ABSTRACT
Cytokinins are a group of phytohormones that regulates cell division and differentiation in certain plant tissue cultures. A number of free, natural cytokinins have been efficiently purified by high performance liquid chromatography (HPLC) and identified unequivocally by mass spectrometry (MS). Plant tissues are known to contain certain nonspecific phosphatases which hydrolyze cytokinin nucleotides to their corresponding nucleosides. These enzymes are not completely inactivated during the usual extraction method of plant growth substances by the homogenation of plant tissues in ice-cold 80% methanol or ethanol. As cytokinins are present in most plant tissues and some microorganisms in very small amounts the isolation of a cytokinin of sufficient purity for characterization has required extensive use of chromatographic methods such as paper (PC), thin layer (TLC), gas (GC), and HPLC. Cytokinin glucosides have been identified as the dominant metabolites of cytokinins when fed to a number of plant tissues.
