skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Tracking synthesis and turnover of triacylglycerol in leaves

Abstract

Triacylglycerol (TAG), typically represents <1% of leaf glycerolipids but can accumulate under stress and other conditions or if leaves are supplied with fatty acids, or in plants transformed with regulators or enzymes of lipid metabolism. To better understand the metabolism of TAG in leaves, pulse-chase radiolabelling experiments were designed to probe its synthesis and turnover. When Arabidopsis leaves were incubated with [ 14C]lauric acid (12:0), a major initial product was [ 14C]TAG. Thus, despite low steady-state levels, leaves possess substantial TAG biosynthetic capacity. The contributions of diacylglycerol acyltransferase1 and phospholipid:diacylglycerol acyltransferase1 to leaf TAG synthesis were examined by labelling of dgat1 and pdat1 mutants. The dgat1 mutant displayed a major (76%) reduction in [ 14C]TAG accumulation whereas pdat1 TAG labelling was only slightly reduced. Thus, DGAT1 has a principal role in TAG biosynthesis in young leaves. During a 4h chase period, radioactivity in TAG declined 70%, whereas the turnover of [ 14C]acyl chains of phosphatidylcholine (PC) and other polar lipids was much lower. Sixty percent of [ 14C]12:0 was directly incorporated into glycerolipids without modification, whereas 40% was elongated and desaturated to 16:0 and 18:1 by plastids. The unmodified [ 14C]12:0 and the plastid products of [ 14C]12:0 metabolism enteredmore » different pathways. Although plastid-modified 14C-labelled products accumulated in monogalactosyldiacylglycerol, PC, phosphatidylethanolamine, and diacylglcerol (DAG), there was almost no accumulation of [ 14C]16:0 and [ 14C]18:1 in TAG. Lastly, because DAG and acyl-CoA are direct precursors of TAG, the differential labelling of polar glycerolipids and TAG by [ 14C]12:0 and its plastid-modified products provides evidence for multiple subcellular pools of both acyl-CoA and DAG.« less

Authors:
 [1];  [1];  [1]
  1. Michigan State Univ., East Lansing, MI (United States). Great Lakes Bioenergy Research Center. Dept. of Plant Biology. Dept. of Energy
Publication Date:
Research Org.:
Michigan State Univ., East Lansing, MI (United States)
Sponsoring Org.:
USDOE; National Science Foundation (NSF); Swedish Council for Environment, Agricultural Sciences and Spatial Planning (Sweden)
OSTI Identifier:
1343070
Grant/Contract Number:
FC02-07ER64494; DBI-0701919; 2009–664
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Experimental Botany
Additional Journal Information:
Journal Volume: 66; Journal Issue: 5; Journal ID: ISSN 0022-0957
Publisher:
Oxford University Press
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; Acyl-CoA; DGAT; diacylglycerol acyltransferase; leaf TAG; lipids; triacylglycerol.

Citation Formats

Tjellstrom, Henrik, Strawsine, Merissa, and Ohlrogge, John B. Tracking synthesis and turnover of triacylglycerol in leaves. United States: N. p., 2015. Web. doi:10.1093/jxb/eru500.
Tjellstrom, Henrik, Strawsine, Merissa, & Ohlrogge, John B. Tracking synthesis and turnover of triacylglycerol in leaves. United States. doi:10.1093/jxb/eru500.
Tjellstrom, Henrik, Strawsine, Merissa, and Ohlrogge, John B. 2015. "Tracking synthesis and turnover of triacylglycerol in leaves". United States. doi:10.1093/jxb/eru500. https://www.osti.gov/servlets/purl/1343070.
@article{osti_1343070,
title = {Tracking synthesis and turnover of triacylglycerol in leaves},
author = {Tjellstrom, Henrik and Strawsine, Merissa and Ohlrogge, John B.},
abstractNote = {Triacylglycerol (TAG), typically represents <1% of leaf glycerolipids but can accumulate under stress and other conditions or if leaves are supplied with fatty acids, or in plants transformed with regulators or enzymes of lipid metabolism. To better understand the metabolism of TAG in leaves, pulse-chase radiolabelling experiments were designed to probe its synthesis and turnover. When Arabidopsis leaves were incubated with [14C]lauric acid (12:0), a major initial product was [14C]TAG. Thus, despite low steady-state levels, leaves possess substantial TAG biosynthetic capacity. The contributions of diacylglycerol acyltransferase1 and phospholipid:diacylglycerol acyltransferase1 to leaf TAG synthesis were examined by labelling of dgat1 and pdat1 mutants. The dgat1 mutant displayed a major (76%) reduction in [14C]TAG accumulation whereas pdat1 TAG labelling was only slightly reduced. Thus, DGAT1 has a principal role in TAG biosynthesis in young leaves. During a 4h chase period, radioactivity in TAG declined 70%, whereas the turnover of [14C]acyl chains of phosphatidylcholine (PC) and other polar lipids was much lower. Sixty percent of [14C]12:0 was directly incorporated into glycerolipids without modification, whereas 40% was elongated and desaturated to 16:0 and 18:1 by plastids. The unmodified [14C]12:0 and the plastid products of [14C]12:0 metabolism entered different pathways. Although plastid-modified 14C-labelled products accumulated in monogalactosyldiacylglycerol, PC, phosphatidylethanolamine, and diacylglcerol (DAG), there was almost no accumulation of [14C]16:0 and [14C]18:1 in TAG. Lastly, because DAG and acyl-CoA are direct precursors of TAG, the differential labelling of polar glycerolipids and TAG by [14C]12:0 and its plastid-modified products provides evidence for multiple subcellular pools of both acyl-CoA and DAG.},
doi = {10.1093/jxb/eru500},
journal = {Journal of Experimental Botany},
number = 5,
volume = 66,
place = {United States},
year = 2015,
month = 1
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 15works
Citation information provided by
Web of Science

Save / Share: