Distinct Isoprenoid Origins of cis- and trans-Zeatin Biosyntheses in Arabidopsis

摘要: Plants produce the common isoprenoid precursors isopentenyl diphosphate and dimethylallyl (DMAPP) through methylerythritol phosphate (MEP) pathway in plastids mevalonate (MVA) cytosol. To assess which pathways contribute DMAPP for cytokinin biosynthesis, metabolites from each were selectively labeled with 13C Arabidopsis seedlings. Efficient labeling was achieved by blocking endogenous genetically or chemically during feed of a precursor specific to MEP MVA pathways. Liquid chromatography-mass spectrometry analysis demonstrated that prenyl group trans-zeatin (tZ) isopentenyladenine is mainly produced pathway. In comparison, large fraction cis-zeatin (cZ) derivatives provided When expressed as fusion proteins green fluorescent protein cells, four adenosine phosphate-isopentenyltransferases (AtIPT1, AtIPT3, AtIPT5, AtIPT8) found plastids, agreement idea primarily provides tZ isopentenyladenine. On other hand, AtIPT2, tRNA isopentenyltransferase, detected Because prenylated adenine moiety usually cZ type, formation seedlings might involve transfer tRNA. Distinct origins proportions biosynthesis suggest plants are able separately modulate level these species.