Electrons Take Alternative Route to Prevent Plant Stress

Plants are susceptible to stress, and with the global impact of climate change and humanity’s growing demand for food, it’s crucial to understand what causes plant stress and stress tolerance. When plants absorb excess light energy during photosynthesis, reactive oxygen species are produced, potentially causing oxidative stress that damages important structures. Plants can suppress the production of reactive oxygen species by oxidizing P700 (the reaction center chlorophyll in photosystem I). A new study has revealed more about this vital process: the cyclic electron flow induced by P700 oxidation is an electric charge recombination occurring in photosystem I. These findings were published on June 5 in Plants.

The research was led by Professor Chikahiro Miyake, Assistant Professor Shinya Wada, and Kanae Kadota (Kobe University), in collaboration with Professor Amane Makino (Tohoku University) and Associate Professor Yuji Suzuki (Iwate University).

Professor Miyake’s team revealed in previous studies that all oxygen-producing photosynthetic species use the P700 oxidation system to deal with oxidative stress. Professor Miyake and Dr Giles Johnson (Senior Lecturer at the University of Manchester) discovered that P700 oxidation is accompanied by a cyclic electron flow (CEF) in photosystem I (PSI). This cyclic flow is not necessary for the linear electron flow that forms part of photosynthesis, so what is it doing? To find out more about this alternative flow, the team analyzed the interaction between the electron carriers linked to the reaction in the PSI complex and the PSII quantum yield [Y(II)] that evaluates the activity levels of the linear electron flow. They used a major crop: wheat leaves.

Read more at: Kobe University

Figure 1: Mechanism for reactive oxygen species creation in photosystem I (PSI) (Photo credit: Kobe University)