Title: Responses to auxin signals: an operating principle for dynamical sensitivity yet high resilience

Speaker: Olivier Martin (GQE-Le Moulon, INRA, Université Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Gif-sur-Yvette, France)

Abstract: Plants depend on the signaling of the phytohormone auxin for their development and for responding
to environmental perturbations. The associated biomolecular signaling network involves a negative
feedback at the level of the Aux/IAA proteins which mediate the influence of auxin (the signal) on the
ARF transcription factors (the drivers of the response). To probe the role of this feedback, we consider
alternative in silico signaling networks implementing different operating principles. By a comparative
analysis, we find that the presence of a negative regulatory feedback loop allows the system to have
a far larger sensitivity in its dynamical response to auxin. At the same time, this sensitivity does not
prevent the system from being highly resilient. Given this insight, we reconsider previously published
models and build a new quantitative and calibrated biomolecular model of auxin signaling.