Abstract
The effect of kinetin on changes in the RNA-content and the rate of incorporation of 32P into RNA during the senescence in detached leaves of Italian ryegrass (4X) were examined. Homogenates of leaves were centrifuged at 2, 000 g. The 4 or 6 fractions of RNA were obtained from the supernatant and precipitate by means of phenol method. The RNA of phenol-phase which was extracted from precipitate (nucleus, chloroplast) showed a high specific activity and this fraction was remarkably influenced by kinetin treatment. In the two experiments which were made with two different concentrations of kinetin, the 9 ppm kinetin maintained the sythesis and suppressed the breakdown of RNA of phenol-phase wich was extrated from nucleus and chloroplast fraction. On the other hands, 25 ppm kinetin inhibited slightly the synthesis and suppressed the breakdown of this fraction largely, Accordingly, it was suggested that kinetin might preserve the integrity of the RNA apparatus by maintaining synthesis and suppressing destruction of rapidly-rabeled RNA (messenger RNA) of nucleus and chloroplast, and thus the protein level is maintained successively, which is essential for the survival of the detached leaf.
