title: Cytokinin biosynthesis in cultured rootless tobacco plants.
abstract: Biosynthesis of cytokinin in shoots was examined by growing rootless tobacco (Nicotiana tabacum) plants in vitro. The rootless plants were originated by culturing tobacco callus on a high cytokinin-low auxin medium to induce the formation of plantlets which were then grown on medium without exogenous cytokinin and auxin. The rootless plants supplied with [(14)C]adenine synthesized ethanol-ethyl acetate-water-soluble radioactive components, portions of which had the same chromatographic and electrophoretic mobilities as N(6)-(Delta(2)-isopentenyl)adenine, N(6)-(Delta(2)-isopentenyl)adenosine, 6-(4-hydroxy-3-methyl-2-butenylamino)purine and 6-(4-hydroxy-3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine. The total amount of these four major cytokinins was estimated to be present at a concentration of 14 to 23 nanomoles per kilogram of rootless plant. These data indicate that adenine serves as a precursor of the purine moiety of cytokinin molecules and that the cytokinin biosynthetic sites are also located in the shoot in addition to the presumed root sites.
authors: Science Division, University of Wisconsin-Parkside, Kenosha, Wisconsin 53141.
authors: C M
authors: CM
authors: Chen
authors: B
authors: B
authors: Petschow