Enhancing the light reactions of photosynthesis: Strategies, controversies, and perspectives

Photosynthesis is central to life on Earth, employing sunlight, water, and carbon dioxide to produce chemical energy and oxygen. It is generally accepted that boosting its efficiency offers one promising way to increase crop yields under agronomically realistic conditions. Since the components, structure, and regulatory mech-anisms of the light reactions of photosynthesis are well understood, concepts for enhancing the process have been suggested and partially tested. These approaches vary in complexity, from targeting single com-ponents to comprehensive redesign of the whole process on the scales from single cells or tissues to whole canopies. Attempts to enhance light utilization per leaf, by decreasing pigmentation, increasing levels of photosynthetic proteins, prolonging the lifespan of the photosynthetic machinery, or massive reconfigura-tion of the photosynthetic machinery and the incorporation of nanomaterials, are discussed in this review first. Secondly, strategies intended to optimize the acclimation of photosynthesis to changes in the environ -ment are presented, including redesigning mechanisms to dissipate excess excitation energy (e.g., non-photochemical quenching) or reduction power (e.g., flavodiiron proteins). Moreover, schemes for improving acclimation, inspired by natural or laboratory-induced adaptation, are introduced. However, all these en-deavors are still in an early exploratory phase and/or have not resulted in the desired outcome, largely because photosynthesis is embedded within large networks of closely interacting cellular and metabolic processes, which can vary among species and even cultivars. This explains why integrated, systems-wide approaches are required to achieve the breakthroughs required for effectively increasing crop yields.

Automated summary

Photosynthesis is essential for life on Earth as it converts sunlight, water, and carbon dioxide into energy and oxygen. Increasing its efficiency is believed to be a promising approach to enhance crop yields. Various strategies, from targeting specific components to redesigning the entire process, have been proposed and partially tested. However, these efforts are still in the early stage and have not yet achieved the desired outcome due to the complex interactions among cellular and metabolic processes involved in photosynthesis.