On the occurrence of a high content of cytokinins in rice callus tissues

Abstract

Rice callus tissues contained at least three active cytokinin compounds: zeatin, its riboside and N6-(δ2-isopentenyl) adenosine. These butanol-extractable cytokinins were identified by their chromatographic mobilities in Sephadex LH-20, paper and gas chromatography. Zeatin, the apparent major cytokinin, was present at concentrations of 0.7 to 1.0 μg/g fresh tissue and 1.3 to 1.7 μg/g fresh tissue in 10−7 M and 10−55 M 2,4-D callus, respectively. On the basis of these and earlier results, the induction and growth of rice callus tissue is discussed in relation to the occurrence of cytokinins in the tissue.