Modeling and Analysis of Mesophyll Tissue Development in Leaves and Flowers Across Species*

Mesophyll tissue in plant leaves plays a critical role in providing mechanical stability and facilitating photosynthesis and displays a wide range of structural variation across species. However, little is known about the development of this tissue in three dimensions (3D). Early in development, the cells in mesophyll tissue are confluent. However, in mature leaves, the mesophyll tissue can either remain extremely dense or possess very dilute packing fractions comparable to highly porous gels. We hypothesize that the differences in the structural properties of mesophyll tissue are primarily driven by differences in cell stiffness, growth rate, and adhesion. We analyze 3D x-ray micro-computed tomography (microCT) scans of several species and quantify the variations in structure of the mesophyll during development and across species. We have also developed 3D deformable particle simulations to model mesophyll tissue development. We compare the results for the average shape parameter of the cells versus the porosity of mesophyll tissue in simulations and those observed in the microCT scans. Finally, we illustrate the variation in the physical properties of the cells that are required to recover the wide variation in mesophyll structural properties.