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

Cornell University, Ithaca NY

Investigators

Abstract

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.