Plant growth stimulation by high CO₂ depends on phosphorus homeostasis in chloroplasts

Elevated atmospheric CO₂ enhances photosynthetic rate,¹ thereby increasing biomass production in plants. Nevertheless, high CO₂ reduces the accumulation of essential nutrients² such as phosphorus (P),³ which are required for photosynthetic processes and plant growth. How plants ensure enhanced growth despite meager P status remains enigmatic. In this study, we utilize genome-wide association analysis in Arabidopsis thaliana to identify a P transporter, PHT4;3, which mediates the reduction of P in chloroplasts at high CO₂. Decreasing chloroplastic P fine-tunes the accumulation of a sugar-P metabolite, phytic acid, to support plant growth. Furthermore, we demonstrate that this adaptive mechanism is conserved in rice. Our results establish a mechanistic framework for sustainable food production against the backdrop of soaring CO₂ levels across the world.