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A Constitutive Stress Response is an Adaptation to Low Temperature in the Antarctic green alga Chlamydomonas sp. UWO241
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  • Marina Cvetkovska,
  • Xi Zhang,
  • Galyna Vakulenko,
  • Samuel Benzaquen,
  • Beth Szyszka-Mroz,
  • Nina Malczewski,
  • David Smith,
  • Norman P. A. Huner
Marina Cvetkovska
University of Ottawa
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Xi Zhang
University of Western Ontario
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Galyna Vakulenko
University of Ottawa
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Samuel Benzaquen
University of Ottawa
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Beth Szyszka-Mroz
University of Western Ontario
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Nina Malczewski
University of Western Ontario
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David Smith
University of Western Ontario
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Norman P. A. Huner
University of Western Ontario
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Abstract

The Antarctic green alga Chlamydomonas sp. UWO241 is an obligate psychrophile that thrives in the cold (4-6°C) but is unable to survive at temperatures ≥18°C. Little is known how exposure to heat affects its physiology or whether it mounts a heat stress response in a manner comparable to mesophiles. Here, we dissect the responses of UWO241 to temperature stress by examining its growth, primary metabolome and transcriptome under steady-state low temperature and heat stress conditions. In comparison with Chlamydomonas reinhardtii, UWO241 constitutively accumulates metabolites and proteins commonly considered as stress markers, including soluble sugars, antioxidants, polyamines, and heat shock proteins to ensure efficient protein folding at low temperatures. We propose that this permanent stress metabolism is an adaptive advantage to life at extreme conditions. A shift from 4°C to a non-permissive temperature of 24°C alters the UWO241 primary metabolome and transcriptome, but growth of UWO241 at higher permissive temperatures (10°C and 15°C) does not provide enhanced heat protection. UWO241 also fails to induce the accumulation of HSPs when exposed to heat, suggesting that it has lost the ability to fine-tune its heat stress response. Our work adds to the growing body of research on temperature stress in psychrophiles, many of which are threatened by climate change.

Peer review status:ACCEPTED

13 Jul 2021Submitted to Plant, Cell & Environment
14 Jul 2021Submission Checks Completed
14 Jul 2021Assigned to Editor
16 Jul 2021Reviewer(s) Assigned
09 Aug 2021Review(s) Completed, Editorial Evaluation Pending
16 Aug 2021Editorial Decision: Revise Minor
25 Aug 20211st Revision Received
26 Aug 2021Submission Checks Completed
26 Aug 2021Assigned to Editor
28 Aug 2021Review(s) Completed, Editorial Evaluation Pending
28 Aug 2021Editorial Decision: Accept