An alternative cytokinin biosynthesis pathway.
Studies of de novo cytokinin biosynthesis in isopentenyltransferase (ipt)-transformed Arabidopsis thaliana, involving in vivo deuterium labeling and mass spectrometry, showed that the biosynthetic rate of zeatinriboside-5'-monophosphate was around 66-fold higher than that of isopentenyladenosine-5'-monophosphate (iPMP), the proposed primary product of the Agrobacterium ipt. Double tracer analysis, using [(2)H(6)] isopentenyladenosine and deuterium oxide, provided evidence for an alternative, iPMP-independent, biosynthetic pathway for zeatin-type cytokinins, present in both ipt-expressing and wild-type Arabidopsis thaliana. Reduction of the biosynthetic flux in the alternative pathway by use of mevastatin, an inhibitor for 3-hydroxy-3-methylglutaryl CoA reductase, indicated a terpenoid origin for the side-chain precursor of the iPMP independent pathway.
Astot
C
C
Umeâ Plant Science Center, Department of Forest Genetics and Plant Physiology, The Swedish University of Agricultural Sciences, S-901083 Umeâ, Sweden.
Dolezal
K
K
Nordström
A
A
Wang
Q
Q
Kunkel
T
T
Moritz
T
T
Chua
N H
NH
Sandberg
G
G
D019883:Alkyl and Aryl Transferases / Q000235:genetics; D017360:Arabidopsis; D003580:Cytochromes; D003583:Cytokinins / Q000096:biosynthesis*; D003903:Deuterium; D015870:Gene Expression; D007553:Isotope Labeling; D013729:Terpenes
D003580:Cytochromes; D003583:Cytokinins; D013729:Terpenes; D003903:Deuterium; D019883:Alkyl and Aryl Transferases; C024274:adenylate isopentenyltransferase