Kinetin inhibition of h-uracil and C-leucine incorporation by tobacco cells in suspension culture.

The rate of (14)C-leucine and (3)H-uracil incorporation by tobacco cells (Nicotiana tabaccum var. Samsun N.N.) in suspension culture was simultaneously decreased by the addition of kinetin at concentrations above 2.5 x 10(-5)m. Ribosomal RNA was the first RNA species affected by kinetin. The purine derivatives, adenine and N(6)-methyl-aminopurine, which exhibit low cytokinin activity overcame the inhibitory effects of kinetin. However, purine derivatives without cytokinin activity, guanine, N(6,6)-dimethyl-aminopurine, and 2-aminopurine, did not relieve kinetin inhibition.