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Free keywords:
Phaseolus lunatus
Leguminosae
Lima bean
Isoprenoid biosynthesis
Cross talk
1-deoxy-d-xylulose
Mevalonate
Terpenoids
Volatiles
Isotopically labeled
Inhibitors
Irms
Isotopic discrimination
Mevalonate-independent pathway
Isoprenoid biosynthesis
Arabidopsis-thaliana
Nonmevalonate pathway
Plastidial pathways
Higher-plants
Cross-talk
Units
1-deoxy-d-xylulose
Homoterpenes
Abstract:
Two independent pathways contribute in higher plants to the formation of isopentenyl diphosphate (IDP), the central building block of isoprenoids. In general, the cytosolic mevalonate pathway (MVA) provides the precursors for sesquiterpenes and sterols, whereas the plastidial methylerythritol pathway (MEP) furnishes the monoterpene-, diterpene- and carotenoids. Administration of deuterium labeled 1-deoxy-D-xylulose and mevalolactone to lima beans (Phaseolus lunatus), followed by gas chromatographic separation and mass spectro-metric analysis of de novo produced volatiles revealed that the strict separation of both pathways does not exist. This could be confirmed by blocking the pathways individually with cerivastatin (R) (MVA) and fosmidomycin (MEP), respectively. Isotopic ratio mass spectrometry (IRMS) at natural abundance levels demonstrated independently and without the need for labeled precursors a dynamic allocation of the MVA- or the MEP-pathway in the biosynthesis of the nerolidol-derived homoterpene 4,8-dimethyl-nona-1,3,7-triene (DMNT). Insect-feeding upregulated predominantly the MVA-pathway, while the fungal elicitor alamethicin stimulated the biosynthesis of DMNT via the MEP-pathway. (c) 2006 Elsevier Ltd. All rights reserved. [References: 40]
