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GrainGenes Reference Report: PPS-121-245

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Reference	PPS-121-245
Title	Cytokinins in tobacco and wheat chloroplasts. Occurrence and change due to light/dark treatment
Journal	Plant Physiology
Year	1999
Volume	121
Pages	245-251
Author	Benkova E [ Show all 8 ]
Abstract	Although cytokinins (CKs) affect a number of processes connected with chloroplasts, it has never been rigorously proven that chloroplasts contain CKs We isolated intact chloroplasts from tobacco (Nicotiana tabacum L cv SR1) and wheat (Triticum aestivum L cv Ritmo) leaves and determined their CKs by liquid chromatography/tandem mass spectroscopy Chloroplasts from both species contained a whole spectrum of CKs, including free bases (zeatin and isopentenyladenine), ribosides (zeatin riboside, and isopentenyladenosine), ribotides (isopentenyladenosine-5'-monophosphate, zeatin riboside-5'-monophosphate, and dihydrozeatin riboside-5'-monophosphate), and N-glucosides (zeatin-N(9)-glucoside, dihydrozeatin-N(9)-glucoside, zeatin-N(7)-glucoside, and isopentenyladenine-N-glucosides) In chloroplasts there was a moderately higher relative amount of bases, ribosides, and ribotides than in leaves, and a significantly increased level of N(9)-glucosides of zeatin and dihydrozeatin Tobacco and wheat chloroplasts were prepared from leaves at the end of either a dark or light period After a dark period, chloroplasts accumulated more CKs than after a light period. The differences were moderate for free bases and ribosides, but highly significant for glucosides. Tobacco chloroplasts from dark-treated leaves contained zeatin riboside-O-glucoside and dihydrozeatin riboside-O-glucoside, as well as a relatively high CK oxidase activity. These data show that chloroplasts contain a whole spectrum of CKs and the enzymatic activity necessary for their metabolism.
Keyword	[ Hide all but 1 of 13 ] chemical composition chloroplasts cytokinin dark enzyme activity leaves light metabolism nicotiana tabacum oxidoreductases photoperiod quantitative-analysis triticum aestivum

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