Effects of excess light energy on excitation-energy dynamics in a pennate diatom Phaeodactylum tricornutum

Ryo Nagao, Yoshifumi Ueno, Makio Yokono, Jian-Ren Shen, Seiji Akimoto

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Controlling excitation energy flow is a fundamental ability of photosynthetic organisms to keep a better performance of photosynthesis. Among the organisms, diatoms have unique light-harvesting complexes, fucoxanthin chlorophyll (Chl) a/c-binding proteins. We have recently investigated light-adaptation mechanisms of a marine centric diatom, Chaetoceros gracilis, by spectroscopic techniques. However, it remains unclear how pennate diatoms regulate excitation energy under different growth light conditions. Here, we studied light-adaptation mechanisms in a marine pennate diatom Phaeodactylum tricornutum grown at 30 µmol photons m −2  s −1 and further incubated for 24 h either in the dark, or at 30 or 300 µmol photons m −2  s −1 light intensity, by time-resolved fluorescence (TRF) spectroscopy. The high-light incubated cells showed no detectable oxygen-evolving activity of photosystem II, indicating the occurrence of a severe photodamage. The photodamaged cells showed alterations of steady-state absorption and fluorescence spectra and TRF spectra compared with the dark and low-light adapted cells. In particular, excitation-energy quenching is significantly accelerated in the photodamaged cells as shown by mean lifetime analysis of the Chl fluorescence. These spectral changes by the high-light treatment may result from arrangements of pigment–protein complexes to maintain the photosynthetic performance under excess light illumination. These growth-light dependent spectral properties in P. tricornutum are largely different from those in C. gracilis, thus providing insights into the different light-adaptation mechanisms between the pennate and centric diatoms.

Original languageEnglish
JournalPhotosynthesis research
DOIs
Publication statusPublished - Jan 1 2019

Fingerprint

Diatoms
Phaeodactylum tricornutum
Bacillariophyceae
Excitation energy
Light
energy
Ocular Adaptation
Chaetoceros gracilis
Fluorescence
Photons
fluorescence
fluorescence emission spectroscopy
Chlorophyll Binding Proteins
cells
Photosystem II Protein Complex
chlorophyll
Fluorescence Spectrometry
Photosynthesis
Chlorophyll
light harvesting complex

Keywords

  • FCP
  • Low-energy Chl
  • Pennate diatom
  • Photoinhibition
  • Time-resolved fluorescence spectroscopy

ASJC Scopus subject areas

  • Biochemistry
  • Plant Science
  • Cell Biology

Cite this

Effects of excess light energy on excitation-energy dynamics in a pennate diatom Phaeodactylum tricornutum. / Nagao, Ryo; Ueno, Yoshifumi; Yokono, Makio; Shen, Jian-Ren; Akimoto, Seiji.

In: Photosynthesis research, 01.01.2019.

Research output: Contribution to journalArticle

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