Analysis of multi-scale biomechanical design principles of plant tissues and developmental processes

多细胞生物的进化涉及不同细胞类型之间的分工，这些细胞类型具有高度特异性的代谢和结构功能。这些干细胞分化细胞的起源是通过协调的细胞生长和成形而发生的，在植物中，这涉及新细胞壁材料的组装，即包裹所有植物细胞的坚硬多糖聚合物。植物细胞壁的机械特性决定了分化细胞的几何形状，从而决定了整个组织和器官的结构。人们对参与植物细胞发育的分子参与者给予了很多关注。然而，我们对控制复杂细胞几何形状（例如海绵叶叶肉或星形毛状体）生成的机械原理了解甚少。更难以捉摸的是整个组织的起源基础，需要协调的细胞成形和战略性的细胞-细胞分离。重要的是，组织结构必须协调代谢功能的要求与器官机械稳定性所需的结构特征。 拟议的研究计划将细胞生物学方法与微机械工程和计算模型相结合，旨在多尺度研究植物中的细胞和组织分化。具体来说，我们将研究细胞壁材料的亚细胞组装、细胞壁对细胞生长的调节以及通过细胞成形和局部细胞脱离进行的组织分化。这种方法将回答发育是如何发生的，并将通过机械测试来补充，以评估为什么某些组织结构有利于植物生存。我们将使用微观机械测试与微观监测相结合来检查植物组织在机械应力下的行为。生物物理细胞参数和高分辨率结构数据将为使用有限元方法构建的理论模拟模型提供信息。这些模型做出的预测将指导后续旨在验证植物发育概念基础的实验策略。该研究项目是高度跨学科的，因为它将各种细胞生物学方法（分子生物学、高端共焦激光扫描显微镜、活细胞成像）与微机械工程和计算建模相结合，并为来自多个学科的研究生提供了机会：生物学和数学/工程学。

The evolution of multi-cellular organisms implicates the division of labour between different cell types that assume highly specific metabolic and structural functions. The genesis of these differentiated cells from stem cells occurs through coordinated cell growth and shaping which in plants involves assembly of new cell wall materiala stiff polysaccharide polymer enveloping all plant cells. The mechanical properties of the plant cell wall determine the geometry of the differentiating cell and, by consequence, the architecture of the entire tissue and organ. Much attention has been devoted to the molecular players involved in plant cell development. However, we have a poor understanding of the mechanical principles that govern the generation of complex cell geometries such as those of the spongy leaf mesophyll or star-shaped trichomes. Even more elusive are the underpinnings of the genesis of entire tissues that require coordinated cell shaping and strategic cell-cell detachment. Importantly, tissue structure has to reconcile the requirements for metabolic functioning with the architectural features necessary for mechanical stability of the organ. The proposed research program combines cell biological approaches with micromechanical engineering and computational modeling with the aim to study cell and tissue differentiation in plants at multiple scales. Specifically, we will study the subcellular assembly of cell wall material, the regulation of cell growth by the cell wall, and the differentiation of tissues through cell shaping and local cell detachment. This approach will answer how development occurs and it will be complemented by mechanical testing to assess why certain tissue architectures are beneficial for plant survival. We will use micro-mechanical testing in combination with microscopic monitoring to examine how plant tissues behave under mechanical stress. Biophysical cellular parameters and high-resolution structural data will inform theoretical simulation models built using finite element methods. Predictions made by these models will guide subsequent experimental strategy designed to validate the conceptual underpinnings of plant development. This research program is highly interdisciplinary as it combines various cell biological approaches (molecular biology, high end confocal laser scanning microscopy, live cell imaging) with micromechanical engineering and computational modeling and it offers opportunities for graduate students from multiple disciplines: biology and mathematics/engineering.