The desert green algae Chlorella ohadii thrives at excessively high light intensities by exceptionally enhancing the mechanisms that protect photosynthesis from photoinhibition

Guy Levin, Sharon Kulikovsky, Varda Liveanu, Benjamin Eichenbaum, Ayala Meir, Tal Isaacson, Yaakov Tadmor, Noam Adir, Gadi Schuster

Research output: Contribution to journalArticlepeer-review

Abstract

Although light is the driving force of photosynthesis, excessive light can be harmful. One of the main processes that limits photosynthesis is photoinhibition, the process of light-induced photodamage. When the absorbed light exceeds the amount that is dissipated by photosynthetic electron flow and other processes, damaging radicals are formed that mostly inactivate photosystem II (PSII). Damaged PSII must be replaced by a newly repaired complex in order to preserve full photosynthetic activity. Chlorella ohadii is a green microalga, isolated from biological desert soil crusts, that thrives under extreme high light and is highly resistant to photoinhibition. Therefore, C. ohadii is an ideal model for studying the molecular mechanisms underlying protection against photoinhibition. Comparison of the thylakoids of C. ohadii cells that were grown under low light versus extreme high light intensities found that the alga employs all three known photoinhibition protection mechanisms: (i) massive reduction of the PSII antenna size; (ii) accumulation of protective carotenoids; and (iii) very rapid repair of photodamaged reaction center proteins. This work elucidated the molecular mechanisms of photoinhibition resistance in one of the most light-tolerant photosynthetic organisms, and shows how photoinhibition protection mechanisms evolved to marginal conditions, enabling photosynthesis-dependent life in severe habitats.

Original languageEnglish
Pages (from-to)1260-1277
Number of pages18
JournalPlant Journal
Volume106
Issue number5
DOIs
StatePublished - Jun 2021
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2021 Society for Experimental Biology and John Wiley & Sons Ltd

Keywords

  • chlorella
  • D1 turnover
  • green algae
  • photoinhibition
  • photoprotection
  • photosynthetic antenna size
  • xanthophyll cycle

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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