Abstract

To compare the biosynthesis pathways of aromatic and isoprenoid cytokinins, a series of nucleoside derivatives of natural cytokinins was synthesized and their cytokinin activity was determined in a test system based on the model plant Arabidopsis thaliana. Cytokinin nucleosides are known to lack the hormonal activity until cleaving the ribose moiety at the position 9. Our experiments have shown that both ribo- and 5'-deoxyribo derivatives of N⁶-isopentenyladenine were able to turn into active cytokinins in planta exhibiting cytokinin activity. By contrast, 5'-deoxy nucleosides of aromatic cytokinins did not show similar activity. Since 5'-deoxy nucleosides cannot phosphorylate in vivo, the direct pathway of active cytokinin formation by cleavage of nucleotides is blocked here. The detected activity in 5'-deoxy nucleosides of isoprenoid cytokinins and the lack of the activity in 5'-deoxy nucleosides of aromatic cytokinins indicates the difference in the biosynthesis of these compounds.

中文翻译：

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异戊二烯和芳香细胞分裂素的生物合成比较分析。

摘要

为了比较芳香族和类异戊二烯细胞分裂素的生物合成途径，合成了一系列天然细胞分裂素的核苷衍生物，并在基于拟南芥模型植物的测试系统中确定了它们的细胞分裂素活性。已知细胞分裂素核苷在切割第9位的核糖部分之前缺乏激素活性。我们的实验表明，N ⁶的核糖和5'-脱氧核糖衍生物-异戊烯腺嘌呤能够在植物中转变为具有细胞分裂素活性的活性细胞分裂素。相比之下，芳香细胞分裂素的5'-脱氧核苷没有显示出相似的活性。由于5'-脱氧核苷无法在体内磷酸化，因此此处阻断了通过核苷酸切割形成活性细胞分裂素的直接途径。在类异戊二烯细胞分裂素的5'-脱氧核苷中检测到的活性以及在芳香族细胞分裂素的5'-脱氧核苷中缺乏活性表明这些化合物在生物合成上的差异。