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 tRNA(Cys), tRNA(Trp), tRNA(Tyr), a major peak of tRNA(Phe), and a large fraction of tRNA(Leu) were devoid of cytokinin activity in the tobacco bioassay. Cytokinin activity was associated with all fractions containing tRNA(Ser) species and with minor tRNA(Leu) species. In addition, several anomalous peaks of cytokinin activity that could not be directly attributed to U group tRNA species were detected.