Cytokinin-Active Ribonucleosides in Phaseolus RNA. II. Distribution in tRNA Species from Etiolated P. vulgaris L. Seedlings

The distribution of cytokinin-active ribonucleosides in tRNA species from etiolated Phaseolus vulgaris L. seedlings has been 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 $\text{tRNA}^{\text{Cys}}$, 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 $\text{tRNA}^{\text{Ser}}$ species and with minor tRNALeu species. In addition, several anomalous peaks of cytokinin activity that could not be directly attributed to U group tRNA species were detected.