Diurnal fluctuations in chloroplast GSH redox state regulate susceptibility to oxidative stress and cell fate in a bloom-forming diatom

Adi Volpert, Shiri Graff van Creveld, Shilo Rosenwasser, Assaf Vardi

Research output: Contribution to journalArticlepeer-review


Diatoms are one of the key phytoplankton groups in the ocean, forming vast oceanic blooms and playing a significant part in global primary production. To shed light on the role of redox metabolism in diatom's acclimation to light–dark transition and its interplay with cell fate regulation, we generated transgenic lines of the diatom Thalassiosira pseudonana that express the redox-sensitive green fluorescent protein targeted to various subcellular organelles. We detected organelle-specific redox patterns in response to oxidative stress, indicating compartmentalized antioxidant capacities. Monitoring the GSH redox potential (EGSH) in the chloroplast over diurnal cycles revealed distinct rhythmic patterns. Intriguingly, in the dark, cells exhibited reduced basal chloroplast EGSH but higher sensitivity to oxidative stress than cells in the light. This dark-dependent sensitivity to oxidative stress was a result of a depleted pool of reduced glutathione which accumulated during the light period. Interestingly, reduction in the chloroplast EGSH was observed in the light phase prior to the transition to darkness, suggesting an anticipatory phase. Rapid chloroplast EGSH re-oxidation was observed upon re-illumination, signifying an induction of an oxidative signaling during transition to light that may regulate downstream metabolic processes. Since light–dark transitions can dictate metabolic capabilities and susceptibility to a range of environmental stress conditions, deepening our understanding of the molecular components mediating the light-dependent redox signals may provide novel insights into cell fate regulation and its impact on oceanic bloom successions.

Original languageEnglish
Pages (from-to)329-341
Number of pages13
JournalJournal of Phycology
Issue number3
StatePublished - Jun 2018


  • PCD
  • ROS
  • Thalassiosira pseudonana
  • diatoms
  • diurnal cycles
  • redox signaling

All Science Journal Classification (ASJC) codes

  • Aquatic Science
  • Plant Science


Dive into the research topics of 'Diurnal fluctuations in chloroplast GSH redox state regulate susceptibility to oxidative stress and cell fate in a bloom-forming diatom'. Together they form a unique fingerprint.

Cite this