A mutant of the Arabidopsis thaliana TOC159 gene accumulates reduced levels of linolenic acid and monogalactosyldiacylglycerol
Copyright © 2013 Elsevier Masson SAS. All rights reserved.
| Veröffentlicht in: | Plant physiology and biochemistry : PPB. - 1991. - 73(2013) vom: 15. Dez., Seite 344-50 |
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| Weitere Verfasser: | , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2013
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| Zugriff auf das übergeordnete Werk: | Plant physiology and biochemistry : PPB |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't 16:3 18:3 Arabidopsis thaliana Fad Fad5 MGD1 synthase MGDG TOC mehr... |
| Zusammenfassung: | Copyright © 2013 Elsevier Masson SAS. All rights reserved. Previous studies have shown that a mutant of Arabidopsis that lacks the Toc159 receptor is impaired in chloroplast biogenesis. The mutant is referred as plastid protein import 2 or ppi2 and has an albino phenotype due to its inability to import the photosynthetic proteins. In this study, we measured fatty acid composition and transcript levels of plastid-localized fatty acid desaturases in the wild type and ppi2 mutant. The objective was to evaluate whether the Toc159 receptor was critical in the import of lipid-synthesizing enzymes. The ppi2 mutant accumulated decreased levels of oleic acid (18:1) and α-linolenic acid (18:3). The mutant accumulated drastically reduced amounts of the chloroplast lipid monogalactosyldiacylglycerol (MGDG), which contains more than 80% of 18:3. The expression of genes that encode stearoyl-ACP desaturase and MGD1 synthase were down-regulated in the ppi2 mutant, and this corresponded to decreased levels of 18:1 and MGDG, respectively. We conclude that in the ppi2 mutant the impaired synthesis of MGDG resulted in decreased amounts of 18:3. The mutant however, had a 30-fold increase in fad5 transcript levels; this increase was mirrored by a 16- to 50-fold accumulation of hexadecatrienoic acid (16:3), a fatty acid found exclusively in MGDG. Taken together, these data suggest that the Toc159 receptor is required in the import of stearoyl-ACP desaturase and MGD1 synthase into the chloroplasts. Since the expression of fad5 gene was up-regulated in the ppi2 mutant, we propose that fad5 desaturase is imported into plastids through the atToc132/atToc120 protein import pathway |
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| Beschreibung: | Date Completed 29.07.2014 Date Revised 30.09.2020 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1873-2690 |
| DOI: | 10.1016/j.plaphy.2013.10.018 |