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Fernández PA, Amsler CD, Hurd CL, Díaz PA, Gaitán-Espitia JD, Macaya EC, Schmider-Martínez A, Garrido I, Murúa P, Buschmann AH. Diverse inorganic carbon uptake strategies in Antarctic seaweeds: Revealing species-specific responses and implications for Ocean Acidification. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 945:174006. [PMID: 38889822 DOI: 10.1016/j.scitotenv.2024.174006] [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: 01/31/2024] [Revised: 05/09/2024] [Accepted: 06/13/2024] [Indexed: 06/20/2024]
Abstract
Seaweeds are important components of coastal benthic ecosystems along the Western Antarctic Peninsula (WAP), providing refuge, food, and habitat for numerous associated species. Despite their crucial role, the WAP is among the regions most affected by global climate change, potentially impacting the ecology and physiology of seaweeds. Elevated atmospheric CO2 concentrations have led to increased dissolved inorganic carbon (Ci) with consequent declines in oceanic pH and alterations in seawater carbonate chemistry, known as Ocean Acidification (OA). Seaweeds possess diverse strategies for Ci uptake, including CO2 concentrating mechanisms (CCMs), which may distinctly respond to changes in Ci concentrations. Conversely, some seaweeds do not operate CCMs (non-CCM species) and rely solely on CO2. Nevertheless, our understanding of the status and functionality of Ci uptake strategies in Antarctic seaweeds remains limited. Here, we investigated the Ci uptake strategies of seaweeds along a depth gradient in the WAP. Carbon isotope signatures (δ13C) and pH drift assays were used as indicators of the presence or absence of CCMs. Our results reveal variability in CCM occurrence among algal phyla and depths ranging from 0 to 20 m. However, this response was species specific. Among red seaweeds, the majority relied solely on CO2 as an exogenous Ci source, with a high percentage of non-CCM species. Green seaweeds exhibited depth-dependent variations in CCM status, with the proportion of non-CCM species increasing at greater depths. Conversely, brown seaweeds exhibited a higher prevalence of CCM species, even in deep waters, indicating the use of CO2 and HCO3-. Our results are similar to those observed in temperate and tropical regions, indicating that the potential impacts of OA on Antarctic seaweeds will be species specific. Additionally, OA may potentially increase the abundance of non-CCM species relative to those with CCMs.
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Affiliation(s)
- Pamela A Fernández
- Centro i∼mar, CeBiB & MASH, Universidad de Los Lagos, Camino a Chinquihue km6, Puerto Montt 580000, Chile.
| | - Charles D Amsler
- University of Alabama at Birmingham, Department of Biology, Birmingham, AL 35233, USA
| | - Catriona L Hurd
- Institute for marine and Antarctic Studies (IMAS), University of Tasmania, TAS 7001, Australia
| | - Patricio A Díaz
- Centro i∼mar, Universidad de Los Lagos, Camino a Chinquihue km6, Puerto Montt 580000, Chile
| | - Juan Diego Gaitán-Espitia
- The Swire Institute of Marine Science, School of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road, Hong Kong
| | - Erasmo C Macaya
- Departamento de Oceanografía, Universidad de Concepción, Concepción, Chile; Centro FONDAP de Investigación Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia 5090000, Chile
| | | | - Ignacio Garrido
- Centro FONDAP de Investigación Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia 5090000, Chile; Laboratorio Costero de Recursos Acuáticos de Calfuco (LCRAC), Instituto Ciencias Marinas y Limnológicas (ICML), Facultad de Ciencias, Universidad Austral de Chile, Valdivia 5110566, Chile; Department of Biology and Québec-Océan, Laval University, Québec, QC G1V 0A6, Canada
| | - Pedro Murúa
- Laboratorio de Macroalgas y Ficopatologia, Instituto de Acuicultura, Universidad Austral de Chile, Sede Puerto Montt, Puerto Montt, Chile
| | - Alejandro H Buschmann
- Centro i∼mar, CeBiB & MASH, Universidad de Los Lagos, Camino a Chinquihue km6, Puerto Montt 580000, Chile
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Capó-Bauçà S, Iñiguez C, Galmés J. The diversity and coevolution of Rubisco and CO 2 concentrating mechanisms in marine macrophytes. THE NEW PHYTOLOGIST 2024; 241:2353-2365. [PMID: 38197185 DOI: 10.1111/nph.19528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 12/15/2023] [Indexed: 01/11/2024]
Abstract
The kinetic properties of Rubisco, the most important carbon-fixing enzyme, have been assessed in a small fraction of the estimated existing biodiversity of photosynthetic organisms. Until recently, one of the most significant gaps of knowledge in Rubisco kinetics was marine macrophytes, an ecologically relevant group including brown (Ochrophyta), red (Rhodophyta) and green (Chlorophyta) macroalgae and seagrasses (Streptophyta). These organisms express various Rubisco types and predominantly possess CO2 -concentrating mechanisms (CCMs), which facilitate the use of bicarbonate for photosynthesis. Since bicarbonate is the most abundant form of dissolved inorganic carbon in seawater, CCMs allow marine macrophytes to overcome the slow gas diffusion and low CO2 availability in this environment. The present review aims to compile and integrate recent findings on the biochemical diversity of Rubisco and CCMs in the main groups of marine macrophytes. The Rubisco kinetic data provided demonstrate a more relaxed relationship among catalytic parameters than previously reported, uncovering a variability in Rubisco catalysis that has been hidden by a bias in the literature towards terrestrial vascular plants. The compiled data indicate the existence of convergent evolution between Rubisco and biophysical CCMs across the polyphyletic groups of marine macrophytes and suggest a potential role for oxygen in shaping such relationship.
