Segmentation of a microCT scan of <em>Nymphaea</em> sp., with cells (green), airspace (white), and veins (blue). Image by Mason Earles.
Segmentation of a microCT scan of Nymphaea sp., with cells (green), airspace (white), and veins (blue). Image by Mason Earles.

My current funded research is exploring the diversity between plant species in cellular organisation or architecture within leaves. Building from state-of-the-art 3D leaf imaging through high resolution X-ray computed tomography (microCT), will allow to present the leaf anatomical features properties in their true 3D nature and to accurately describe their importance in the leaf economic spectrum through their coordination with other leaf traits, allowing to scale up from leaf anatomy to the modelling of how leaf types are affected by a changing environment.
This project’s main collaborator is Mason Earles (postdoc, Yale University).

One leaf feature of importance is the mesophyll surface area exposed to intercellular airspace per leaf area (Sm) is closely associated with CO2 diffusion and photosynthetic rates. Sm is typically estimated from two-dimensional (2D) leaf sections and corrected for the three-dimensional (3D) geometry of mesophyll cells, leading to potential differences between the estimated and actual cell surface area. We have compared four published methods to estimate Sm in 2D to 3D estimates from microCT.

Using this method to validate published data, a database has been built to evaluate if there is a change in Sm and other airspace surface area ratios with the appearance of angiosperms. By considering the exposed surface of the mesophyll to the intercellular air space on a leaf or mesophyll volume rather than leaf area basis, we demonstrate that non-basal angiosperms have constructed leaves with more surface per volume.

Publications

Earles JM, Théroux-Rancourt G, Gilbert ME, McElrone A, Brodersen C (2018) Beyond porosity: 3D leaf intercellular airspace traits that impact mesophyll conductance. Plant Physiology 178(1), 148–162.

Théroux-Rancourt G, Earles JM, Gilbert ME, Zwieniecki MA, Boyce CK, McElrone A, Brodersen C (2017) The bias of a 2D view: Comparing 2D and 3D mesophyll surface area estimates using non-invasive imaging of internal leaf structure. New Phytologist doi: 10.1111/nph.14687

Conference abstract

Théroux Rancourt G, Earles JM, Gilbert ME, Zwieniecki MA, Boyce CK, McElrone A, Brodersen C (2017) Angiosperms evolved a higher mesophyll surface area per volume to maximize exchange surface under a low CO2 world. In: Geophysical Research Abstracts, Vol. 19, EGU2017-9904 (EGU General Assembly 2017, April 23-28, 2017, Vienna, Austria.)