Science Division, University of Wisconsin-Parkside, Kenosha, Wisconsin 53141.
Plant Physiol. 1978 Dec;62(6):861-5. doi: 10.1104/pp.62.6.861.
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.
通过在体外培养无根烟草（Nicotiana tabacum）植物，研究了芽中细胞分裂素的生物合成。无根植物是通过在高细胞分裂素-低生长素培养基上培养烟草愈伤组织而产生的，以诱导形成小植株，然后在不含外源细胞分裂素和生长素的培养基上生长。用 [(14)C] 腺嘌呤供给无根植物合成乙醇-乙酸乙酯-水溶性放射性成分，其中一部分与 N(6)-(Δ(2)-异戊烯基)腺嘌呤、N(6)-(Δ(2)-异戊烯基)腺苷、6-(4-羟基-3-甲基-2-丁烯基氨基)嘌呤和 6-(4-羟基-3-甲基-2-丁烯基氨基)-9-β-d-呋喃核糖基嘌呤具有相同的色谱和电泳迁移率。这四种主要细胞分裂素的总量估计存在于每千克无根植物 14 至 23 纳摩尔的浓度。这些数据表明，腺嘌呤是细胞分裂素分子嘌呤部分的前体，除了假定的根部位置外，细胞分裂素生物合成部位也位于芽中。
