ABSCISSION: ROLE OF RNA SYNTHESIS

Ethylene stimulated the incorporation of p32 into ribonucleic acid (RNA) in the abscission zone of bean explants (Phaseolus vulgaris L. var. Red Kidney). The enhancement was observed in all four peaks (soluble RNA, deoxyribonucleic acid, ribosomal RNA, and messenger RNA) separated by methylated albumin kieselguhr column chromatography, although 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 the ribosomal and messenger RNA. Actinomycin D, which blocks ethylene-stimulated abscission, inhibited p32 incorporation into all column fractions. 5-Fluorouracil, which blocked 50% of the ethylene-enhanced p32 incorporation, did not inhibit ethylene-enhanced abscission. The results indicate that ethylene may regulate abscission through control of specific RNA.