Transitions: Creating a Trans-Disciplinary Approach to Discover Multi-Scale Control Mechanisms of Plant Morphogenesis

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。在作物物种中，植物的结构是产量的主要决定因素，可以定义其作为可再生生物材料的价值。细胞是建筑特征的基石，它们的生长是由巨大的内部压力驱动的，这种压力使细胞膨胀，并使坚硬的外部细胞受到非常高的拉伸力。细胞壁的材料特性决定了在很大范围的空间尺度上的生长模式。植物生物学的一个主要挑战是了解细胞内的遗传途径和蛋白质如何控制多糖的细胞外特性，从而决定生长模式。细胞内的蛋白质机器需要解读来自细胞壁的信息，这样才能预测细胞大小和形状的变化。植物生长系统可以被认为是基因编码的生物力学机器，以可预测的方式自我组装。由于缺乏将物理学和材料科学的概念与植物遗传学和细胞生物学的概念结合起来的跨学科方法，揭示潜在的控制机制的进展受到阻碍。生物学家迫切需要能够开发和充分表征植物发育的机械模型，为理解植物形态发生的细胞机制和将这些知识下游应用于农业提供知识基础。该项目的研究和学习活动将为分析和操纵增长模式提供新的方法。工程和生物学领域的知名专家和初级科学家将广泛地将机械建模和微力学分析与植物细胞生物学结合起来。研究团队将创建学习程序，使这种交叉训练普遍化，并制作更多用户友好的模型，可以被研究和教育社区广泛采用。美国救援计划的资金为这位调查员在职业生涯的关键阶段提供了支持。植物形态控制是一个多尺度的综合过程，在这个过程中，细胞骨架和细胞壁系统相互作用，产生适应性的生长模式。然而，我们对亚细胞生长模式如何确定以及它们如何影响细胞、组织和器官水平表型的理解尚不清楚。历史上关于均匀扩散生长的假设可能是不正确的，因为大多数细胞类型具有异质生长模式。此外，很难定量预测管壁中的拉伸力模式，因为它们取决于膨胀压力、多种几何特征和管壁的材料特性。有限元建模提供了一个有效的途径，因为它将细胞模拟为薄壁加压壳，可以用于定量模拟具有真实细胞和组织几何形状的张力和生长模式。该模型还对驱动植物细胞生长的细胞壁异质性的位置和类型以及细胞骨架如何感知细胞壁力做出了具体的预测。这个“向卓越过渡”项目将开发一个新颖的学习和研究项目，广泛地使生物学家和工程师能够严格地整合有限元建模、实验验证和模型改进。这种方法以及将被分析的单细胞和器官系统，有可能定义从纳米到厘米尺度上操作的可概括的形态发生“规则”，以编程功能特征。这项研究将作为一个框架，创建更复杂的模型，提供足够的细节，为基因工程植物表型的策略提供信息。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).In crop species, the architecture of the plant is a primary determinant of yield and can define its value as a renewable biomaterial. Cells are the building blocks of architectural traits and their growth is driven by a large internal pressure that makes the cells turgid and subjects the tough outer cell to very high tensile forces. The material properties of the cell wall determine the patterns of growth across a wide range of spatial scales. A major challenge in plant biology is to understand how genetic pathways and proteins inside the cell control the extracellular properties of polysaccharides to dictate growth patterns. The protein machineries inside the cell need to interpret information from the cell wall so that changes in cell size and shape can be predictable. Plant growth systems can be thought of as genetically encoded biomechanical machines that self-assemble in predictable ways. Progress in unravelling the underlying control mechanisms has been hindered by the lack of interdisciplinary approaches that combine the concepts of physics and material science with those of plant genetics and cell biology. There is a strong need for biologists to be able to develop and fully characterize mechanical models of plant development that provide the knowledge base for understanding the cellular mechanisms of plant morphogenesis and the downstream application of this knowledge to agriculture. The research and learning activities in this project will seed new approaches to analyze and manipulate growth patterns. Established experts and junior scientists in engineering and biology will broadly integrate mechanical modelling and micromechanical analyses with plant cell biology. The research team will create learning programs to make this cross-training generalizable and to make more user friendly models that can be widely adopted by the research and educational communities. American Rescue Plan funding provides support for this investigator at a critical stage in his career.Plant morphology control is a multi-scale integrated process in which cytoskeletal and cell wall systems interact to generate adaptive growth patterns. However, our understanding of how subcellular growth patterns are determined and how they scale to influence cell-, tissue-, and organ-level phenotypes are not known. Historical assumptions about uniform diffuse growth are likely incorrect as most cell types have heterogeneous growth patterns. In addition, it has been difficult to quantitatively predict tensile force patterns in the wall, because they depend on turgor pressure, multiple types of geometric features, and the material properties of the wall. Finite element modelling provides an efficient path forward because it simulates the cells as a thin-walled pressurized shells and can be used to quantitatively simulate the tensile forces and growth patterns with realistic cell and tissue geometries. The model also makes specific predictions about the location and type of cell wall heterogeneity that drive plant cell growth and how cell wall forces can be sensed by the cytoskeleton. This “Transitions to Excellence” project will develop a novel learning and research program that will broadly enable biologists and engineers to rigorously integrate finite element modelling, experimental validation, and model refinement. This approach and the single cell and organ systems that will be analyzed, have the potential to define generalizable morphogenesis “rules” that operate from the nanometer to centimeter scales to program functional traits. This research will serve as a framework to create more sophisticated models with sufficient detail to inform strategies to genetically engineer plant phenotypes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.