Further Stuides of Hormone-Regulated Senescence in Rumex Leaf Tissue
Senescence of leaf tissue and attached leaves can be inhibited by all of the three major groups of higher plant growth hormones. Leaf senescence can also be promoted by ethylene and abscisic acid. Which hormones are active in a given case seems to be primarily determined by the species used, although some evidence indicates this may be an oversimplification (e.g. Aspinall, et al., 1967; Goldthwaite and Laetsch, 1968). Previous work (Whyte and Luckwill, 1966; Goldthwaite and Laetsch, 1968) showed that net breakdown of chlorophyll and protein in excised leaf tissue of Rumex spp., is strongly inhibited by very low concentrations of gibberellic acid (GA3). Also described were several aspects of the behavior of the Rumex system including time courses of chlorophyll and protein loss, reversibility of the GA3 effect and activity of the cytokinin 6-benzylaminopurine (BAP). This report describes experiments carried out to further our understanding of hormone-controlled senescence in this plant. Included are studies of the effect of GA3 and BAP on senescence induced in attached leaves and the effect of other growth-regulators and combined applications of GA3 and cytokinins to excised leaf discs.
KeywordsChlorophyll Respiration Adenosine Photosynthesis Diethyl
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