Plant Nutrient Homeostasis In A Rising CO2 World

The rapid rise in atmospheric CO2 concentration presents a critical paradox for global agriculture: while it stimulates photosynthesis and plant productivity, it simultaneously compromises crop nutritional quality. This decline in quality is linked to a lower concentration of essential macro- and micronutrients in crop edible parts, involving complex regulatory shifts that go beyond the simple growth dilution effect caused by the decoupling between growth and nutrient uptake. In this review, we summarize the current knowledge regarding the impact of elevated CO2 (eCO2) on nitrogen (N) nutrition, among other aspects, discussing how the availability of nitrate (NO3-) or ammonium (NH4+) affects plant growth and N status under eCO2, a long-standing debate in the field. We outline recent advances in the signalling mechanisms regulating NO3- uptake under eCO2 and discuss the interaction between photorespiration and the assimilation of both N sources. Likewise, we address the main effects and regulatory mechanisms associated with eCO2 and the homeostasis of sulphur (S), phosphorus (P) and the micronutrients iron (Fe) and zinc (Zn). Collectively, we intend to provide a comprehensive framework to guide future crop breeding and climate-resilient agronomic management.