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Dissecting the regulation of pollen tube growth by modeling the interplay of hydrodynamics, cell wall and ion dynamics

Liu, J.; Hussey, P.J.

Dissecting the regulation of pollen tube growth by modeling the interplay of hydrodynamics, cell wall and ion dynamics Thumbnail


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Abstract

Hydrodynamics, cell wall and ion dynamics are all important properties that regulate pollen tube growth. Currently, the two main pollen tube growth models, the cell wall model and the hydrodynamic model do not appear to be reconcilable. Here we develop an integrative model for pollen tube growth and show that our model reproduces key experimental observations: (1) that the hypertonic condition leads to a much longer oscillatory period and that the hypotonic condition halves the oscillatory period; (2) that oscillations in turgor are experimentally undetectable; (3) that increasing the extracellular calcium concentration or decreasing the pH decreases the growth oscillatory amplitude; (4) that knockout of Raba4d, a member of the Rab family of small GTPase proteins, decreases pollen tube length after germination for 24 h. Using the model generated here, we reveal that (1) when cell wall extensibility is large, pollen tube may sustain growth at different volume changes and maintain relatively stable turgor; (2) turgor increases if cell wall extensibility decreases; (3) increasing turgor due to decrease in osmolarity in the media, although very small, increases volume change. However, increasing turgor due to decrease in cell wall extensibility decreases volume change. In this way regulation of pollen tube growth by turgor is context dependent. By changing the osmolarity in the media, the main regulatory points are extracellular osmolarity for water flow and turgor for the volume encompassed by the cell wall. However, if the viscosity of cell wall changes, the main regulatory points are turgor for water flow and wall extensibility for the volume encompassed by the cell wall. The novel methodology developed here reveals the underlying context-dependent regulatory principle of pollen tube growth.

Citation

Liu, J., & Hussey, P. (2014). Dissecting the regulation of pollen tube growth by modeling the interplay of hydrodynamics, cell wall and ion dynamics. Frontiers in Plant Science, 5, Article 392. https://doi.org/10.3389/fpls.2014.00392

Journal Article Type Article
Acceptance Date Jul 22, 2014
Online Publication Date Aug 11, 2014
Publication Date Aug 11, 2014
Deposit Date Sep 9, 2014
Publicly Available Date Sep 9, 2014
Journal Frontiers in Plant Science
Publisher Frontiers Media
Peer Reviewed Peer Reviewed
Volume 5
Article Number 392
DOI https://doi.org/10.3389/fpls.2014.00392
Keywords Pollen tube growth, Mathematical modeling, Oscillatory dynamics, Interplay of hydrodynamics, Cell wall and ion dynamics, Regulation coefficients.

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http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Copyright © 2014 Liu and Hussey. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.






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