces a bottleneck for the accumulation of unusual fatty acids in transgenic seeds. Plant J. 2011;68(3):387-99.
Bates, P. D., & Browse, J. (2011). The pathway of triacylglycerol synthesis through phosphatidylcholine in Arabidopsis produces a bottleneck for the accumulation of unusual fatty acids in transgenic seeds. The Plant Journal : for Cell and Molecular Biology, 68(3), 387-99. https://doi.org/10.1111/j.1365-313X.2011.04693.x
Bates PD, Browse J. The Pathway of Triacylglycerol Synthesis Through Phosphatidylcholine in Arabidopsis Produces a Bottleneck for the Accumulation of Unusual Fatty Acids in Transgenic Seeds. Plant J. 2011;68(3):387-99. PubMed PMID: 21711402.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The pathway of triacylglycerol synthesis through phosphatidylcholine in Arabidopsis produces a bottleneck for the accumulation of unusual fatty acids in transgenic seeds. AU - Bates,Philip D, AU - Browse,John, Y1 - 2011/08/04/ PY - 2011/6/30/entrez PY - 2011/6/30/pubmed PY - 2012/3/17/medline SP - 387 EP - 99 JF - The Plant journal : for cell and molecular biology JO - Plant J VL - 68 IS - 3 N2 - 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. SN - 1365-313X UR - https://www.unboundmedicine.com/medline/citation/21711402/The_pathway_of_triacylglycerol_synthesis_through_phosphatidylcholine_in_Arabidopsis_produces_a_bottleneck_for_the_accumulation_of_unusual_fatty_acids_in_transgenic_seeds_ L2 - https://doi.org/10.1111/j.1365-313X.2011.04693.x DB - PRIME DP - Unbound Medicine ER -