Weber Alain, Braybrook Siobhan, Huflejt Michal, Mosca Gabriella, Routier-Kierzkowska Anne-Lise, Smith Richard S
Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland.
Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland Sainsbury Laboratory, Bateman Street, Cambridge, CB2 1LR, UK.
J Exp Bot. 2015 Jun;66(11):3229-41. doi: 10.1093/jxb/erv135. Epub 2015 Apr 7.
Growth in plants results from the interaction between genetic and signalling networks and the mechanical properties of cells and tissues. There has been a recent resurgence in research directed at understanding the mechanical aspects of growth, and their feedback on genetic regulation. This has been driven in part by the development of new micro-indentation techniques to measure the mechanical properties of plant cells in vivo. However, the interpretation of indentation experiments remains a challenge, since the force measures results from a combination of turgor pressure, cell wall stiffness, and cell and indenter geometry. In order to interpret the measurements, an accurate mechanical model of the experiment is required. Here, we used a plant cell system with a simple geometry, Nicotiana tabacum Bright Yellow-2 (BY-2) cells, to examine the sensitivity of micro-indentation to a variety of mechanical and experimental parameters. Using a finite-element mechanical model, we found that, for indentations of a few microns on turgid cells, the measurements were mostly sensitive to turgor pressure and the radius of the cell, and not to the exact indenter shape or elastic properties of the cell wall. By complementing indentation experiments with osmotic experiments to measure the elastic strain in turgid cells, we could fit the model to both turgor pressure and cell wall elasticity. This allowed us to interpret apparent stiffness values in terms of meaningful physical parameters that are relevant for morphogenesis.
植物的生长源于遗传网络与信号网络以及细胞和组织的力学特性之间的相互作用。最近，针对理解生长的力学方面及其对基因调控的反馈的研究再度兴起。这在一定程度上是由用于测量植物细胞体内力学特性的新型微压痕技术的发展所推动的。然而，压痕实验的解释仍然是一项挑战，因为力的测量结果是由膨压、细胞壁刚度以及细胞和压头的几何形状共同作用产生的。为了解释这些测量结果，需要一个精确的实验力学模型。在这里，我们使用了具有简单几何形状的植物细胞系统——烟草Bright Yellow-2（BY-2）细胞，来研究微压痕对各种力学和实验参数的敏感性。通过使用有限元力学模型，我们发现，对于在膨压细胞上进行的几微米的压痕，测量结果主要对膨压和细胞半径敏感，而对压头的确切形状或细胞壁的弹性特性不敏感。通过用渗透实验补充压痕实验以测量膨压细胞中的弹性应变，我们可以使模型与膨压和细胞壁弹性相匹配。这使我们能够根据与形态发生相关的有意义的物理参数来解释表观刚度值。
