An alternative cytokinin biosynthesis pathway

• DOI: 10.1073/pnas.260504097
• Publication Date: 2002-07-26T14:36:44Z
• Authors: Crister Åstot; Karel Dolezal; Anders Nordström; Qun Wang; Tim Kunkel; Thomas Moritz; Nam-Hai Chua; Göran Sandberg
• Keywords: 0303 health sciences; 03 medical and health sciences; Alkyl and Aryl Transferases; Cytokinins; Terpenes; Isotope Labeling; Arabidopsis; Cytochromes; Gene Expression; Deuterium

Studies of de novo cytokinin biosynthesis in isopentenyltransferase (ipt)-transformed Arabidopsis thaliana, involving vivo deuterium labeling and mass spectrometry, showed that the biosynthetic rate zeatinriboside-5'-monophosphate was around 66-fold higher than isopentenyladenosine-5'-monophosphate (iPMP), proposed primary product Agrobacterium ipt. Double tracer analysis, using [(2)H(6)] isopentenyladenosine oxide, provided evidence for an alternative, iPMP-independent, pathway zeatin-type cytokinins, present both ipt-expressing wild-type thaliana. Reduction flux alternative by use mevastatin, inhibitor 3-hydroxy-3-methylglutaryl CoA reductase, indicated a terpenoid origin side-chain precursor iPMP independent pathway.