A Pollen Carbonic Anhydrase Promotes Male Fertility Under Elevated Carbon Dioxide in Tomato

Rising atmospheric CO₂ is a defining feature of climate change and profoundly influences plant growth and productivity. While the effects of elevated CO₂ on photosynthesis and vegetative biomass have been extensively studied, its direct impact on male reproductive development remains poorly understood. Here, we show that elevated CO₂ improves pollen vigour and performance in tomato (Solanum lycopersicum). Through genetic and molecular analyses, we identify β-type carbonic anhydrase 2 (βCA2) as a pollen-enriched CO₂ sensor required for this response. Loss of βCA2 abolishes the promoting effects of elevated CO₂ on fertility, whereas βCA2 overexpression mimics the high-CO₂ phenotype under ambient conditions. Further analyses revealed that βCA2 regulates downstream networks involved in vesicle trafficking and intracellular transport to promote pollen germination, alongside cellulose and pectin metabolism required for pollen intine remodelling. These findings suggest a potential link between βCA2-mediated CO₂ perception, intracellular transport and pollen intine remodelling. Our results uncover a dynamic, pollen-specific CO₂ response pathway that integrates intracellular transport with structural wall remodelling, providing new insights into how plants sustain male fertility under rising atmospheric CO₂.