The elevation of atmospheric CO 2 concentration has a strong impact on the physiology of C3 plants, far beyond photosynthesis and C metabolism. In particular, it reduces the concentrations of most mineral nutrients in plant tissues, posing major threats on crop quality, nutrient cycles, and carbon sinks in terrestrial agro-ecosystems. The causes of the detrimental effect of high CO 2 levels on plant mineral status are not understood. We provide an update on the main hypotheses and review the increasing evidence that, for nitrogen, this detrimental effect is associated with direct inhibition of key mechanisms of nitrogen uptake and assimilation. We also mention promising strategies for identifying genotypes that will maintain robust nutrient status in a future high-CO 2 world. Elevated [CO 2 ] (eCO 2) has a negative impact on key physiological mechanisms of nutrient acquisition and assimilation in C3 plants. The reasons are largely unknown. eCO 2 particularly lowers nitrogen content of plants tissues, possibly through specific inhibition of nitrate uptake and assimilation. The altered nutrient status of plants grown at eCO 2 is one likely cause of the acclimation of photosynthesis to eCO 2 that prevents full stimulation of biomass production in response to 'CO 2 fertilization'. The high natural genetic variability of the eCO 2 impact on plant nutrient status can be exploited as a promising strategy to breed future crops better adapted to a high-CO 2 world. [ABSTRACT FROM AUTHOR]