Sun-induced Chl fluorescence and its importance for biophysical modeling of photosynthesis based on light reactions

Lianhong Gu, Jimei Han, Jeffrey D. Wood, Christine Y.Y. Chang, Ying Sun

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177 Scopus citations

Abstract

Recent progress in observing sun-induced Chl fluorescence (SIF) provides an unprecedented opportunity to advance photosynthesis research in natural environments. However, we still lack an analytical framework to guide SIF studies and integration with the well-developed active fluorescence approaches. Here, we derive a set of coupled fundamental equations to describe the dynamics of SIF and its relationship with C3 and C4 photosynthesis. These equations show that, although SIF is dynamically as complex as photosynthesis, the measured SIF simplifies photosynthetic modeling from the perspective of light reactions by integrating over the dynamic complexities of photosynthesis. Specifically, the measured SIF contains direct information about the actual electron transport from photosystem II to photosystem I, giving a quantifiable link between light and dark reactions. With much-reduced requirements on inputs and parameters, the light-reactions-centric, SIF-based biophysical model complements the traditional, dark-reactions-centric biochemical model of photosynthesis. The SIF–photosynthesis relationship, however, is nonlinear. This is because photosynthesis saturates at high light whereas SIF has a stronger tendency to keep increasing, as fluorescence quantum yield has a relatively muted sensitivity to light levels. Successful applications of the SIF-based model of photosynthesis will depend on a predictive understanding of several previously underexplored physiological and biophysical processes. Advances can be facilitated by coordinated efforts in plant physiology, remote sensing, and eddy covariance flux observations.

Original languageEnglish
Pages (from-to)1179-1191
Number of pages13
JournalNew Phytologist
Volume223
Issue number3
DOIs
StatePublished - Aug 2019

Funding

We thank Dr Rich Norby for encouraging the writing of this paper, Dr Yang Song for checking the derivations of all equations, and three anonymous reviewers for constructive comments. This research is supported by the US Department of Energy (DOE), Office of Science, Biological and Environmental Research Program. ORNL is managed by UT-Battelle, LLC, for DOE under contract DE-AC05-00OR22725. JH acknowledges the support of the China Scholarship Council via her mentors Dr Wangfeng Zhang and Dr Yali Zhang at Shihezi University.

FundersFunder number
Biological and Environmental Research program
US Department of Energy
U.S. Department of Energy
Office of Science
Oak Ridge National LaboratoryDE-AC05-00OR22725
Shihezi University
China Scholarship Council

    Keywords

    • biochemical models of photosynthesis
    • biophysical models of photosynthesis
    • dark reactions
    • light reactions
    • nonphotochemical quenching
    • reaction centers
    • sun-induced Chl fluorescence (SIF)

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