In this paper we consider the high–affinity nitrate acquisition in plant roots. This process is governed by a mechanism including two loops of opposite signs we call Incoherent FeedBack (IFB) loop. A positive feedback loop acting in the short term, increases the intake when the roots are exposed to nitrate. An additional negative loop drastically reduces the acquisition in the long run by inhibiting the synthesis of transporters. We propose a model that fits nicely the experimental data. We investigate about the robustness of the model proving its structural stability, namely, stability for all possible parameters under some technical assumptions. We compare our model to the well known Incoherent FeedForward (IFF) loop which is a very popular network motif.
