Document Detail

A cytosolic acyltransferase contributes to triacylglycerol synthesis in sucrose-rescued Arabidopsis seed oil catabolism mutants.
MedLine Citation:
PMID:  22760209     Owner:  NLM     Status:  MEDLINE    
Triacylglycerol (TAG) levels and oil bodies persist in sucrose (Suc)-rescued Arabidopsis (Arabidopsis thaliana) seedlings disrupted in seed oil catabolism. This study set out to establish if TAG levels persist as a metabolically inert pool when downstream catabolism is disrupted, or if other mechanisms, such as fatty acid (FA) recycling into TAG are operating. We show that TAG composition changes significantly in Suc-rescued seedlings compared with that found in dry seeds, with 18:2 and 18:3 accumulating. However, 20:1 FA is not efficiently recycled back into TAG in young seedlings, instead partitioning into the membrane lipid fraction and diacylglycerol. In the lipolysis mutant sugar dependent1and the β-oxidation double mutant acx1acx2 (for acyl-Coenzyme A oxidase), levels of TAG actually increased in seedlings growing on Suc. We performed a transcriptomic study and identified up-regulation of an acyltransferase gene, DIACYLGLYCEROL ACYLTRANSFERASE3 (DGAT3), with homology to a peanut (Arachis hypogaea) cytosolic acyltransferase. The acyl-Coenzyme A substrate for this acyltransferase accumulates in mutants that are blocked in oil breakdown postlipolysis. Transient expression in Nicotiana benthamiana confirmed involvement in TAG synthesis and specificity toward 18:3 and 18:2 FAs. Double-mutant analysis with the peroxisomal ATP-binding cassette transporter mutant peroxisomal ABC transporter1 indicated involvement of DGAT3 in the partitioning of 18:3 into TAG in mutant seedlings growing on Suc. Fusion of the DGAT3 protein with green fluorescent protein confirmed localization to the cytosol of N. benthamiana. This work has demonstrated active recycling of 18:2 and 18:3 FAs into TAG when seed oil breakdown is blocked in a process involving a soluble cytosolic acyltransferase.
M Luisa Hernández; Lynne Whitehead; Zhesi He; Valeria Gazda; Alison Gilday; Ekaterina Kozhevnikova; Fabián E Vaistij; Tony R Larson; Ian A Graham
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-07-03
Journal Detail:
Title:  Plant physiology     Volume:  160     ISSN:  1532-2548     ISO Abbreviation:  Plant Physiol.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-09-04     Completed Date:  2013-01-10     Revised Date:  2013-07-12    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  215-25     Citation Subset:  IM    
Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, United Kingdom.
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MeSH Terms
Agrobacterium tumefaciens / genetics,  metabolism
Amino Acid Sequence
Arabidopsis / enzymology*,  genetics
Arabidopsis Proteins / genetics,  metabolism
Arachis hypogaea / enzymology,  genetics
Cytosol / enzymology
Diacylglycerol O-Acyltransferase / genetics,  metabolism*
Fatty Acids / metabolism
Gene Expression Profiling / methods
Gene Expression Regulation, Plant
Genes, Plant
Lipid Metabolism*
Peroxisomes / enzymology
Plant Oils / metabolism*
Seedling / metabolism
Seeds / genetics,  metabolism*
Sequence Homology, Amino Acid
Sucrose / metabolism
Tobacco / genetics,  metabolism
Triglycerides / biosynthesis*
Grant Support
BB/D006856/1//Biotechnology and Biological Sciences Research Council
Reg. No./Substance:
0/Arabidopsis Proteins; 0/Fatty Acids; 0/Plant Oils; 0/Triglycerides; 57-50-1/Sucrose; EC O-Acyltransferase

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