Diatom phytochromes reveal the existence of far-red-light-based sensing in the ocean
Fortunato, A.E.; Jaubert, M.; Enomoto, G.; Bouly, J.-P.; Raniello, R.; Thaler, M.; Malviya, S.; Bernardes, J.S.; Rappaport, F.; Gentili, B.; Huysman, M.J.J.; Carbone, A.; Bowler, C.; d'Alcalà, M.R.; Ikeuchi, M.; Falciatore, A. (2016). Diatom phytochromes reveal the existence of far-red-light-based sensing in the ocean. Plant Cell 28(3): 616-628. https://dx.doi.org/10.1105/tpc.15.00928 In: The Plant Cell. American Society of Plant Biologists: Rockville, MD. ISSN 1040-4651; e-ISSN 1532-298X, more |   |
| Authors | | Top | - Fortunato, A.E.
- Jaubert, M.
- Enomoto, G.
- Bouly, J.-P.
- Raniello, R.
- Thaler, M.
| - Malviya, S.
- Bernardes, J.S.
- Rappaport, F.
- Gentili, B.
- Huysman, M.J.J., more
| - Carbone, A.
- Bowler, C.
- d'Alcalà, M.R.
- Ikeuchi, M.
- Falciatore, A.
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| Abstract | The absorption of visible light in aquatic environments has led to the common assumption that aquatic organisms sense and adapt to penetrative blue/green light wavelengths but show little or no response to the more attenuated red/far-red wavelengths. Here, we show that two marine diatom species, Phaeodactylum tricornutum and Thalassiosira pseudonana, possess a bona fide red/far-red light sensing phytochrome (DPH) that uses biliverdin as a chromophore and displays accentuated red-shifted absorbance peaks compared with other characterized plant and algal phytochromes. Exposure to both red and far-red light causes changes in gene expression in P. tricornutum, and the responses to far-red light disappear in DPH knockout cells, demonstrating that P. tricornutum DPH mediates far-red light signaling. The identification of DPH genes in diverse diatom species widely distributed along the water column further emphasizes the ecological significance of far-red light sensing, raising questions about the sources of far-red light. Our analyses indicate that, although far-red wavelengths from sunlight are only detectable at the ocean surface, chlorophyll fluorescence and Raman scattering can generate red/far-red photons in deeper layers. This study opens up novel perspectives on phytochrome-mediated far-red light signaling in the ocean and on the light sensing and adaptive capabilities of marine phototrophs. |
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