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Hüner NPA, Ivanov AG, Szyszka-Mroz B, Savitch LV, Smith DR, Kata V. Photostasis and photosynthetic adaptation to polar life. PHOTOSYNTHESIS RESEARCH 2024:10.1007/s11120-024-01104-7. [PMID: 38865029 DOI: 10.1007/s11120-024-01104-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 05/29/2024] [Indexed: 06/13/2024]
Abstract
Photostasis is the light-dependent maintenance of energy balance associated with cellular homeostasis in photoautotrophs. We review evidence that illustrates how photosynthetic adaptation in polar photoautrophs such as aquatic green algae, cyanobacteria, boreal conifers as well as terrestrial angiosperms exhibit an astonishing plasticity in structure and function of the photosynthetic apparatus. This plasticity contributes to the maintenance of photostasis, which is essential for the long-term survival in the seemingly inhospitable Antarctic and Arctic habitats. However, evidence indicates that polar photoautrophic species exhibit different functional solutions for the maintenance of photostasis. We suggest that this reflects, in part, the genetic diversity symbolized by inherent genetic redundancy characteristic of polar photoautotrophs which enhances their survival in a thermodynamically challenging environment.
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Affiliation(s)
- Norman P A Hüner
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, ON, N6A 3K7, Canada.
| | - Alexander G Ivanov
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, ON, N6A 3K7, Canada
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 21, Sofia, 1113, Bulgaria
| | - Beth Szyszka-Mroz
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, ON, N6A 3K7, Canada
| | - Leonid V Savitch
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, ON, K1A OC6, Canada
| | - David R Smith
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, ON, N6A 3K7, Canada
| | - Victoria Kata
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, ON, N6A 3K7, Canada
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Poirier M, Osmers P, Wilkins K, Morgan-Kiss RM, Cvetkovska M. Aberrant light sensing and motility in the green alga Chlamydomonas priscuii from the ice-covered Antarctic Lake Bonney. PLANT SIGNALING & BEHAVIOR 2023; 18:2184588. [PMID: 38126947 PMCID: PMC10012900 DOI: 10.1080/15592324.2023.2184588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 02/20/2023] [Indexed: 12/23/2023]
Abstract
The Antarctic green alga Chlamydomonas priscuii is an obligate psychrophile and an emerging model for photosynthetic adaptation to extreme conditions. Endemic to the ice-covered Lake Bonney, this alga thrives at highly unusual light conditions characterized by very low light irradiance (<15 μmol m-2 s-1), a narrow wavelength spectrum enriched in blue light, and an extreme photoperiod. Genome sequencing of C. priscuii exposed an unusually large genome, with hundreds of highly similar gene duplicates and expanded gene families, some of which could be aiding its survival in extreme conditions. In contrast to the described expansion in the genetic repertoire in C. priscuii, here we suggest that the gene family encoding for photoreceptors is reduced when compared to related green algae. This alga also possesses a very small eyespot and exhibits an aberrant phototactic response, compared to the model Chlamydomonas reinhardtii. We also investigated the genome and behavior of the closely related psychrophilic alga Chlamydomonas sp. ICE-MDV, that is found throughout the photic zone of Lake Bonney and is naturally exposed to higher light levels. Our analyses revealed a photoreceptor gene family and a robust phototactic response similar to those in the model Chlamydomonas reinhardtii. These results suggest that the aberrant phototactic response in C. priscuii is a result of life under extreme shading rather than a common feature of all psychrophilic algae. We discuss the implications of these results on the evolution and survival of shade adapted polar algae.
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Affiliation(s)
| | - Pomona Osmers
- Department of Biology, University of Ottawa, Ottawa, OH, Canada
| | - Kieran Wilkins
- Department of Biology, University of Ottawa, Ottawa, OH, Canada
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Cvetkovska M, Vakulenko G, Smith DR, Zhang X, Hüner NPA. Temperature stress in psychrophilic green microalgae: Minireview. PHYSIOLOGIA PLANTARUM 2022; 174:e13811. [PMID: 36309822 DOI: 10.1111/ppl.13811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 10/18/2022] [Accepted: 10/23/2022] [Indexed: 06/16/2023]
Abstract
Photosynthetic algae are the main primary producers in polar regions, form the basis of polar food webs, and are responsible for a significant portion of global carbon fixation. Many cold-water algae are psychrophiles that thrive in the cold but cannot grow at moderate temperatures (≥20°C). Polar regions are at risk of rapid warming caused by climate change, and the sensitivity of psychrophilic algae to rising temperatures makes them, and the ecosystems they inhabit, particularly vulnerable. Recent research on the Antarctic psychrophile Chlamydomonas priscuii, an emerging algal model, has revealed unique adaptations to life in the permanent cold. Additionally, genome sequencing of C. priscuii and its relative Chlamydomonas sp. ICE-L has given rise to a plethora of computational tools that can help elucidate the genetic basis of psychrophily. This minireview summarizes new advances in characterizing the heat stress responses in psychrophilic algae and examines their extraordinary sensitivity to temperature increases. Further research in this field will help determine the impact of climate change on psychrophiles from threatened polar environments.
