The Role of Sustained Photoprotective Non-photochemical Quenching in Low Temperature and High Light Acclimation in the Bloom-Forming Arctic Diatom Thalassiosira gravida

• Published in: Frontiers in Marine Science
• Main Authors: Lacour, Thomas, Larivière, Jade, Ferland, Joannie, Bruyant, Flavienne, Lavaud, Johann, Babin, Marcel
• Other Authors: Takuvik Joint International Laboratory ULAVAL-CNRS, Université Laval Québec (ULaval)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: Arctic diatom; photosynthesis; sustained NPQ; irradiance; temperature; [SDE]Environmental Sciences; [SDV]Life Sciences [q-bio]; Arctic
• Online Access: https://hal.science/hal-02323707; https://hal.science/hal-02323707/document; https://hal.science/hal-02323707/file/2018e-FrontiersMarineSci.pdf; https://doi.org/10.3389/fmars.2018.00354

International audience Thalassiosira gravida is a major Arctic diatom responsible for the under-ice spring bloom. We investigated T. gravida physiological plasticity growing it at two temperatures (0 and 5 • C) and under different light intensities typically found in its natural environment. T. gravida showed remarkable thermal-and photo-acclimatory plasticity including: low light saturation parameter for growth (K E) and photosynthesis (E K), low µ max but relatively high Chl a/C, low C/N, and decreasing light-saturated carbon fixation rate (P C m) with increasing growth irradiance. T. gravida also showed remarkable photoprotective features, namely a strong sustained non-photochemical quenching (NPQs, hour kinetics relaxation) supported by a high amount of xanthophyll cycle pigments. T. gravida growth remained possible under a wide range of irradiances but photosynthetic plasticity was higher at moderately low light (up to ∼50 µmol photons m −2 s −1), nevertheless corresponding to the mean in situ conditions under which it predominates, i.e., underneath the spring thin-ice punctuated with melting ponds. The potential role of NPQs in the photophysiological plasticity of T. gravida is discussed.