title: Cellular modelling of secondary radial growth in conifer trees: application to Pinus radiata (D. Don).
abstract: The radial growth of conifer trees proceeds from the dynamics of a merismatic tissue called vascular cambium or cambium. Cambium is a thin layer of active proliferating cells. The purpose of this paper was to model the main characteristics of cambial activity and its consecutive radial growth. Cell growth is under the control of the auxin hormone indole-3-acetic. The model is composed of a discrete part, which accounts for cellular proliferation, and a continuous part involving the transport of auxin. Cambium is modeled in a two-dimensional cross-section by a cellular automaton that describes the set of all its constitutive cells. Proliferation is defined as growth and division of cambial cells under neighbouring constraints, which can eliminate some cells from the cambium. The cell-growth rate is determined from auxin concentration, calculated with the continuous model. We studied the integration of each elementary cambial cell activity into the global coherent movement of macroscopic morphogenesis. Cases of normal and abnormal growth of Pinus radiata (D. Don) are modelled. Abnormal growth includes deformed trees where gravity influences auxin transport, producing heterogeneous radial growth. Cross-sectional microscopic views are also provided to validate the model's hypothesis and results.
authors.affiliation: Laboratoire Techniques de l'Imagerie, de la Modélisation et de la Cognition (TIMC UMR CNRS 5525), Institut de l'Ingénierie et de l'Information de Santé, Faculté de Médecine, 38706, La Tronche Cedex, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: Forest
authors.forename: Jacques
authors.initials: J
authors.lastname: Demongeot
authors.forename: Jacques
authors.initials: J
authors.lastname: Demongeota
mesh_terms: D001693:Biological Transport, Active; D049109:Cell Proliferation; D007210:Indoleacetic Acids / Q000378:metabolism; D008433:Mathematics; D008954:Models, Biological; D028223:Pinus / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators