Manipulation of phytoene levels in tomato fruit: effects on isoprenoids, plastids, and intermediary metabolism

Fraser, Paul D, Enfissi, Genny, Halket, John M, Truesdale, Mark R, Yu, Dongmei, Gerrish, Christopher and Bramley, Peter M

(2007)

Fraser, Paul D, Enfissi, Genny, Halket, John M, Truesdale, Mark R, Yu, Dongmei, Gerrish, Christopher and Bramley, Peter M (2007) Manipulation of phytoene levels in tomato fruit: effects on isoprenoids, plastids, and intermediary metabolism. Plant Cell, 19 (10).

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Abstract

In tomato (Solanum lycopersicum), phytoene synthase-1 (PSY-1) is the key biosynthetic enzyme responsible for the synthesis of fruit carotenoids. To further our understanding of carotenoid formation in tomato fruit, we characterized the effect of constitutive expression of an additional tomato Psy-1 gene product. A quantitative data set defining levels of carotenoid/isoprenoid gene expression, enzyme activities, and metabolites was generated from fruit that showed the greatest perturbation in carotenoid content. Transcriptional upregulation, resulting in increased enzyme activities and metabolites, occurred only in the case of Psy-1, Psy-2, and lycopene cyclase B. For reactions involving 1-deoxy-d-xylulose5-phosphate synthase, geranylgeranyl diphosphate synthase, phytoene desaturase, zeta-carotene desaturase, carotene isomerase, and lycopene beta-cyclase, there were no correlations between gene expression, enzyme activities, and metabolites. Perturbations in carotenoid composition were associated with changes in plastid type and with chromoplast-like structures arising prematurely during fruit development. The levels of >120 known metabolites were determined. Comparison with the wild type illustrated that key metabolites (sucrose, glucose/fructose, and Glu) and sectors of intermediary metabolism (e.g., tricarboxylic [corrected] acid cycle intermediates and fatty acids) in the Psy-1 transgenic mature green fruit resembled changes in metabolism associated with fruit ripening. General fruit developmental and ripening properties, such as ethylene production and fruit firmness, were unaffected. Therefore, it appears that the changes to pigmentation, plastid type, and metabolism associated with Psy-1 overexpression are not connected with the ripening process.

Information about this Version

This is a Submitted version
This version's date is: 2007
This item is not peer reviewed

Link to this Version

https://repository.royalholloway.ac.uk/items/bc5517c9-c896-1201-62c0-ac0417be3951/5/

Item TypeJournal Article
TitleManipulation of phytoene levels in tomato fruit: effects on isoprenoids, plastids, and intermediary metabolism
AuthorsFraser, Paul D
Enfissi, Genny
Halket, John M
Truesdale, Mark R
Yu, Dongmei
Gerrish, Christopher
Bramley, Peter M
Uncontrolled KeywordsAlkyl and Aryl Transferases, Carotenoids, Fruit, Gas Chromatography-Mass Spectrometry, Gene Expression Regulation, Plant, Germination, Intramolecular Lyases, Lycopersicon esculentum, Models, Biological, Plant Proteins, Plants, Genetically Modified, Plastids, Polymerase Chain Reaction, Seeds, beta Carotene
DepartmentsFaculty of Science\Biological Science

Identifiers

doihttp://dx.doi.org/10.1105/tpc.106.049817

Deposited by Research Information System (atira) on 03-Jul-2014 in Royal Holloway Research Online.Last modified on 03-Jul-2014


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