Die bedeutung von cAMP und verschiedenen zuckern für die wirkung von phytohormonen auf das streckungswachstum von Avena-koleoptilzylindern

Abstract

Summary 1. The elongation growth of Avena coleoptile cylinders is influenced by different sugars (2,5⋅10−2M) in a different manner. Sucrose alone is clearly stimulating the elongation growth. Glucose and fructose, alone and in combination, have no effect. Given together with sucrose, glucose and fructose are diminishing the effect that sucrose alone would produce. 2. Abscisic acid (5⋅10−6M) inhibitis elongation growth of coleoptile segments. This effect is weakened by glucose and fructose in particular, but also sucrose, galactose and mannose. 3. Indole-3-acetic acid (10−5M) produces a strong stimulation of coleoptile cylinder growth, which is further increased by sucrose. Galactose counteracts this effect completely, mannose and glucose only diminish the IAA-effect. Fructose and the combination fructose/glucose have no influence. 4. Gibberellin A3 (10−4M) doesn't stimulate the growth. Together with glucose and fructose however, there is an evident effect on elongation growth. GA3 also increases the IAA-stimulation, but reduces the sucrose dependent growth. 5. All these GA3-effects can also be produced by cAMP (10−4M) and theophyllin (10−8M). 6. The indentity of cAMP and theophyllin-effects means, that there can't be a fundamental uptake barrier for cAMP. The corresponding of cAMP-, theophyllin- and GA3-effects seems to be an indication, that in this case cAMP is the second messenger for GA3. To understand the interaction between phytohormones and cAMP on one side, and the sugars on the other side, the following proposal is made: One of the elongation stimulating effects of IAA and GA3 is produced by inducing certain invertases and sugar permeases, and therefore by increasing the turgor in the cell.