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

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.