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Metabolic flux analysis of plastidic isoprenoid biosynthesis in poplar leaves emitting and non-emitting isoprene.
Plant Physiol. 165, 37-51 (2014)
Publ. Version/Full Text
DOI
PMC
The plastidic 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway is one of the most important pathways in plants and produces a large variety of essential isoprenoids. Its regulation, however, is still not well understood. Using stable isotope 13C-labeling technique, we analyzed the carbon (C) fluxes through the MEP-pathway and into the major plastidic isoprenoid products in isoprene-emitting (IE) and transgenic isoprene non-emitting (NE) grey poplar (Populus x canescens). We assessed the dependence on temperature, light intensity and atmospheric [CO2]. Isoprene biosynthesis was by far (99%) the main C-sink of MEP-pathway intermediates in mature poplar leaves, and its production required several-fold higher C-fluxes compared to NE leaves with almost zero isoprene emission. To compensate for the much lower demand for C, NE leaves drastically reduced the overall C-flux within the MEP-pathway. Feedback inhibition of 1-deoxy-D-xylulose-5-phosphate synthase (DXS) activity by accumulated plastidic dimethylallyl diphosphate (DMADP) almost completely explained this reduction in C-flux. Our data demonstrate that short-term biochemical feedback regulation of DXS activity by plastidic DMADP is an important regulatory mechanism of the MEP-pathway. Despite being relieved from the large C demand of isoprene biosynthesis, NE plants redirected only approximately 0.5% of this 'saved' C towards essential non-volatile isoprenoids, i.e. β-carotene and lutein, most probably to compensate for the absence of isoprene and its antioxidant properties.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
1-deoxy-d-xylulose 5-phosphate Synthase; Methylerythritol 4-phosphate Pathway; Atmospheric Co2 Concentration; Isopentenyl Diphosphate; Hybrid Aspen; In-vivo; Carotenoid Biosynthesis; Phosphate Pathways; Quercus-robur; Cross-talk
ISSN (print) / ISBN
0032-0889
e-ISSN
1532-2548
Journal
Plant Physiology
Quellenangaben
Volume: 165,
Issue: 1,
Pages: 37-51
Publisher
American Society of Plant Biologists (ASPB)
Publishing Place
Rockville
Non-patent literature
Publications
Reviewing status
Peer reviewed