CYTOKININS FROM GROWTH-REGULATOR AUTONOMOUS CALLUS-TISSUE

Callus tissue of the monocotyledon, Haworthia mirabilis Haw., was cultured in the absence of exogenous plant growth regulators (cytokinin and auxin). The tissue was extracted with aqueous ethanol and the extract was purified by chromatography and tested with the tobacco callus cell division assay. Cytokinins with chromatographic properties corresponding to those of zeatin and zeatin riboside were detected. Transfer RNA was isolated from the autonomous tissue, hydrolyzed enzymatically and examined for cytokinin activity. Cytokinin-active ribonucleosides with chromatographic properties corresponding to those of zeatin riboside and N6-(Δ2-isopentenyl) adenosine were found. This is the first reported analysis of cytokinins from spontaneously autonomous callus from a monocotyledon. Exogenous growth regulators in the culture medium affect the content of free, ethanol-soluble cytokinins in the callus tissue. © 1979.