Wei C, Lintilhac P M, Tanguay J J
Department of Botany, Marsh Life Science Building, University of Vermont, Burlington, Vermont 05405-0086, USA.
Plant Physiol. 2001 Jul;126(3):1129-38. doi: 10.1104/pp.126.3.1129.
We have studied the elasticity and load bearing ability of plant tissue at the cellular level, using onion (Allium cepa) epidermal cells. The Young's modulus and Poisson's ratio of the cells were obtained by loading a tensile force on onion epidermal peels of different turgor pressures, and measuring the elongation and the lateral contraction of the peels. The Young's moduli and the Poisson's ratios ranged from 3.5 to 8.0 MPa and 0.18 to 0.30, respectively. To determine the effects of cell elasticity and turgor pressure on the cell's ability to bear load, we loaded a small glass ball onto a cell and measured the projected contact area between the ball and the cell. Unlike previous studies, we considered the cell as a whole entity, and utilized the Boussinesq's solution to derive the relevant equations that related the elastic parameters and cell deformation. For cells with a turgor pressure > or = 0.34 MPa, the predicted contact area agreed well with the measured area. The equations could also predict cell turgor pressure with a deviation from the measured value of 0.01 MPa. This study gives strong support to ball tonometry, a new method of measuring cell turgor pressure.
我们使用洋葱（葱属植物）表皮细胞在细胞水平上研究了植物组织的弹性和承载能力。通过对不同膨压的洋葱表皮施加拉伸力，并测量表皮的伸长和横向收缩，获得了细胞的杨氏模量和泊松比。杨氏模量和泊松比分别在3.5至8.0兆帕和0.18至0.30之间。为了确定细胞弹性和膨压对细胞承载能力的影响，我们将一个小玻璃球加载到一个细胞上，并测量球与细胞之间的投影接触面积。与之前的研究不同，我们将细胞视为一个整体，并利用布辛涅斯克解推导出了将弹性参数与细胞变形相关联的相关方程。对于膨压≥0.34兆帕的细胞，预测的接触面积与测量面积吻合良好。这些方程还可以预测细胞膨压，与测量值的偏差为0.01兆帕。本研究为测量细胞膨压的新方法——球压法提供了有力支持。
