An Agar-diffusion Technique Applied to the Study of Gibberellins in Tomato (Lycopersicon esculentumMill.) Plants

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Abstract
Chromatography of extracts of agar blocks on which shoot tips of tomato had stood for 24 h revealed the presence of at least two gibberellin-like substances. Gibberellin-like activity detected by the dwarf pea bioassay was shown to be associated with activity in promoting elongation growth in tomato seedlings. The active substances were acidic; tests for the presence of ‘neutral’, ‘basic’ and ‘bound’ gibberellins in extracts of the agar blocks gave negative results. Amounts of gibberellin-like substances obtained from the shoot tips were increased by the incorporation of EDTA into the agar blocks but were apparently unaffected by the temperature (within the range 5–25 °C) at which the diffusion was carried out. It is suggested that the technique measured levels of diffusible gibberellins in the tissues at the time of their excision rather than rates of gibberellin synthesis during the diffusion period.