bZIP67 Regulates the Omega-3 Fatty Acid Content of Arabidopsis Seed Oil by Activating FATTY ACID DESATURASE3

Arabidopsis thaliana seed maturation is accompanied by the deposition of storage oil, rich in the essential ω-3 polyunsaturated fatty acid α-linolenic acid (ALA). The synthesis of ALA is highly responsive to the level of FATTY ACID DESATURASE3 (FAD3) expression, which is strongly upregulated during...

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Bibliographic Details
Published in:The Plant cell 2013-08, Vol.25 (8), p.3104-3116
Main Authors: Mendes, Ana, Kelly, Amélie A., van Erp, Harrie, Shaw, Eve, Powers, Stephen J., Kurup, Smita, Eastmond, Peter J.
Format: Article
Language:English
Subjects:
Arabidopsis - enzymology
Arabidopsis - genetics
Arabidopsis - metabolism
Arabidopsis Proteins - genetics
Arabidopsis Proteins - metabolism
Basic-Leucine Zipper Transcription Factors - genetics
Basic-Leucine Zipper Transcription Factors - metabolism
DNA
DNA, Bacterial - genetics
Enzyme Activation
Fatty Acid Desaturases - genetics
Fatty Acid Desaturases - metabolism
Fatty acids
Fatty Acids, Omega-3 - metabolism
Gene expression regulation
Gene Expression Regulation, Plant
Genes
Genotypes
Lipids
Models, Biological
Mutation - genetics
Organ Size
Phosphatidylcholines - metabolism
Plant cells
Plant Oils - metabolism
Plants
Polymerase chain reaction
Promoter Regions, Genetic - genetics
Protein Binding - genetics
Seed Storage Proteins - genetics
Seed Storage Proteins - metabolism
Seeds - genetics
Seeds - metabolism
Transcriptional Activation - genetics
Transfection
Triglycerides - metabolism
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Summary:Arabidopsis thaliana seed maturation is accompanied by the deposition of storage oil, rich in the essential ω-3 polyunsaturated fatty acid α-linolenic acid (ALA). The synthesis of ALA is highly responsive to the level of FATTY ACID DESATURASE3 (FAD3) expression, which is strongly upregulated during embryogenesis. By screening mutants in LEAFY COTYLEDON1 (LEC1)—inducible transcription factors using fatty acid profiling, we identified two mutants (lec1-like and bzip67) with a seed lipid phenotype. Both mutants share a substantial reduction in seed ALA content. Using a combination of in vivo and in vitro assays, we show that bZIP67 binds G-boxes in the FAD3 promoter and enhances FAD3 expression but that activation is conditional on bZIP67 association with LEC1-LIKE (L1L) and NUCLEAR FACTOR-YC2 (NF-YC2). Although FUSCA3 and ABSCISIC ACID INSENSITIVE3 are required for L1L and bZIP67 expression, neither protein is necessary for [bZIP67:L1L:NF-YC2] to activate FAD3. We conclude that a transcriptional complex containing L1L, NF-YC2, and bZIP67 is induced by LEC1 during embryogenesis and specifies high levels of ALA production for storage oil by activating FAD3 expression.
ISSN:1040-4651
1532-298X
DOI:10.1105/tpc.113.116343