Carbonic Anhydrase Functions in Plant Physiology

Carbonic anhydrases (CAs) are zinc-dependent metalloenzymes that catalyse the reversible hydration of carbon dioxide to bicarbonate, a reaction central to numerous physiological processes in plants. Distinct families of CAs (α, β and γ) comprise multiple isoforms that localise to chloroplast stroma, thylakoid membranes, cytosol, mitochondria and cell walls, reflecting a finely tuned subcellular architecture. In photosynthetic tissues, CAs facilitate rapid delivery of CO₂ to ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), thereby enhancing carboxylation rates and reducing photorespiratory losses. They also contribute to pH regulation by buffering proton flux during light-driven electron transport and support stomatal movements via CO₂/HCO₃⁻ sensing mechanisms. In C₄ and crassulacean acid metabolism (CAM) species, specialised CA isoforms underpin carbon-concentrating mechanisms that boost water-use efficiency and carbon assimilation under low CO₂ or arid conditions. Beyond photosynthesis, CAs in root tissues participate in nutrient acquisition by modulating rhizosphere pH and may influence nodulation and nitrogen fixation in legumes. Genetic manipulation of CA expression has demonstrated potential for improving crop yield under elevated or subambient CO₂, offering a promising avenue to mitigate the impacts of climate change on global agriculture.

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Carbonic Anhydrase Functions in Plant Physiology publication trend

The graph below shows the total number of articles in carbonic anhydrase functions in plant physiology across all publications each year (not limited to Nature Index journals).

Technical terms

Carbonic anhydrase (CA): A zinc-containing enzyme that catalyses the interconversion of CO₂ and HCO₃⁻, critical for photosynthesis and pH regulation.

Isoform: A variant of a protein arising from gene duplication or alternative splicing, often with distinct localisation or function.

Thylakoid: A membrane-bound compartment within chloroplasts where the light-dependent reactions of photosynthesis occur.

Photosystem: A complex of proteins and pigments (PSI or PSII) involved in capturing light energy and driving electron transport.

Bicarbonate (HCO₃⁻): The hydrated form of CO₂ in aqueous environments, serving as a substrate for CAs and influencing cellular pH.

References

1. Plant Carbonic Anhydrases: Structures, Locations, Evolution, and Physiological Roles. Molecular Plant (2016).
2. Carbonic anhydrases in the cell wall and plasma membrane of Arabidopsis thaliana are required for optimal plant growth on low CO2. Frontiers in Molecular Biosciences (2024).
3. Features of Photosynthesis in Arabidopsis thaliana Plants with Knocked Out Gene of Alpha Carbonic Anhydrase 2. Plants (2023).
4. Alpha Carbonic Anhydrase 5 Mediates Stimulation of ATP Synthesis by Bicarbonate in Isolated Arabidopsis Thylakoids. Frontiers in Plant Science (2021).
5. Molecular Characterization of Carbonic Anhydrase Genes in Lotus japonicus and Their Potential Roles in Symbiotic Nitrogen Fixation. International Journal of Molecular Sciences (2021).