Capability of tip-growing plant cells to penetrate into extremely narrow gaps.

Naoki Yanagisawa,Tetsuya Higashiyama,Yoshikatsu Sato,Hideyuki Arata,Nagisa Sugimoto

doi:10.1038/s41598-017-01610-w

Naoki Yanagisawa, Tetsuya Higashiyama + Show 3 more

Open Access

https://doi.org/10.1038/s41598-017-01610-w

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Journal: Scientific Reports	Publication Date: May 3, 2017
Citations: 36	License type: open-access

Affiliation: Nagoya University, The University of Tokyo

Abstract

Plant cells are covered with rigid cell walls, yet tip-growing cells can elongate by providing new cell wall material to their apical regions. Studies of the mechanical properties of tip-growing plant cells typically involve measurement of the turgor pressure and stiffness of the cells’ apical regions. These experiments, however, do not address how living tip-growing cells react when they encounter physical obstacles that are not substantially altered by turgor pressure. To investigate this issue, we constructed microfabricated platforms with a series of artificial gaps as small as 1 μm, and examined the capability of tip-growing plant cells, including pollen tubes, root hairs, and moss protonemata, to penetrate into these gaps. The cells were grown inside microfluidic chambers and guided towards the gaps using microdevices customized for each cell type. All types of tip-growing cells could grow through the microgaps with their organelles intact, even though the gaps were much smaller than the cylindrical cell diameter. Our findings reveal the dramatic physiological and developmental flexibility of tip-growing plant cells. The microfluidic platforms designed in this study provide novel tools for the elucidation of the mechanical properties of tip-growing plant cells in extremely small spaces.

Highlights

Plant cells are covered with rigid cell walls, yet tip-growing cells can elongate by providing new cell wall material to their apical regions
5–6 hours after pollination, pollen tube (PT) emerged from the end of the cut style and continuously grew inside the microchannels, which were filled with growth medium
The gap became somewhat wider as the PT crossed it, suggesting that the turgor pressure was strong enough to deform the shape of the PDMS structure (Supplementary Fig. S2); the width of the gap was still much smaller than the diameter of the PT (~8 μm)

Summary

Introduction

Plant cells are covered with rigid cell walls, yet tip-growing cells can elongate by providing new cell wall material to their apical regions. Studies of the mechanical properties of tip-growing plant cells typically involve measurement of the turgor pressure and stiffness of the cells’ apical regions These experiments, do not address how living tip-growing cells react when they encounter physical obstacles that are not substantially altered by turgor pressure. Microfluidic devices originating from MEMS-based technology have received considerable attention from the plant science community[9,10,11]; recently, the penetrative force of tip-growing PTs was successfully measured using a polydimethylsiloxane (PDMS) microfluidic device by taking advantage of the elastic properties of PDMS12 These quantitative methods for measuring turgor pressure and stiffness in the apical cell wall are indispensable, especially for the investigation of the mechanical properties of tip-growing cells. We utilized this system to examine three types of tip-growing plant cells: PTs, root hairs, and moss protonemata

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