Differential Contribution of the First Two Enzymes of the MEP Pathway to the Supply of Metabolic Precursors for Carotenoid and Chlorophyll Biosynthesis in Carrot (Daucus carota)
Author
dc.contributor.author
Simpson Alfaro, Kevin
Author
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Quiroz Iturra, Luis
Author
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Rodríguez Concepción, Manuel
Author
dc.contributor.author
Stange Klein, Claudia
Admission date
dc.date.accessioned
2017-01-05T19:32:25Z
Available date
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2017-01-05T19:32:25Z
Publication date
dc.date.issued
2016
Cita de ítem
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Frontiers in Plant Science August 2016 Volume 7 Article 1344
es_ES
Identifier
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10.3389/fpls.2016.01344
Identifier
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https://repositorio.uchile.cl/handle/2250/142292
Abstract
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Carotenoids and chlorophylls are photosynthetic pigments synthesized in plastids from metabolic precursors provided by the methylerythritol 4-phosphate (MEP) pathway. The first two steps in the MEP pathway are catalyzed by the deoxyxylulose 5-phosphate synthase (DXS) and reductoisomerase (DXR) enzymes. While DXS has been recently shown to be the main flux-controlling step of the MEP pathway, both DXS and DXR enzymes have been proven to be able to promote an increase in MEP-derived products when overproduced in diverse plant systems. Carrot (Daucus carota) produces photosynthetic pigments (carotenoids and chlorophylls) in leaves and in light-exposed roots, whereas only carotenoids (mainly alpha- and beta-carotene) accumulate in the storage root in darkness. To evaluate whether DXS and DXR activities influence the production of carotenoids and chlorophylls in carrot leaves and roots, the corresponding Arabidopsis thallana genes were constitutively expressed in transgenic carrot plants. Our results suggest that DXS is limiting for the production of both carotenoids and chlorophylls in roots and leaves, whereas the regulatory role of DXR appeared to be minor. Interestingly, increased levels of DXS (but not of DXR) resulted in higher transcript abundance of endogenous carrot genes encoding phytoene synthase, the main rate-determining enzyme of the carotenoid pathway. These results support a central role for DXS on modulating the production of MEP-derived precursors to synthesize carotenoids and chlorophylls in carrot, confirming the pivotal relevance of this enzyme to engineer healthier, carotenoid-enriched products
es_ES
Patrocinador
dc.description.sponsorship
Chilean Regular Fondecyt 1130245
CSIC 11/12
Spanish Ministry of Economy and Competitiveness BIO2014-59092-P
Generalitat de Catalunya 2014SGR-1434
Severo Ochoa Programme for Centres of Excellence SEV-2015-0533
Differential Contribution of the First Two Enzymes of the MEP Pathway to the Supply of Metabolic Precursors for Carotenoid and Chlorophyll Biosynthesis in Carrot (Daucus carota)