Reduced expression of FatA thioesterases in Arabidopsis affects the oil content and fatty acid composition of the seeds |
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Authors: | Antonio?J?Moreno-Pérez Mónica?Venegas-Calerón Fabián?E?Vaistij Joaquín?J?Salas Tony?R?Larson Rafael?Garcés Ian?A?Graham Email author" target="_blank">Enrique?Martínez-ForceEmail author |
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Institution: | 1.Instituto de la Grasa,Seville,Spain;2.Centre for Novel Agricultural Products, Department of Biology,University of York,York,UK |
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Abstract: | Acyl–acyl carrier protein (ACP) thioesterases are enzymes that control the termination of intraplastidial fatty acid synthesis
by hydrolyzing the acyl–ACP complexes. Among the different thioesterase gene families found in plants, the FatA-type fulfills a fundamental role in the export of the C18 fatty acid moieties that will be used to synthesize most plant
glycerolipids. A reverse genomic approach has been used to study the FatA thioesterase in seed oil accumulation by screening
different mutant collections of Arabidopsis thaliana for FatA knockouts. Two mutants were identified with T-DNA insertions in the promoter region of each of the two copies of FatA present in the Arabidopsis genome, from which a double FatA Arabidopsis mutant was made. The expression of both forms of FatA thioesterases was reduced in this double mutant (fata1 fata2), as was FatA activity. This decrease did not cause any evident morphological changes in the mutant plants, although the partial
reduction of this activity affected the oil content and fatty acid composition of the Arabidopsis seeds. Thus, dry mutant
seeds had less triacylglycerol content, while other neutral lipids like diacylglycerols were not affected. Furthermore, the
metabolic flow of the different glycerolipid species into seed oil in the developing seeds was reduced at different stages
of seed formation in the fata1 fata2 line. This diminished metabolic flow induced increases in the proportion of linolenic and erucic fatty acids in the seed
oil, in a similar way as previously reported for the wri1 Arabidopsis mutant that accumulates oil poorly. The similarities between these two mutants and the origin of their phenotype
are discussed in function of the results. |
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