article published yes Eva Benková author 38F4F166-F248-11E8-B48F-1D18A9856A870000-0002-8510-9739 Erwin Witters author Walter Van Dongen author Jan Kolář author Václav Motyka author Břetislav Brzobohatý author Henri Van Onckelen author Ivana Macháčková author 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 ofN 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. American Society of Plant Biologists1999 eng 0032-0889 1048268010.1104/pp.121.1.245 1211245 - 251 yes Benková, Eva, et al. “Cytokinins in Tobacco and Wheat Chloroplasts. Occurrence and Changes Due to Light/Dark Treatment.” <i>Plant Physiology</i>, vol. 121, no. 1, American Society of Plant Biologists, 1999, pp. 245–51, doi:<a href="https://doi.org/10.1104/pp.121.1.245">10.1104/pp.121.1.245</a>. Benková E, Witters E, Van Dongen W, Kolář J, Motyka V, Brzobohatý B, Van Onckelen H, Macháčková I. 1999. Cytokinins in tobacco and wheat chloroplasts. Occurrence and changes due to light/dark treatment. Plant Physiology. 121(1), 245–251. E. Benková, E. Witters, W. Van Dongen, J. Kolář, V. Motyka, B. Brzobohatý, H. Van Onckelen, I. Macháčková, Plant Physiology 121 (1999) 245–251. Benková, E., Witters, E., Van Dongen, W., Kolář, J., Motyka, V., Brzobohatý, B., … Macháčková, I. (1999). Cytokinins in tobacco and wheat chloroplasts. Occurrence and changes due to light/dark treatment. <i>Plant Physiology</i>. American Society of Plant Biologists. <a href="https://doi.org/10.1104/pp.121.1.245">https://doi.org/10.1104/pp.121.1.245</a> Benková, Eva, Erwin Witters, Walter Van Dongen, Jan Kolář, Václav Motyka, Břetislav Brzobohatý, Henri Van Onckelen, and Ivana Macháčková. “Cytokinins in Tobacco and Wheat Chloroplasts. Occurrence and Changes Due to Light/Dark Treatment.” <i>Plant Physiology</i>. American Society of Plant Biologists, 1999. <a href="https://doi.org/10.1104/pp.121.1.245">https://doi.org/10.1104/pp.121.1.245</a>. Benková E, Witters E, Van Dongen W, et al. Cytokinins in tobacco and wheat chloroplasts. Occurrence and changes due to light/dark treatment. <i>Plant Physiology</i>. 1999;121(1):245-251. doi:<a href="https://doi.org/10.1104/pp.121.1.245">10.1104/pp.121.1.245</a> E. Benková <i>et al.</i>, “Cytokinins in tobacco and wheat chloroplasts. Occurrence and changes due to light/dark treatment,” <i>Plant Physiology</i>, vol. 121, no. 1. American Society of Plant Biologists, pp. 245–251, 1999. 28652018-12-11T12:00:00Z2025-06-26T08:49:10Z