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Root branching is a major determinant of overall plant root system architecture, yet precise mechanisms of particularly the earliest steps in lateral root formation and its adaptation to environmental conditions remain poorly understood. In our lab we integrate experimental data with dynamic multi-scale modeling to arrive at a mechanistic understanding of these processes. A critical aspect of these models is that they enable us to investigate the interplay between developmental hormonal-genetic regulatory networks, environmental signalling networks and growth processes. This enables us on the one hand to establish what is necessary and sufficient to explain certain processes and how properties emerge, yet also predict the type of players we are missing, or perform experiments that in the lab would be impossible like letting certain cell
layers grow but not others to investigate their relative importance.
I will discuss how using these models we compare the likelihood and differential predictions of three competing hypotheses for the earliest, periodic stages of lateral root formation, the so-called root clock driving gene expression oscillations, periodic apoptosis of the lateral root cap repetitive enhancing auxin influx, and so-called reflux-and-growth where periodic cell size variations drive repetitive changes in auxin levels.
Assuming reflux-and-growth mediated lateral root priming I will next show preliminary results of how hydropatterning and xerobranching affect priming and prebranch site formation, and how nitrate levels may also play a role.
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