Plants use a chloroplast damage signal to fine-tune growth
Liu K, Wu W, Kim C
Plant Signaling
The sunburn-like stress that wilts your tomatoes on a scorching afternoon is being sensed and translated into a survival response by proteins scientists are only now learning to read, and that knowledge could lead to sturdier garden varieties down the road.
Inside every leaf's chloroplasts, sunlight can create a reactive, damaging form of oxygen as a byproduct of photosynthesis. Rather than just causing harm, plants use a pair of proteins called EXECUTER 1 and 2 to detect this reactive oxygen and turn it into a signal that tells the rest of the plant to adjust its growth and stress defenses, even affecting plants sitting in the dark. Researchers traced this sensing system back through plant evolution, finding simpler versions in green algae and the full system appearing later in early land plant ancestors, which helps explain how plants learned to cope with sunlight stress over millions of years.
Key Findings
EX1 protein undergoes oxidation and breakdown, and fragments of it interact with the TOC/TIC chloroplast protein-import machinery to trigger signaling cascades
EX1 has a previously unknown role in darkness, where it influences auxin-related gene networks that control plant growth
The full EXECUTER protein architecture (sensor domain plus UvrBC-like domain) first appeared in charophyte algae, while simpler sensor-only versions exist in earlier green algae lineages
chevron_right Technical Summary
Plants have a molecular warning system that senses light-triggered chemical damage in leaf chloroplasts and turns it into signals that adjust growth and stress responses. Scientists are now mapping how this system evolved and how it might be engineered to help crops handle stress better.
Abstract Preview
Original paper
EXECUTER-mediated singlet oxygen signaling in plants: Mechanisms, evolution, and functional diversification.
Singlet oxygen (1O2) is a highly reactive, chloroplast-derived reactive oxygen species that functions not only as a damaging oxidant but also as a signaling molecule regulating gene expression, str...
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