Scientists at the University of Jena, Germany have put forth a novel
explanation of the evolutionary driving force behind a genetic switching
circuit that regulates flower development and survival. The hypothesis,
based around the obligatory pairing of certain molecules, is published
January 16 in the open-access journal PLoS Computational Biology.

The authors believe that their findings "strongly support the view that the
unexpected complexity of the floral homeotic gene switch considered here was
not simply produced by random genetic drift but evolved because it provided
the plant with a clear selective advantage"

In the Arabidopsis thaliana flower, a particular class of genes - DEF-like
and GLO-like floral homeotic genes - regulates the development of petals and
stamens over long periods of time, using "genetic switches". These genes are
self-activating via a heterodimer (a complex of two different molecules) of
their protein products, therefore binding the activity of each gene to that
of the other one. The reason for their total functional interdependence has
long remained unclear.

The authors used computational modeling to investigate potential
explanations for why these two interdependent genes exist, since one gene
alone could in principle provide the switching functionality in these
plants' organs. The group shows that the obligate heterodimerization
mechanism found in DEF- and GLO-like genes reduces the susceptibility of the
genetic switch to failure caused by stochastic noise or interference.

The study was targeted at a specific mechanism of genetic regulation and
cannot directly be transferred to other mechanisms, caution the authors.
However, the underlying methodology may be applicable to a whole range of
genetic regulatory motifs.

Link to the article: [dx.plos.org]

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