Evidence of cytokinin bases, ribosides and glucosides in roots of Douglas-fir, Pseudotsuga menziesii

Abstract

Concentrations of cytokinin-like compounds were measured in root tips of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) collected in spring. Cytokinin bases and ribosides were estimated by radioimmunoassay after purification by immunoaffinity (zeatin riboside and isopentenyladenosine antibodies coupled to cellulose gel) and high performance liquid chromatography. Cytokinin glucosides were similarly analyzed in root extracts treated with beta-glucosidase and octadecyl-silica column chromatography in conjunction with immunoaffinity purification. The identity of predominant cytokinins obtained after enzymatic degradation was confirmed by gas chromatography-mass spectrometry. Each of the observed cytokinin bases and ribosides seemed to have a corresponding hexose conjugate form. Total quantity of cytokinin glucosides was twice that of cytokinin bases and ribosides, and the major compound was isopentenyladenosine hexose conjugate.