Spectral Radiation Dependent Photoprotective Mechanism in the Diatom Pseudo-nitzschia multistriata

Abstract

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.

The Velocity of Light Intensity Increase Modulates the Photoprotective Response in Coastal Diatoms

“…Fuco was the main accessory pigment, with its pool size being approximately ten- and seventeen-fold higher than that of Chl c 2 / c 3 and c 1 , respectively (Table 1). The presence of Chl c 3 , which is a pigment rarely found in diatoms, agrees with previous findings on the same species ([42] and references therein).…”

The color of mass culture: spectral characteristics of a shallow water column through shade‐limited algal growth dynamics1

“…, Brunet et al. ) that chloroplast photoreceptors monitor red and blue light fluence rates in order to regulate non‐photochemical quenching quenching (NPQ) in diatoms. Energy‐dependent quenching is the major photoprotective strategy in diatoms to avoid photoinhibition, and operates on timescales of seconds to minutes (Coesel et al.…”

“…Brunet et al. () found that XC for NPQ of diatoms required red light to be initiated and a high blue fluence rate to be activated. Their results (also see Schellenberger Costa et al.…”

Southern right whale (Eubalaena australis) calf mortality at Península Valdés, Argentina: Are harmful algal blooms to blame?

“…, Brunet et al . ), which would only produce 0.2–1 mg/m 3 chlorophyll for the abundances seen at PV.…”