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Models of Mechanics and Growth in Developmental Biology: A Computational Morphodinamics approach

Bozorg, Behruz LU (2016)
Abstract
Recent evidence has revealed the role of mechanical cues in the development of shapes in organisms. This thesis is an effort to test some of the fundamental hypotheses about the relation between mechanics and patterning in plants. To do this, we develop mechanical models designed to include specific features of plant cell walls. These are heterogeneous stiffness and material anisotropy as well as rates and directions of growth, which we then relate to different domains of the plant tissue.
In plant cell walls, anisotropic fiber deposition is the main controller of longitudinal growth. In our model, this is achieved spontaneously, by applying feedback from the maximal stress direction to the fiber orientation. We show that a stress... (More)
Recent evidence has revealed the role of mechanical cues in the development of shapes in organisms. This thesis is an effort to test some of the fundamental hypotheses about the relation between mechanics and patterning in plants. To do this, we develop mechanical models designed to include specific features of plant cell walls. These are heterogeneous stiffness and material anisotropy as well as rates and directions of growth, which we then relate to different domains of the plant tissue.
In plant cell walls, anisotropic fiber deposition is the main controller of longitudinal growth. In our model, this is achieved spontaneously, by applying feedback from the maximal stress direction to the fiber orientation. We show that a stress feedback model is in fact an energy minimization process. This can be considered as an evolutionary motivation for the emergence of a stress feedback mechanism. Then we add continuous growth and cell division to the model and employ the strain signal directing large growth deformations. We show the advantages of strain-based growth model for emergence of plant-like organ shapes as well as for reproducing microtubular dynamics in hypocotyls and roots. We also investigate possibilities for describing microtubular patterns, at root hair outgrowth sites according to stress patterns. Altogether, the work described in this thesis, provides a new improved growth model for plant tissue, where mechanical properties are handled with appropriate care in the event of growth driven by either molecular or mechanical signals. The model unifies the patterning process for several different plant tissues, from shoot to single root hair cells, where it correctly predict microtubular dynamics and growth patterns. In a long-term perspective, this understanding can propagate to novel technologies for improvement of yield in agriculture and the forest industry. (Less)
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author
supervisor
opponent
  • Research Director Godin, Christophe, INRIA, Montpellier, France
organization
publishing date
type
Thesis
publication status
published
subject
keywords
plants, morphodynamics, mechanics, anisotropy, growth, microtubules, microfibrils
pages
175 pages
publisher
Lund University, Faculty of Science, Department of Astronomy and Theoretical Physics
defense location
Department of Physics, Lecture hall A, L317, S├Âlvegatan 14A, Lund
defense date
2016-06-03 13:15
ISBN
978-91-7623-844-8
978-91-7623-845-5
language
English
LU publication?
yes
id
8259878a-7932-4e37-b240-41eb5f0f086f
date added to LUP
2016-12-06 16:06:13
date last changed
2017-02-02 10:23:56
@phdthesis{8259878a-7932-4e37-b240-41eb5f0f086f,
  abstract     = {Recent evidence has revealed the role of mechanical cues in the development of shapes in organisms. This thesis is an effort to test some of the fundamental hypotheses about the relation between mechanics and patterning in plants. To do this, we develop mechanical models designed to include specific features of plant cell walls. These are heterogeneous stiffness and material anisotropy as well as rates and directions of growth, which we then relate to different domains of the plant tissue.<br/>In plant cell walls, anisotropic fiber deposition is the main controller of longitudinal growth. In our model, this is achieved spontaneously, by applying feedback from the maximal stress direction to the fiber orientation. We show that a stress feedback model is in fact an energy minimization process. This can be considered as an evolutionary motivation for the emergence of a stress feedback mechanism. Then we add continuous growth and cell division to the model and employ the strain signal directing large growth deformations. We show the advantages of strain-based growth model for emergence of plant-like organ shapes as well as for reproducing microtubular dynamics in hypocotyls and roots. We also investigate possibilities for describing microtubular patterns, at root hair outgrowth sites according to stress patterns. Altogether, the work described in this thesis, provides a new improved growth model for plant tissue, where mechanical properties are handled with appropriate care in the event of growth driven by either molecular or mechanical signals. The model unifies the patterning process for several different plant tissues, from shoot to single root hair cells, where it correctly predict microtubular dynamics and growth patterns. In a long-term perspective, this understanding can propagate to novel technologies for improvement of yield in agriculture and the forest industry. },
  author       = {Bozorg, Behruz},
  isbn         = {978-91-7623-844-8},
  keyword      = {plants,morphodynamics,mechanics,anisotropy,growth,microtubules,microfibrils},
  language     = {eng},
  pages        = {175},
  publisher    = {Lund University, Faculty of Science, Department of Astronomy and Theoretical Physics},
  school       = {Lund University},
  title        = {Models of Mechanics and Growth in Developmental Biology: A Computational Morphodinamics approach},
  year         = {2016},
}