NSF-ANR: The Biophysical Basis of Flat Organ Morphogenesis From Fluctuating Cellular Growth (GrowFlat)

该项目的首要目标是了解树叶在生长过程中如何保持其扁平结构。叶片平整度是一个关键的农艺性状，因为它影响光合作用所需的光拦截和二氧化碳吸收的程度。这是一个跨学科的合作项目，汇集了法国研究生物物理学的实验室和美国研究植物细胞生物学的实验室，以获得控制叶片形状的细胞之间的机械相互作用的新见解。本项目将有助于培养跨学科的博士后和本科生科学家。这项工作将通过法国的外展活动向公众传播，如开放大学、克劳德·伯纳德·里昂大学；CNRS关于“还有什么有待发现”的论坛，以及在美国通过“STEM女孩”向中学女生推广。薄的组织，比如植物的叶子，通常是平的，而生长中的薄片的默认状态是弯曲的。如何达到平坦的形状？该项目在拟南芥叶片中解决了这个问题，这是一个适合生长实时成像、生物物理实验和基因操作的系统。这个项目将测试这样一个假设，即相邻细胞之间的生长差异（异质性）允许细胞感知叶片曲率的变化，并在叶片膨胀时纠正以保持平坦。具体来说，(i)细胞间生长差异、细胞力学和叶片平整度之间的关系将使用具有弯曲、卷曲或波浪状叶片的突变体来表征。（ii）将建立一个在三维空间中模拟薄活动生长片的理论框架，（iii）将通过模型预测和实验测试来表征平面度的组合调节。总之，拟议的研究将促进我们对在发育过程中产生可复制器官形状的生物物理机制的理解。这个美国/法国合作项目由美国国家科学基金会和法国国家研究机构支持，其中美国国家科学基金会资助美国研究者，法国国家研究机构资助法国合作伙伴。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。

The overarching goal of this project is to understand how leaves maintain their flat structure while they grow. Leaf flatness is a key agronomic trait because it affects the extent of light interception and carbon dioxide intake which are required for photosynthesis. This is an interdisciplinary collaborative project bringing together a laboratory in France that studies biophysics and a laboratory in the US that studies plant cell biology to gain new insights into the mechanical interactions between cells that control of leaf shape. This project will contribute to the interdisciplinary training of postdoctoral and undergraduate scientists. The work will be communicated to the public through outreach activities in France such as The Open University, Université Claude Bernard Lyon 1; the CNRS forum on What remains to be discovered and in the US through the Girls for STEM outreach to middle school girls. Thin tissues, such as plant leaves, are typically flat, whereas the default state of a growing thin sheet is curved. How is flat shape achieved? This project addresses this question in Arabidopsis leaves, a system amenable to live-imaging of growth, biophysical experiments, and genetic manipulation. This project will test the hypothesis that differences between neighboring cells in their growth (heterogeneity) allows the cells to sense variations in leaf curvature and correct to maintain flatness as the leaf expands. Specifically, (i) the relationship between cell-to-cell differences in growth, cell mechanics, and leaf flatness will be characterized using mutants with curved, crinkly or wavy leaves. (ii) a theoretical framework to model a thin active growing sheet in 3D space will be built, and (iii) the combinatorial regulation of flatness will be characterized through model predictions and experimental tests. Altogether, the proposed research will advance our understanding of the biophysical mechanisms that generate reproducible organ shapes during development.This collaborative US/France project is supported by the US National Science Foundation and the French Agence Nationale de la Recherche, where NSF funds the US investigator and ANR funds the partners in France.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.