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Plant Cell. 2016 Mar;28(3):616-28. doi: 10.1105/tpc.15.00928. Epub 2016 Mar 3.

Diatom Phytochromes Reveal the Existence of Far-Red-Light-Based Sensing in the Ocean.

Author information

1
Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France.
2
Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo 153-8902, Japan.
3
Stazione Zoologica Anton Dohrn, 80121 Naples, Italy.
4
Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure, CNRS UMR 8197, INSERM U1024, F-75005 Paris, France.
5
Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 75005 Paris, France.
6
Sorbonne Universités, UPMC Univ-Paris 6, CNRS, UMR 7093, Laboratoire d'Océanologie de Villefranche, F-06230 Villefranche/mer, France.
7
Protistology and Aquatic Ecology, Department of Biology, Ghent University, B-9000 Gent, Belgium Department of Plant Systems Biology, VIB, B-9052 Gent, Belgium Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Gent, Belgium.
8
Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France Institut Universitaire de France, 75005 Paris, France.
9
Stazione Zoologica Anton Dohrn, 80121 Naples, Italy maurizio@szn.it angela.falciatore@upmc.fr.
10
Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative UMR 7238, 75006 Paris, France maurizio@szn.it angela.falciatore@upmc.fr.

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.

PMID:
26941092
PMCID:
PMC4826011
DOI:
10.1105/tpc.15.00928
[Indexed for MEDLINE]
Free PMC Article

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