Cytochrome P450 CYP81D11 boosts CO2 assimilation and limits ROS damage under stress

Abstract

Chloroplasts are remarkable photosynthetic structures that fuel plants with energy-rich molecules, sustaining nearly all life on Earth. Yet, chloroplasts are also highly sensitive to environmental changes. For example, when water runs short or sunlight becomes too intense, the energy absorbed by photosynthetic pigments and its use in downstream photochemical reactions become imbalanced. This condition, known as photoinhibition, leads to the accumulation of damaging reactive oxygen species (ROS) that cause oxidative stress (Li and Kim 2022). Among ROS, singlet oxygen (1O2) is particularly dangerous. Unlike other ROS molecules, 1O2 is not formed by electron transfer. 1O2 is produced by direct energy transfer from chlorophyll or PSII reaction centers to oxygen, creating a reactive form that can damage many biomolecules in its vicinity. For example, peroxidation of lipids in thylakoid membranes by 1O2 can produce reactive carbonyl species (RCS) such as malondialdehyde and acrolein. Fortunately, plants have evolved strategies to prevent photoinhibition.