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| Author: | S.J. Wellensiek |
Abstract:
An attempt is made to synthesize the mechanisms of flower formation of all seed plants, based on literature and own experience, especially on the concept that "flower-forming genes" are periodically inactivated and activated.
Five partial processes in the "floral chain" are distinguished:
- In vegetative plants floral-hormone forming genes are inactivated by an immobile blocking, occurring in different gene-determined intensities.
Deblocking takes place by external factors, light, temperature, chemicals.
After deblocking, the specific floral-hormone forming DNA is activated and forms specific RNA. Neutral plants have no blocking.
- Floral hormone(s) is (are) formed via the specific RNA. Recent evidence (Bernier, 1976) shows that a floral hormone may consist of more than one component, that one of them may be a cytokinin, that in different plants different floral hormones or combinations of floral hormones may occur.
- Besides the immobile blocking or inhibition sub 1, mobile floral inhibitors may be formed by genic action.
In vegetative plants the inhibitor genes are active.
Floral-hormone deblocking factors may block the inhibitor genes, but already formed inhibitors remain active.
Abscisic acid may act as an inhibitor.
Flower formation results from a competition between floral hormone(s) and inhibitor(s).
- Floral hormones move upwards and downwards from leaves to apices through the phloem.
Their movement may be hampered by the mass flow of assimilates and perhaps by inhibitors.
- Flower formation results from an activation of floral genes in an apex ("evocation") by deblocking through floral hormone(s) and external factors.
A tentative scheme on the last page shows the mutual relationships of these partial processes.
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