Mapping CO₂ fixation to two effective parameters: A framework toward data-informed species and model comparison

Area of Science:

• Plant Physiology
• Biophysics
• Computational Biology

Background:

• Improving crop yield and resilience requires understanding limitations in carbon dioxide (CO2) assimilation rate in plant leaves.
• Mechanistic models integrating diffusion, biochemistry, and geometry can resolve the combined effects of multiple traits.
• Existing models like simple serial resistance models neglect tissue geometry, while detailed anatomical models are computationally intensive and require hard-to-measure parameters.

Purpose of the Study:

• To develop a framework for systematic comparison of species and models for CO2 assimilation.
• To identify the essential level of model resolution for different plant species.
• To simplify the understanding of CO2 fixation limitations in leaves.

Main Methods:

• Developed a minimal reaction-diffusion model to reduce CO2 fixation in leaves to two key parameters.
• Created a compact phase space based on these parameters to identify rate-limiting regimes.
• Mapped diverse plant species onto this phase space to analyze limitations and model requirements.

Main Results:

• Identified three naturally emerging rate-limiting regimes: stomatal uptake, intercellular diffusion, and intracellular processes.
• Revealed dominant co-limitations by stomatal and intracellular processes across diverse species.
• Found an equal partition between species requiring spatially resolved leaf-scale models and those adequately described by intracellular models.

Conclusions:

• The study presents a scalable framework for interpreting complex trait data and bridging the gap between different modeling approaches.
• Model resolution for CO2 assimilation is species-specific, necessitating tailored modeling strategies.
• Understanding these limitations is crucial for enhancing crop yield and resilience through targeted trait improvement.