Spectral radiation dependent photoprotective mechanism in the diatom Pseudo-nitzschia multistriata.
Phytoplankton, such as diatoms, experience great variations of photon flux density (PFD) and light spectrum along the marine water column. Diatoms have developed some rapidly-regulated photoprotective mechanisms, such as the xanthophyll cycle activation (XC) and the non-photochemical chlorophyll fluorescence quenching (NPQ), to protect themselves from photooxidative damages caused by excess PFD. In this study, we investigate the role of blue fluence rate in combination with red radiation in shaping photoacclimative and protective responses in the coastal diatom Pseudo-nitzschia multistriata. This diatom was acclimated to four spectral light conditions (blue, red, blue-red, blue-red-green), each of them provided with low and high PFD. Our results reveal that the increase in the XC pool size and the amplitude of NPQ is determined by the blue fluence rate experienced by cells, while cells require sensing red radiation to allow the development of these processes. Variations in the light spectrum and in the blue versus red radiation modulate either the photoprotective capacity, such as the activation of the diadinoxanthin-diatoxanthin xanthophyll cycle, the diadinoxanthin de-epoxidation rate and the capacity of non-photochemical quenching, or the pigment composition of this diatom. We propose that spectral composition of light has a key role on the ability of diatoms to finely balance light harvesting and photoprotective capacity.
Laboratory of Ecology and Evolution of Plankton, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy.
Christophe
C
Brunet
Laboratory of Ecology and Evolution of Plankton, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy.
Raghu
R
Chandrasekaran
Laboratory of Ecology and Evolution of Plankton, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy.
Lucia
L
Barra
Laboratory of Ecology and Evolution of Plankton, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy.
Vasco
V
Giovagnetti
Laboratory of Ecology and Evolution of Plankton, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy.
Federico
F
Corato
School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, United Kingdom.
Alexander V
AV
Ruban
D000064:Acclimatization / Q000502:physiology / Q000528:radiation effects*; D002734:Chlorophyll / Q000378:metabolism; D017377:Diatoms / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D017785:Photons; D010788:Photosynthesis / Q000502:physiology / Q000528:radiation effects; D010839:Phytoplankton / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D011827:Radiation; D024341:Xanthophylls / Q000378:metabolism
D024341:Xanthophylls; D002734:Chlorophyll; C033808:diadinoxanthin; C103105:diatoxanthin