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Affiliation(s)
- Marina Cvetkovska
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Galyna Vakulenko
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - David R Smith
- Department of Biology, University of Western Ontario, London, Canada
| | - Xi Zhang
- Institute for Comparative Genomics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
| | - Norman P A Hüner
- Department of Biology, University of Western Ontario, London, Canada
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Szyszka-Mroz B, Ivanov AG, Trick CG, Hüner NPA. Palmelloid formation in the Antarctic psychrophile, Chlamydomonas priscuii, is photoprotective. FRONTIERS IN PLANT SCIENCE 2022; 13:911035. [PMID: 36119589 PMCID: PMC9470844 DOI: 10.3389/fpls.2022.911035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 08/01/2022] [Indexed: 05/27/2023]
Abstract
Cultures of the obligate, Antarctic psychrophile, Chlamydomonas priscuii grown at permissive low temperature (8°C) are composed of flagellated, single cells, as well as non-motile, multicellular palmelloids. The relative proportions of the two cell types are temperature dependent. However, the temperature dependence for palmelloid formation is not restricted to psychrophilic C. priscuii but appears to be a general response of mesophilic Chlamydomonas species (C. reinhardtii and C. raudensis) to non-permissive growth temperatures. To examine potential differences in photosynthetic performance between single cells versus palmelloids of the psychrophile, a cell filtration technique was developed to separate single cells from palmelloids of C. priscuii grown at 8°C. Flow cytometry was used to estimate the diameter of isolated single cells (≤5 μm) versus isolated palmelloids of varying size (≥8 μm). Compared to single cells, palmelloids of C. priscuii showed a decrease in the abundance of light-harvesting complex II (LHCII) proteins with a 2-fold higher Chl a/b ratio. A decrease in both lutein and β-carotene in palmelloids resulted in carotenoid pools which were 27% lower in palmelloids compared to single cells of the psychrophile. Chlorophyll fluorescence analyses of the isolated fractions revealed that maximum photochemical efficiency of PSII (Fv/Fm) was comparable for both single cells and palmelloids of C. priscuii. However, isolated palmelloids exhibited lower excitation pressure, measured as 1 - qL, but higher yield of PSII (ΦPSII) and 50% higher rates of electron transport (ETR) than single cells exposed to high light at 8°C. This decreased sensitivity to high light in isolated palmelloids compared to single cells was associated with greater non-regulated dissipation of excess absorbed energy (ΦNO) with minimal differences in ΦNPQ in C. priscuii in response to increasing irradiance at low temperature. The ratio ΦNO/ΦNPQ observed for isolated palmelloids of C. priscuii developed at 8°C (1.414 ± 0.036) was 1.38-fold higher than ΦNO/ΦNPQ of isolated single cells (1.021 ± 0.018) exposed to low temperature combined with high light (1,000 μmol m-2 s-1). The differences in the energy quenching capacities between palmelloids and single cells are discussed in terms of enhanced photoprotection of C. priscuii palmelloids against low-temperature photoinhibition.
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Affiliation(s)
- Beth Szyszka-Mroz
- Department of Biology and the Biotron Centre for Experimental Climate Change Research, University of Western Ontario, London, ON, Canada
| | - Alexander G. Ivanov
- Department of Biology and the Biotron Centre for Experimental Climate Change Research, University of Western Ontario, London, ON, Canada
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Charles G. Trick
- School of Public Health, University of Saskatchewan, Saskatoon, SK, Canada
| | - Norman P. A. Hüner
- Department of Biology and the Biotron Centre for Experimental Climate Change Research, University of Western Ontario, London, ON, Canada
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