Postdoctoral Fellowship: PRFB: Investigating Unsaturated Leaf Airspaces

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2024, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment, and Phenotypes. The fellowship supports research and training of the fellow that will contribute to the area of Rules of Life in innovative ways. Plants breathe through small pores on their leaves called stomata that open to allow the uptake of carbon dioxide into leaf airspaces for photosynthesis, but at the expense of losing water.

This exchange of water for carbon impacts plant growth, stress response, and function. It has been assumed that leaf airspaces are saturated with water vapor; however, this project will test this assumption, which is used to make important calculations in Earth systems models. If the project demonstrates these airspaces to be unsaturated, it would overturn decades of results and require significant changes.

Furthermore, if plants can control the amount of water vapor in their leaf airspaces, this ability could be harnessed to make crops that use less water. This investigation can help clarify how plants adapt to changing conditions, at scales from a single leaf to global ecosystems. Furthermore, the fellow will expand the participation of diverse communities in science through teaching, mentoring, and science outreach.

This project will investigate a potential new Rule of Life: that plants can selectively restrict the rate of water loss from leaves without restricting photosynthetic carbon gain. The fellow will use experimental and computational approaches to validate unsaturation in leaf airspaces and assess bias in existing models caused by unsaturation. Two hypotheses will be tested: H1) Leaf airspace unsaturation varies among plant taxa, and increases proportionally with evaporative demand (vapor pressure deficit) and H2) The incorrect assumption of airspace saturation leads to bias in calculated leaf traits, which in turn skews both predictions from models and understanding of the physiology and ecology of carbon-water balance.

To address H1, the fellow will use an experimental method to quantify unsaturation in a wide range of taxa and under different environmental conditions. For H2, the fellow will use computational approaches to quantify biases caused by unsaturation in leaf- and canopy-scale models of carbon and water exchange. The fellow will gain training and expertise in plant ecophysiology and biophysics, and will engage in teaching and mentoring activities for historically underrepresented groups.

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.