Cytokinin-Active Ribonucleosides in Phaseolus RNA

Abstract

The distribution of cytokinin-active ribonucleosides in tRNA species from etiolated P. vulgaris L. seedlings was examined. Phaseolus tRNA was fractionated by benzoylated diethylaminoethyl-cellulose and RPC-5 chromatography and the distribution of cytokinin activity was compared with the distribution of tRNA species expected to correspond to codons beginning with U. Phaseolus tRNACys, tRNATrp, tRNATyr, a major peak of tRNAPhe and a large fraction of tRNALeu were devoid of cytokinin activity in the tobacco bioassay. Cytokinin activity was associated with all fractions containing tRNASer species and with minor tRNALeu species. Several anomalous peaks of cytokinin activity that could not be directly attributed to U group tRNA species were detected.