GIBBERELLINS AND CYTOKININS FROM EXCISED SHOOTS OF CHRYSANTHEMUM-MORIFOLIUM RAMAT - USING AGAR DIFFUSION AND TISSUE EXTRACTION METHODS

Young axillary shoots of C. morifolium Ramat. cv. Bright Golden Anne with developing influorescences were excised and inserted into a solid agar medium (1.5%, containing 2% sucrose and 0.01 M phosphate buffer) in a Fisons Growth Cabinet (20.degree. C and short photoperiods), to allow GA and cytokinins to diffuse into the agar. Acidic ethyl acetate-soluble (AES) and water-soluble (WS) GA were detected in purified extracts of shoots and agar by means of the lettuce hypocotyl bioassay and, when amounts were calculated in terms of GA3 equivalents, there was evidence that GA were produced during the diffusion periods. The total GA content of the shoots harvested at the end of the 3 successive 24 h periods of diffusion plus that in the agar itself was 8.4 and 3.7 times as great as that found in samples of shoots taken initially. The term produced is preferred to synthesized because of the possibility that interconversion of AES and WS GA might have occurred in the shoots. There was no indication that butanol-soluble cytokinins, as quantified by the soyabean callus bioassay in terms of zeatin equivalents, were synthesized or produced in Chrysanthemum shoots since, although small quantities of cytokinins were detected in the agar, a greater amount of these phytohormones was lost from the shoots during diffusion.