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Affiliation(s)
- Sebastià Capó-Bauçà
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, 07122, Palma, Balearic Islands, Spain
| | - Concepción Iñiguez
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, 07122, Palma, Balearic Islands, Spain
- Department of Ecology, Faculty of Sciences, University of Malaga, Boulevard Louis Pasteur s/n, 29010, Málaga, Spain
| | - Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, 07122, Palma, Balearic Islands, Spain
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Aguiló-Nicolau P, Galmés J, Fais G, Capó-Bauçà S, Cao G, Iñiguez C. Singular adaptations in the carbon assimilation mechanism of the polyextremophile cyanobacterium Chroococcidiopsis thermalis. PHOTOSYNTHESIS RESEARCH 2023; 156:231-245. [PMID: 36941458 PMCID: PMC10154277 DOI: 10.1007/s11120-023-01008-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 02/16/2023] [Indexed: 05/03/2023]
Abstract
Cyanobacteria largely contribute to the biogeochemical carbon cycle fixing ~ 25% of the inorganic carbon on Earth. However, the carbon acquisition and assimilation mechanisms in Cyanobacteria are still underexplored regardless of being of great importance for shedding light on the origins of autotropism on Earth and providing new bioengineering tools for crop yield improvement. Here, we fully characterized these mechanisms from the polyextremophile cyanobacterium Chroococcidiopsis thermalis KOMAREK 1964/111 in comparison with the model cyanobacterial strain, Synechococcus sp. PCC6301. In particular, we analyzed the Rubisco kinetics along with the in vivo photosynthetic CO2 assimilation in response to external dissolved inorganic carbon, the effect of CO2 concentrating mechanism (CCM) inhibitors on net photosynthesis and the anatomical particularities of their carboxysomes when grown under either ambient air (0.04% CO2) or 2.5% CO2-enriched air. Our results show that Rubisco from C. thermalis possess the highest specificity factor and carboxylation efficiency ever reported for Cyanobacteria, which were accompanied by a highly effective CCM, concentrating CO2 around Rubisco more than 140-times the external CO2 levels, when grown under ambient CO2 conditions. Our findings provide new insights into the Rubisco kinetics of Cyanobacteria, suggesting that improved Sc/o values can still be compatible with a fast-catalyzing enzyme. The combination of Rubisco kinetics and CCM effectiveness in C. thermalis relative to other cyanobacterial species might indicate that the co-evolution between Rubisco and CCMs in Cyanobacteria is not as constrained as in other phylogenetic groups.
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Affiliation(s)
- Pere Aguiló-Nicolau
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears, INAGEA, Ctra. Valldemossa km. 7.5, 07122, Palma, Balearic Islands, Spain
| | - Jeroni Galmés
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears, INAGEA, Ctra. Valldemossa km. 7.5, 07122, Palma, Balearic Islands, Spain.
| | - Giacomo Fais
- Interdepartmental Centre of Environmental Science and Engineering, University of Cagliari, Via San Giorgio 12, 09124, Cagliari, Italy
| | - Sebastià Capó-Bauçà
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears, INAGEA, Ctra. Valldemossa km. 7.5, 07122, Palma, Balearic Islands, Spain
| | - Giacomo Cao
- Interdepartmental Centre of Environmental Science and Engineering, University of Cagliari, Via San Giorgio 12, 09124, Cagliari, Italy
- Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Via Marengo 2, 09123, Cagliari, Italy
| | - Concepción Iñiguez
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears, INAGEA, Ctra. Valldemossa km. 7.5, 07122, Palma, Balearic Islands, Spain
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