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During the development of organisms, a particular event repeatedly occurs: a signal appears temporarily, but the processes it triggers must be maintained for example, when the fate of cells in the embryo is established. The plant hormone auxin plays an important role as a signalling molecule during embryo development of the thale cress (Arabidopsis thaliana), a model plant widely used in genetic studies. Researchers from the Max Planck Institute for Developmental Biology and the University of Tbingen were already familiar with important components, through which auxin exerts its influence, and some of their interactions. They have now combined several of these components in a regulatory network such that an increasing concentration of auxin can "switch on" genes for the embryo's normal development. Once a certain point has been reached, the genes do not halt their increased activity, or only do so gradually, even if the auxin concentration declines. Similar switching mechanisms are also known from the animal kingdom.
In the normal course of events, a plant embryo becomes a seedling and the seedling grows into a plant with all of its organs: roots, stem, leaves and flowers. The foundations for this development are laid during early embryonic development. The plant hormone auxin is an important signal transmitter during this phase of development. It was already known that it promotes, for example, the breakdown of an inhibitor that can prevent certain factors from activating their target genes. In an early phase of embryo development, the auxin concentration rises in the cells located at the top of the embryo, from which the above-ground parts of the plant will later form. Shortly after that, auxin is transported into the lower cells. So complicated, so good. However, this does not fully explain the exact r
|Contact: Gerd Juergens|