Metabolic profiling of transgenic tomato plants overexpressing hexokinase reveals that the influence of hexose phosphorylation diminishes during fruit development.
We have conducted a comprehensive metabolic profiling on tomato (Lycopersicon esculentum) leaf and developing fruit tissue using a recently established gas chromatography-mass spectrometry profiling protocol alongside conventional spectrophotometric and liquid chromatographic methodologies. Applying a combination of these techniques, we were able to identify in excess of 70 small-M(r) metabolites and to catalogue the metabolite composition of developing tomato fruit. In addition to comparing differences in metabolite content between source and sink tissues of the tomato plant and after the change in metabolite pool sizes through fruit development, we have assessed the influence of hexose phosphorylation through fruit development by analyzing transgenic plants constitutively overexpressing Arabidopsis hexokinase AtHXK1. Analysis of the total hexokinase activity in developing fruits revealed that both wild-type and transgenic fruits exhibit decreasing hexokinase activity with development but that the relative activity of the transgenic lines with respect to wild type increases with development. Conversely, both point-by-point and principal component analyses suggest that the metabolic phenotype of these lines becomes less distinct from wild type during development. In summary, the data presented in this paper demonstrate that the influence of hexose phosphorylation diminishes during fruit development and highlights the importance of greater temporal resolution of metabolism.
Roessner-Tunali
Ute
U
Department of Lothar Willmitzer, Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Golm, Germany.
Hegemann
Björn
B
Lytovchenko
Anna
A
Carrari
Fernando
F
Bruedigam
Claudia
C
Granot
David
D
Fernie
Alisdair R
AR
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002851:Chromatography, High Pressure Liquid; D005638:Fruit / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D008401:Gas Chromatography-Mass Spectrometry; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D006593:Hexokinase / Q000235:genetics / Q000378:metabolism*; D006601:Hexoses / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D010766:Phosphorylation; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D025341:Principal Component Analysis / Q000379:methods; D013053:Spectrophotometry
D029681:Arabidopsis Proteins; D006601:Hexoses; D006593:Hexokinase; C473630:ATHXK1 protein, Arabidopsis