Genetic control of flower morphogenesis in Arabidopsis thaliana: a logicalanalysis

Motivation: A large number of molecular mechanisms at the basis of gene reg ulation have been described during the last few decades, it is now becoming possible to address questions dealing with both the structure and the dyna mics of genetic regulator?: networks, at least in the case of some of the b est-characterized organisms. Most recent attempts to address these question s deal with microbial or animal model systems. In contrast, we analyze here a gene network involved in the control of the morphogenesis of flowers in a model plant, Arabidopsis thaliana, Results: The genetic control of flower morphogenesis ill Arabidopsis involv es a large number of genes, of which 10 are considered here. The network to pology has been derived from published genetic and molecular data, mainly r elying on mRNA expression patterns under wild-type and mutant backgrounds, Using a 'generalized logical formalism', bile provide a qualitative model a nn derive the parameter constraints accounting for the different patterns o f gene expression found in the four floral organs of Arabidopsis (sepals, p etals, stamens and carpels), pins a 'non-floral' state. This model also all ows the simulation or the prediction of various mutant phenotypes. On the b asis of our model analysis; we predict rite existence of a sixth stable pat tern of gene expression, yet to be characterized experimentally Moreover; p ur dynamical analysis leads to the prediction of at least orae more regulat or of the gene LFY, likely to be involved in the transition from the non-fl owering state to the flowering pathways. Finally, this work, together with other theoretical and experimental considerations, leads us to propose some general conclusions about the structure of gene networks controlling devel opment. Contact: lams@servidor.unam.mx; denis@dbm.ulb.ac.be; abuylla@servidor:unam. mx