Isolation and Estimation of Cytokinins and Cytokinin-Containing Transfer RNAs from Cucumis sativus L. var. Guntur Seedlings

N(6)-(Delta(2)-Isopentenyl) adenosine antibodies were used for the isolation of free cytokinins and cytokinin-containing tRNAs from parts of Cucumis sativus L. var. Guntur seedlings and for the estimation of cytokinins in them. Immobilized N(6)-(Delta(2)-isopentenyl) adenosine antibodies retained tRNAs containing N(6)-(Delta(2)-isopentenyl) adenosine and N(6)-(4-hydroxy-3-methylbut-2-enyl) adenosine with equal efficiencies. There were at least five cytokinins in the free form in cucumber seedlings. N(6)-(4-Hydroxy-3-methylbut-2-enyl) adenosine, N(6)-(Delta(2)-isopentenyl) adenosine, and N(6)-(Delta(2)-isopentenyl) adenine were present at least to the extent of 80, 23, and 9 nanograms, respectively, in the cotyledons and 40, 6, and 3 nanograms, respectively, in the decotyledonated seedlings per gram of tissue. Only two cytokinins were found in the tRNAs of cucumber cotyledons, namely N(6)-(Delta(2)-isopentenyl) adenosine and N(6)-(4-hydroxy-3-methylbut-2-enyl) adenosine in amounts of 12 and 318 nanograms, respectively, per gram of tissue. Immunoaffinity chromatographic analysis of radiolabeled aminoacyl tRNAs from cucumber cotyledons showed that tRNA(Phe) and tRNA(Tyr) contained cytokinins whereas tRNA(Ala) did not.