Einfluß von Auxin und Cytokinin auf die RNA-Synthese in sterilem Tabakgewebe

Summary

The influence of auxin and cytokinin on RNA synthesis was investigated by measuring ³²PO₄ ³⁻-incorporation into polysomes and polysomal RNAs of tissue grown from pith of Nicotiana tabacum L. The test tissue grown on a medium containing a minimum of auxin and cytokinin was further starved for a period of 12 h prior to the experiments. The tests were carried out under the following different conditions: 1. without any growth substances, 2. with auxin only, 3. with kinetin only, and 4. with auxin and kinetin. The tissues were incubated in small volumes of the test medium for 1–8 h on a shaker. The last hour of incubation was carried out in the presence of ³²PO₄ ³⁻.

Differences in ³²PO₄ ³⁻ uptake into the polysomes were observed as early as after 3 h of incubation. Kinetin alone shows no effect at all, auxin causes increased synthesis of polysomal RNAs, and kinetin administered together with auxin augments the increase of ³²PO₄ ³⁻ uptake into polysomes and polysomal RNAs observed with auxin alone. These results and those of Seth and Wareing [J. exp. Bot. 18, 65–77 (1967)], Bhattacharyya and Roy [Biochem. biophys. Res. Commun. 35, 606–610 (1969)], and Venis [Proc. nat. Acad. Sci. (Wash.) 68, 1824–1827 (1971)] lead to the following working hypothesis: while auxins exert their influence on the RNA transcription, cytokinins may possibly influence the translation process.