Abscission: the role of RNA synthesis

Ethylene stimulated the incorporation of ³²P into RNA in the abscission zone of bean explants (Phaseolus vulgaris L. var. Red Kidney). The enhancement was observed in all fractions separated by methylated albumin kieselguhr column chromatography, although the magnitude of the increase was not the same for each fraction. Differential extraction of the nucleic acids indicated that the ethylene stimulation was confined to the fraction extracted with sodium lauryl sulfate, with the increase mainly in Fraction III (Ribosomal RNA) and Fraction IV (Messenger RNA). Actinomycin D, which blocks ethylene-stimulated abscission, inhibited ³²P incorporation into all column fractions. 5-Fluorouracil, which blocked 50% of the ethylene-enhanced ³²P incorporation, did not inhibit ethylene-enhanced abscission. The results indicate that ethylene may regulate abscission through control of specific RNA's.