title: Mathematical Modeling of the Dynamics of Shoot-Root Interactions and Resource Partitioning in Plant Growth.
abstract: Plants are highly plastic in their potential to adapt to changing environmental conditions. For example, they can selectively promote the relative growth of the root and the shoot in response to limiting supply of mineral nutrients and light, respectively, a phenomenon that is referred to as balanced growth or functional equilibrium. To gain insight into the regulatory network that controls this phenomenon, we took a systems biology approach that combines experimental work with mathematical modeling. We developed a mathematical model representing the activities of the root (nutrient and water uptake) and the shoot (photosynthesis), and their interactions through the exchange of the substrates sugar and phosphate (Pi). The model has been calibrated and validated with two independent experimental data sets obtained with Petunia hybrida. It involves a realistic environment with a day-and-night cycle, which necessitated the introduction of a transitory carbohydrate storage pool and an endogenous clock for coordination of metabolism with the environment. Our main goal was to grasp the dynamic adaptation of shoot:root ratio as a result of changes in light and Pi supply. The results of our study are in agreement with balanced growth hypothesis, suggesting that plants maintain a functional equilibrium between shoot and root activity based on differential growth of these two compartments. Furthermore, our results indicate that resource partitioning can be understood as the emergent property of many local physiological processes in the shoot and the root without explicit partitioning functions. Based on its encouraging predictive power, the model will be further developed as a tool to analyze resource partitioning in shoot and root crops.
authors.affiliation: Dept. of Mathematics, University of Fribourg, Fribourg, Switzerland.
authors.forename: Chrystel
authors.initials: C
authors.lastname: Feller
authors.affiliation: Dept. of Biology, University of Fribourg, Fribourg, Switzerland.
authors.forename: Patrick
authors.initials: P
authors.lastname: Favre
authors.affiliation: Dept. of Mathematics, University of Fribourg, Fribourg, Switzerland.
authors.forename: Ales
authors.initials: A
authors.lastname: Janka
authors.affiliation: Institute of Agricultural Sciences, ETH Zürich, Zürich, Switzerland.
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Zeeman
authors.affiliation: Dept. of Mathematics, University of Fribourg, Fribourg, Switzerland.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Gabriel
authors.affiliation: Dept. of Biology, University of Fribourg, Fribourg, Switzerland.
authors.forename: Didier
authors.initials: D
authors.lastname: Reinhardt
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000528:radiation effects; D003198:Computer Simulation; D008027:Light; D008954:Models, Biological; D032306:Petunia / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D052585:Phloem / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D010710:Phosphates / Q000378:metabolism / Q000494:pharmacology; D063245:Plant Development / Q000187:drug effects / Q000528:radiation effects; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D018520:Plant Shoots / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D015203:Reproducibility of Results
chemical_list: D010710:Phosphates