The mechanics of surf ace expansion anisotropy in Medicago truncatula root hairs
The mechanics of surf ace expansion anisotropy in Medicago truncatula root hairs
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DOI：
10.1104/pp.104.043752
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发表时间：
2004-10-01
期刊：
影响因子：
7.4
通讯作者：
Shaw, SL
中科院分区：
文献类型：
--
作者：
Dumais, J;Long, SR;Shaw, SL
尖端生长细胞的壁膨胀随位置和方向的变化而变化。在短毛紫花苜蓿的根毛中，细胞壁的扩张表现出强烈的子午梯度，在细胞的极附近最大。根毛细胞也表现出显著的膨胀各向异性，即在大部分圆顶表面上，周向壁的膨胀率超过子向的膨胀率。同时对膨胀率和细胞壁应力的测量表明，细胞壁的延伸性必须沿着细胞子午线突然变化，以维持细胞壁膨胀的梯度。为了确定膨胀各向异性的力学基础，我们将壁面膨胀的测量结果与完全各向同性、横向各向同性或完全各向异性的壁面结构模型预测的膨胀模式进行了比较。我们的结果表明，基于横向各向同性壁面结构的模型可以很好地拟合数据，尽管完全各向异性模型提供了最佳的整体拟合。我们讨论了如何在微观结构水平上控制这种机械性能。
Wall expansion in tip-growing cells shows variations according to position and direction. In Medicago truncatula root hairs, wall expansion exhibits a strong meridional gradient with a maximum near the pole of the cell. Root hair cells also show a striking expansion anisotropy, i.e. over most of the dome surface the rate of circumferential wall expansion exceeds the rate of meridional expansion. Concomitant measurements of expansion rates and wall stresses reveal that the extensibility of the cell wall must vary abruptly along the meridian of the cell to maintain the gradient of wall expansion. To determine the mechanical basis of expansion anisotropy, we compared measurements of wall expansion with expansion patterns predicted from wall structural models that were either fully isotropic, transversely isotropic, or fully anisotropic. Our results indicate that a model based on a transversely isotropic wall structure can provide a good fit of the data although a fully anisotropic model offers the best fit overall. We discuss how such mechanical properties could be controlled at the microstructural level.