Optimizing the Electron Transport Chain to Sustainably Improve Photosynthesis: Insights from a New Photosynthesis Model

Authors

Lianhong Gu* ([email protected]), Paul J. Hanson

Institutions

Oak Ridge National Laboratory, Oak Ridge, TN

URLs

Abstract

Genetically improving photosynthesis is a key strategy for boosting crop production to meet rising food and fuel demands by a rapidly growing global population in a warming climate. Many components of the photosynthetic apparatus have been targeted for genetic modification for improving photosynthesis. Successful translation of these modifications into increased plant productivity in fluctuating environments will depend on whether the electron transport chain (ETC) can support the increased electron transport rate without risking overreduction and photodamage. At the present atmospheric conditions, ETC appears suboptimal and will likely have to be modified to support proposed photosynthetic improvements and to maintain energy balance.

Based on a new model of photosynthetic electron transport (Gu et al. 2022, 2023), this study derives photochemical equations to quantify the transport capacity and corresponding reduction level based on the kinetics of redox reaction along the ETC. Using these theoretical equations and measurements from diverse C3 and C4 species across environments obtained by LeafWeb (www.leafweb.org), scientists identified several strategies that can simultaneously increase the transport capacity and decrease the reduction level of ETC. These include (1) increasing the abundances of reaction centers, cytochrome b6f complex, and mobile electron carriers; (2) improving their redox kinetics; and (3) decreasing the fraction of secondary quinone-nonreducing photosystem II reaction centers. Findings facilitate the development of sustainable photosynthetic systems for greater crop yields.

References

Gu, L., et al. 2023. “An Exploratory Steady-State Redox Model of Photosynthetic Linear Electron Transport for Use in Complete Modeling of Photosynthesis for Broad Applications,” Plant, Cell & Environment 46(5), 1540–1561. DOI:10.1111/pce.14563.

Gu, L., et al. 2022. “Granal Thylakoid Structure and Function: Explaining an Enduring Mystery of Higher Plants,” New Phytologist 236(2), 319–329. DOI:10.1111/nph.18371.