Fleeting hormone cues get stabilized for plant organogenesis

Mol Syst Biol. 7: 507Unlike animals, plants continue to develop their body plan postembryonically and add organs such as leaves or flowers throughout their life. In the shoot apex, a central group of stem cells continuously proliferates and displaces older cells to the periphery, where they differentiate and new organs are initiated. It is known that local maxima of the plant hormone auxin coincide with the sites of new organs (Benkova et al , 2003) and there is good evidence that the local accumulation of auxin acts as a trigger for organogenesis (Dubrovsky et al , 2008). Extensive studies during the last decade revealed that these local auxin maxima are the result of a coordinated and highly dynamic directional cell‐to‐cell transport of auxin by specialized transport proteins (Petrasek et al , 2006). However, it is poorly understood how these rather dynamic changes in auxin concentration are translated into stable developmental decisions. In a recent article published in Molecular Systems Biology , Vernoux et al (2011) undertake the herculean task of comprehensively analyzing the vast auxin signaling network with over 50 interacting players and come to some surprisingly simple conclusions regarding how auxin signaling is fine tuned to allow for robust patterning in the shoot apex.The basic building blocks of the auxin signaling network are few: auxin response factors (ARFs) bind a conserved …