Plants Trade Tolerance with Resilience to Extreme Temperatures

The Science

The maximum quantum yield of photosystem II (F_PSIImax) is a key parameter of the light reactions that influences the electron transport rate needed for supporting the biochemical reactions of photosynthesis. Carbon cycle models often treat F_PSIImax as a constant, even though plant stress is expected to decrease it. This study aims to understand and quantify temperature’s effect on the efficiency of light conversion to electron transport for photosynthesis across plant functional types (PFTs) and climate. Researchers synthesized F_PSIImax values from pulse-amplitude–modulated fluorometry measurements in response to variable temperatures across the globe. The study found F_PSIImax is strongly affected by prevailing temperature regimes with declined values in both hot and cold conditions.

The Impact

This study points to a quantitative approach for improving electron transport and photosynthetic productivity modeling under changing climates at regional and global scales. Future work will focus on isolating the temperature-dependent changes between the variables.

Summary

Modeling terrestrial gross primary productivity (GPP) is central to predicting the global carbon cycle. Much interest has been focused on the environmentally induced dynamics of photosystem energy partitioning and how improvements in the description of such dynamics assist the prediction of light reactions of photosynthesis and therefore GPP. F_PSIImax is generally treated as a constant in biochemical photosynthetic models even though a constant F_PSIImax is expected only for non-stressed plants. Researchers synthesized reported F_PSIImax values from pulse-amplitude–modulated fluorometry measurements in response to variable temperatures across the globe. They found F_PSIImax is strongly affected by prevailing temperature regimes with declined values in both hot and cold conditions. To understand the spatiotemporal variability in F_PSIImax, researchers analyzed the temperature effect on F_PSIImax across PFT and habitat climatology. The analysis showed that for plants with broad latitudinal distributions or in regions with extreme temperature variability, temperature’s impact on F_PSIImax is shaped more by climate than by PFT. There is a trade-off between the temperature range within which F_PSIImax remains maximal and the overall rate of decline of F_PSIImax outside the temperature range, such that species cannot be simultaneously tolerant and resilient to extreme temperatures.

Principal Investigator

Lianhong Gu
Oak Ridge National Laboratory
[email protected]

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
[email protected]

Funding

The research has been supported by the University of Arizona Faculty start-up funding and the Biological and Environmental Research program in the Department of Energy’s Office of Science, via the Oak Ridge National Laboratory Terrestrial Ecosystem Science (TES) Scientific Focus Area (SFA).

References