Dynamic modelling of limitations on improving leaf CO2 assimilation under fluctuating irradiance
Alejandro Morales1, Elias Kaiser2, Xinyou Yin1
1Centre for Crop Systems Analysis, Wageningen University & Research, Wageningen, The Netherlands.
Plant, Cell & Environment
|December 16, 2017
Summary
A new dynamic model enhances understanding of leaf CO2 assimilation by incorporating factors like non-photochemical quenching and enzyme regulation. This model identifies key limitations and potential improvements for photosynthesis under fluctuating light.
Area of Science:
- Plant Physiology
- Photosynthesis Research
- Computational Biology
Background:
- Traditional steady-state models do not fully capture the dynamic nature of photosynthesis.
- Leaf CO2 assimilation is influenced by various regulatory processes and environmental factors like fluctuating light.
Purpose of the Study:
- To develop and validate a dynamic model of leaf CO2 assimilation.
- To investigate the impact of kinetic limitations on photosynthetic efficiency under fluctuating irradiance.
- To identify key regulatory processes limiting CO2 assimilation.
Main Methods:
- Extended a canonical steady-state model to include dynamic effects: non-photochemical quenching (qE), chloroplast movement, photoinhibition, Calvin cycle enzyme regulation, metabolite concentrations, and CO2 diffusion.
- Calibrated and tested the model using gas exchange and chlorophyll fluorescence data from Arabidopsis thaliana, including wild types and mutants affecting Rubisco activity, qE, and sucrose synthesis.
- Performed in silico simulations to quantify potential improvements in CO2 assimilation by removing kinetic limitations.
Main Results:
- The model successfully predicted CO2 assimilation in various Arabidopsis genotypes under different light conditions.
- In silico analysis revealed that the activation rates of Calvin cycle enzymes and stomatal opening were the most limiting factors for CO2 assimilation under fluctuating light (up to 17% improvement).
- Relaxation of non-photochemical quenching and chloroplast movement significantly impacted average low-irradiance CO2 assimilation (up to 10% improvement).
- Synergistic effects were observed, with simultaneous removal of all kinetic limitations leading to substantial improvements (up to 32%).
Conclusions:
- Dynamic modeling provides a more comprehensive understanding of leaf CO2 assimilation compared to steady-state approaches.
- Kinetic limitations in enzyme activation and stomatal conductance are critical for optimizing photosynthesis under variable light.
- Targeting multiple regulatory processes simultaneously holds the greatest potential for enhancing photosynthetic efficiency.
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