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A Model Analysis of Mechanisms for Radial Microtubular Patterns at Root Hair Initiation Sites

Krupinski, Pawel LU ; Bozorg, Behruz LU ; Larsson, André LU ; Pietra, Stefano; Grebe, Markus and Jönsson, Henrik LU (2016) In Frontiers in Plant Science 7.
Abstract

Plant cells have two main modes of growth generating anisotropic structures. Diffuse growth where whole cell walls extend in specific directions, guided by anisotropically positioned cellulose fibers, and tip growth, with inhomogeneous addition of new cell wall material at the tip of the structure. Cells are known to regulate these processes via molecular signals and the cytoskeleton. Mechanical stress has been proposed to provide an input to the positioning of the cellulose fibers via cortical microtubules in diffuse growth. In particular, a stress feedback model predicts a circumferential pattern of fibers surrounding apical tissues and growing primordia, guided by the anisotropic curvature in such tissues. In contrast, during the... (More)

Plant cells have two main modes of growth generating anisotropic structures. Diffuse growth where whole cell walls extend in specific directions, guided by anisotropically positioned cellulose fibers, and tip growth, with inhomogeneous addition of new cell wall material at the tip of the structure. Cells are known to regulate these processes via molecular signals and the cytoskeleton. Mechanical stress has been proposed to provide an input to the positioning of the cellulose fibers via cortical microtubules in diffuse growth. In particular, a stress feedback model predicts a circumferential pattern of fibers surrounding apical tissues and growing primordia, guided by the anisotropic curvature in such tissues. In contrast, during the initiation of tip growing root hairs, a star-like radial pattern has recently been observed. Here, we use detailed finite element models to analyze how a change in mechanical properties at the root hair initiation site can lead to star-like stress patterns in order to understand whether a stress-based feedback model can also explain the microtubule patterns seen during root hair initiation. We show that two independent mechanisms, individually or combined, can be sufficient to generate radial patterns. In the first, new material is added locally at the position of the root hair. In the second, increased tension in the initiation area provides a mechanism. Finally, we describe how a molecular model of Rho-of-plant (ROP) GTPases activation driven by auxin can position a patch of activated ROP protein basally along a 2D root epidermal cell plasma membrane, paving the way for models where mechanical and molecular mechanisms cooperate in the initial placement and outgrowth of root hairs.

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author
organization
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type
Contribution to journal
publication status
published
subject
in
Frontiers in Plant Science
volume
7
publisher
Frontiers
external identifiers
  • scopus:84994462004
  • wos:000386484400001
ISSN
1664-462X
DOI
10.3389/fpls.2016.01560
language
English
LU publication?
yes
id
d781b4ef-42c4-46c8-a71e-bb2126cb73f3
date added to LUP
2016-12-06 14:57:55
date last changed
2017-08-06 05:14:38
@article{d781b4ef-42c4-46c8-a71e-bb2126cb73f3,
  abstract     = {<p>Plant cells have two main modes of growth generating anisotropic structures. Diffuse growth where whole cell walls extend in specific directions, guided by anisotropically positioned cellulose fibers, and tip growth, with inhomogeneous addition of new cell wall material at the tip of the structure. Cells are known to regulate these processes via molecular signals and the cytoskeleton. Mechanical stress has been proposed to provide an input to the positioning of the cellulose fibers via cortical microtubules in diffuse growth. In particular, a stress feedback model predicts a circumferential pattern of fibers surrounding apical tissues and growing primordia, guided by the anisotropic curvature in such tissues. In contrast, during the initiation of tip growing root hairs, a star-like radial pattern has recently been observed. Here, we use detailed finite element models to analyze how a change in mechanical properties at the root hair initiation site can lead to star-like stress patterns in order to understand whether a stress-based feedback model can also explain the microtubule patterns seen during root hair initiation. We show that two independent mechanisms, individually or combined, can be sufficient to generate radial patterns. In the first, new material is added locally at the position of the root hair. In the second, increased tension in the initiation area provides a mechanism. Finally, we describe how a molecular model of Rho-of-plant (ROP) GTPases activation driven by auxin can position a patch of activated ROP protein basally along a 2D root epidermal cell plasma membrane, paving the way for models where mechanical and molecular mechanisms cooperate in the initial placement and outgrowth of root hairs.</p>},
  articleno    = {1560},
  author       = {Krupinski, Pawel and Bozorg, Behruz and Larsson, André and Pietra, Stefano and Grebe, Markus and Jönsson, Henrik},
  issn         = {1664-462X},
  language     = {eng},
  publisher    = {Frontiers},
  series       = {Frontiers in Plant Science},
  title        = {A Model Analysis of Mechanisms for Radial Microtubular Patterns at Root Hair Initiation Sites},
  url          = {http://dx.doi.org/10.3389/fpls.2016.01560},
  volume       = {7},
  year         = {2016},
}