Processes independent of nonphotochemical quenching protect a high-light-tolerant desert alga from oxidative stress

Plant Physiol. 2024 Dec 23;197(1):kiae608. doi: 10.1093/plphys/kiae608.

Abstract

Nonphotochemical quenching (NPQ) mechanisms are crucial for protecting photosynthesis from photoinhibition in plants, algae, and cyanobacteria, and their modulation is a long-standing goal for improving photosynthesis and crop yields. The current work demonstrates that Chlorella ohadii, a green microalga that thrives in the desert under high light intensities that are fatal to many photosynthetic organisms does not perform nor require NPQ to protect photosynthesis under constant high light. Instead of dissipating excess energy, it minimizes its uptake by eliminating the photosynthetic antenna of photosystem II. In addition, it accumulates antioxidants that neutralize harmful reactive oxygen species (ROS) and increases cyclic electron flow around PSI. These NPQ-independent responses proved efficient in preventing ROS accumulation and reducing oxidative damage to proteins in high-light-grown cells.

MeSH terms

  • Antioxidants / metabolism
  • Chlorella* / drug effects
  • Chlorella* / metabolism
  • Chlorella* / physiology
  • Chlorella* / radiation effects
  • Chlorophyll / metabolism
  • Desert Climate
  • Electron Transport / drug effects
  • Electron Transport / radiation effects
  • Light*
  • Oxidative Stress*
  • Photosynthesis*
  • Photosystem I Protein Complex / metabolism
  • Photosystem II Protein Complex* / metabolism
  • Reactive Oxygen Species* / metabolism

Substances

  • Reactive Oxygen Species
  • Photosystem II Protein Complex
  • Antioxidants
  • Photosystem I Protein Complex
  • Chlorophyll