Biochemical and Cytological Analyses of RNA Synthesis in Kinetin-treated Pea Root Parenchyma

Excised cortical parenchyma from the pea root (cv. Little Marvel) responds to kinetin/auxin treatment with an increased rate of RNA synthesis well before reinitiating DNA synthesis. Few cells synthesize RNA in the 1st hour of culture. In the presence of kinetin/auxin, the nuclear labeling index increases 2.5-fold as compared to control cultures. The RNA synthesis response has an apparent lag period of 2-4 hours as shown by double label ([(3)H]adenosine/[(14)C]adenosine) experiments. Qualitatively, the RNA synthesized at 4-6 hours sediments between 18S and 5S. The RNA synthesized at 14-16 hours and 24-26 hours is primarily ribosomal RNA when kinetin is present. In the absence of kinetin, no clear pattern of RNA synthesis emerges.The data are interpreted to mean that kinetin treatment elicits RNA synthesis in a small proportion of the population initially and this may involve messenger-like RNA. Later, more cells synthesize RNA and this is primarily rRNA.