The rate of net CO2 uptake is proportional to dim light and saturates when the light exceeds the plant's assimilation capacity. This simple relationship between constant light and photosynthesis becomes intriguingly complex when the light oscillates. The rates of photosynthesis may differ between the descending and ascending phases of light oscillation. This hysteresis changes with the frequency and amplitude of the light and reports on the dynamics of the photosynthetic reactions and their regulation. Here, we investigated the chlorophyll fluorescence response of Arabidopsis thaliana to light oscillating with three different amplitudes: 100-200, 100-400, and 100-800 μmol photons m-2 s-1, each with periods ranging from 1 s to 8 min. The light amplitudes and periods were chosen to represent light patterns often appearing in nature. Three genotypes were compared: wild-type Col-0 and npq1 and npq4 mutants that are incapacitated in the rapidly reversible energy-dependent non-photochemical quenching (qE). The experiments identified two major dynamic patterns. One was found in oscillation periods shorter than 30 s, characterized by constitutive hysteresis and non-linearity. The other was mainly formed by regulatory hysteresis, occurring when the oscillation periods were longer than 30 s. The mathematical model simulating the chlorophyll fluorescence dynamics qualitatively reproduced the constitutive and regulatory dynamic patterns observed in the experiments. The model simulations illustrated the dynamics of plastoquinone pool reduction and variables affecting non-photochemical quenching that form the constitutive and regulatory hysteresis types. The model simulations provided mechanistic insights into molecular processes forming the plant response to oscillating light.

• Keywords
• chlorophyll fluorescence, frequency domain, harmonics, mathematical model, photosynthesis,
• MeSH
• Arabidopsis * radiation effects   physiology   metabolism   genetics   MeSH
• Chlorophyll metabolism   MeSH
• Fluorescence MeSH
• Photosynthesis radiation effects   physiology   MeSH
• Arabidopsis Proteins metabolism   genetics   MeSH
• Light * MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Chlorophyll MeSH
• Arabidopsis Proteins MeSH

To keep up with the growth of human population and to circumvent deleterious effects of global climate change, it is essential to enhance crop yield to achieve higher production. Here we review mathematical models of oxygenic photosynthesis that are extensively used, and discuss in depth a subset that accounts for diverse approaches providing solutions to our objective. These include models (1) to study different ways to enhance photosynthesis, such as fine-tuning antenna size, photoprotection and electron transport; (2) to bioengineer carbon metabolism; and (3) to evaluate the interactions between the process of photosynthesis and the seasonal crop dynamics, or those that have included statistical whole-genome prediction methods to quantify the impact of photosynthesis traits on the improvement of crop yield. We conclude by emphasizing that the results obtained in these studies clearly demonstrate that mathematical modelling is a key tool to examine different approaches to improve photosynthesis for better productivity, while effective multiscale crop models, especially those that also include remote sensing data, are indispensable to verify different strategies to obtain maximized crop yields.

• Keywords
• C4 rice, Improving photosynthesis and crop yield, Leaf and crop models, Photorespiration bypasses, Photosynthesis models, Synthetic biology,
• MeSH
• Models, Biological MeSH
• Photosynthesis * physiology   MeSH
• Plant Leaves * physiology   metabolism   growth & development   MeSH
• Models, Theoretical MeSH
• Electron Transport MeSH
• Crops, Agricultural * growth & development   genetics   physiology   MeSH
• Publication type
• Journal Article MeSH
• Review MeSH