Integral control during gravitropism through the interplay of hormonal signaling and gene regulation

The interplay between hormone signaling and gene regulatory networks is instrumental in promoting the development of living organisms. In particular, plants have evolved mechanisms to sense gravity and orient themselves accordingly. Here, we present a mathematical model that reproduces plant gravitropic responses based on known molecular genetic interactions for auxin signaling coupled with a physical description of plant reorientation. The model allows one to analyze the spatiotemporal dynamics of the system, triggered by an auxin gradient that induces differential growth of the plant with respect to the gravity vector. Our model predicts two important features with strong biological implications: 1), robustness of the regulatory circuit as a consequence of integral control; and 2), a higher degree of plasticity generated by the molecular interplay between two classes of hormones. Our model also predicts the ability of gibberellins to modulate the tropic response and supports the integration of the hormonal role at the level of gene regulationThis work was supported by the Spanish Ministry of Science and Innovation (grant BIO2007-60923 to M.A.B.) and grants from Actions Thematiques Incitatives de Genopole and the Fondation pour la Recherche Medicale to A.J. G.R. was supported by a fellowship from the Generalitat Valenciana.Rodrigo Tarrega, G.; Jaramillo, A.; Blazquez Rodriguez, MA. (2011). Integral control during gravitropism through the interplay of hormonal signaling and gene regulation. Biophysical Journal. 101:757-763. https://doi.org/10.1016/j.bpj.2011.06.047S75776310