Journal ArticleDOI
Cytokinin‐Inhibitor Antagonism in the Hormonal Control of α‐Amylase Synthesis and Growth in Barley Seed
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The effect of cytokinins and gibberellic acid on the inhibition of growth and α-amylase synthesis by germination inhibitors was investigated in intact and embryoless seed halves and an antagonism between cytokinin and germination inhibitor was also shown in root growth.Abstract:
The effect of cytokinins and gibberellic acid on the inhibition of growth and α-amylase synthesis by germination inhibitors was investigated in intact and embryoless seed halves. The cytokinins, kinetin and benzyladenine, effectively reversed the inhibition of coleoptile growth and α-amylase synthesis by abscisic acid and courmarin in barley seed. An antagonism between cytokinins, kinetin and benzyladenine, effectively reversed the inhibition of coleoptile growth and α-amylase synthesis by abscisic acid and coumarins in barley seed. An antagonism between cytokinins and germination inhibitors was also shown in root growth. Abscisic acid inhibited coleoptile growth to a greater extent than the root growth while the opposite held true in the case of coumarin.
The apparent increase in coleoptile growth and α-amylase synthesis by gibberellic acid plus abscisic acid (or coumarins) over abscisic acid (or coumarin) appears to be a result of the overall stimulation of growth and metabolism by exogenous gibberellic acid and probably does not involve an interaction of gibberellic acid with the inhibitors. Gibberellic acid reversed root inhibition to some extent.
Abscisic acid inhibition of gibberellic acid induced α-amylase synthesis in the embryoless endosperm was not reversed by excess gibberellic acid or kinetin Cytokinin reversal of inhibition of growth and enzyme synthesis probably depends on some factor(s) in the embryo. Cytokinin reversal of inhibitor action leading to enzymen synthesis and growth may be at the level of genome or at the site protein assembly.read more
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Journal ArticleDOI
Primary, preventive and permissive roles of hormones in plant systems
TL;DR: It is explained for the first time that seed dormancy can occur not only in presence of inhibitors as was generally believed but in many cases in absence or presence of promotors such as gibberellins or cytokinins.
Journal ArticleDOI
Cytokinin antagonists: Synthesis and physiological effects of 7-Substituted 3-Methylpyrazolo[4,3-d]Pyrimidines☆
TL;DR: A series of sixteen pyrazolo[4,3- d ]pyrimidine derivatives has been synthesized and tested for cytokinin antagonist activity in the tobacco bioassay.
Journal ArticleDOI
Post‐pollination phenomena in orchid flowers
TL;DR: The effects of ABA and its interactions with GA3, kinetin or NAA are explained in terms of the roles these hormones may play in synthesis of nucleic acids and enzymes.
Journal ArticleDOI
The rôle of abscisic acid in root growth and gravireaction: A critical review
P. E. Pilet,Peter W. Barlow +1 more
TL;DR: The evidence here also suggests that ABA is an inhibitory regulator of root growth, and appears to be involved in the differential growth that arises in response to a gravitational stimulus.
References
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Journal ArticleDOI
Effect of Kinetin on Protein & Nucleic Acid Metabolism in Xanthium Leaves During Senescence.
TL;DR: During the last 4 years, several chemical substances have been shown to retard senescence of leaf blades, and in this respect the compounds would atppear to substitute either directly or indirectly for the unknown so-called root factors.
Journal ArticleDOI
Gibberellic Acid Controlled Synthesis of α-Amylase in Barley Endosperm
TL;DR: Because the endosperm half of a barley seed produces several hydrolytic enzymes in response to added gibberellins, it is an attractive experimental system for a study of the mechanism of action of gibBerellic acid.
Journal ArticleDOI
Hormonal Control of Enzyme Synthesis: On the Mode of Action of Gibberellic Acid and Abscisin in Aleurone Layers of Barley
TL;DR: Data are consistent with the hypothesis that the expression of the GA effect requires the synthesis of enzyme-specific RNA molecules, and the similarity in the kinetics of inhibition between abscisin and 8-azaguanine or 6-methylpurine on the other suggests that abscillin may exert its action by inhibiting the synthesisOf these enzyme- specific RNA molecules or by preventing their incorporation into an active enzyme-synthesising unit.
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