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Phototropin can trigger the chloroplast accumulation response from multiple subcellular locations in Marchantia
Mayu Hanawa1, Satoyuki Hirano1, Kotoko Sasaki1
1Center for Bioscience Research and Education, Utsunomiya University, Tochigi, 321-8505, Japan; Graduate School of Regional Development and Creativity, Utsunomiya University, Tochigi, 321-8505, Japan.
Biochemical and Biophysical Research Communications
|April 3, 2026
Summary
Chloroplasts move to maximize light capture and avoid damage, a process mediated by phototropin. Different cellular locations of phototropin (pm-phot, cy-phot, cp-phot) show spatial redundancy for light accumulation responses in Marchantia polymorpha.
Area of Science:
- Plant cell biology
- Photobiology
- Molecular genetics
Background:
- Chloroplasts exhibit phototaxis, moving to optimize light absorption for photosynthesis and prevent photodamage.
- Phototropin, a blue-light receptor, is known to mediate these chloroplast movements.
- The precise subcellular localization of phototropin responsible for mediating these responses has remained unclear.
Purpose of the Study:
- To investigate which subcellular pool of phototropin mediates chloroplast relocation in response to light.
- To compare the functions of phototropin localized to the plasma membrane, cytosol, and chloroplast outer membrane.
Main Methods:
- Generated transgenic Marchantia polymorpha lines with phototropin targeted to the plasma membrane (pm-phot), cytosol (cy-phot), or chloroplast outer membrane (cp-phot) in a phototropin-knockout background.
- Compared chloroplast accumulation and avoidance responses among these transgenic lines.
- Quantified chloroplast behavior and signal transfer rates to assess response efficiency.
Main Results:
- The avoidance response was mediated exclusively by plasma membrane-localized phototropin (pm-phot).
- All tested phototropin localization variants (pm-phot, cy-phot, cp-phot) successfully mediated the chloroplast accumulation response.
- Accumulation response efficiency, including chloroplast behavior and signal transfer, was comparable across all variants.
Conclusions:
- Phototropin exhibits spatial redundancy in mediating the chloroplast accumulation response in Marchantia polymorpha.
- While plasma membrane localization is crucial for the avoidance response, other cellular compartments can trigger accumulation.
- This study elucidates the distinct roles of phototropin localization in mediating different types of chloroplast phototaxis.
Keywords:
Accumulation responseBryophyteChloroplast movementMarchantia polymorphaPhototropinSubcellular localizationMore Related Videos
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