GIBBERELLIN, AS A REGULATOR OF PROTEIN AND RIBONUCLEIC ACID SYNTHESIS DURING SENESCENCE IN LEAF CELLS OF TARAXACUM OFFICINALE

Abstract

The addition of gibberellin A 3 (GA) to leaf discs of Taraxacum officinale Weber retards their senescence and delays the decline in the levels of chlorophyll, protein, and RNA. Incorporation of 14 C leucine and 14 C adenine into protein and RNA respectively was increased by GA. This enhancement of protein and RNA synthesis did not occur if the discs were supplied with actinomycin D before treatment with gibberellin. If, however, actinomycin D was added after the gibberellin treatment then the stimulatory effect of the hormone was maintained. These results suggest that the retarding action of gibberellins on leaf senescence could be mediated through a regulation of RNA synthesis that is DNA dependent.