A gene regulatory network in Arabidopsis roots reveals features and regulators of the plant response to elevated CO2.

The elevation of CO2 in the atmosphere increases plant biomass but decreases their mineral content. The genetic and molecular bases of these effects remain mostly unknown, in particular in the root system, which is responsible for plant nutrient uptake. To gain knowledge about the effect of elevated CO2 on plant growth and physiology, and to identify its regulatory in the roots, we analyzed genome expression in Arabidopsis roots through a combinatorial design with contrasted levels of CO2 , nitrate, and iron. We demonstrated that elevated CO2 has a modest effect on root genome expression under nutrient sufficiency, but by contrast leads to massive expression changes under nitrate or iron deficiencies. We demonstrated that elevated CO2 negatively targets nitrate and iron starvation modules at the transcriptional level, associated with a reduction in high-affinity nitrate uptake. Finally, we inferred a gene regulatory network governing the root response to elevated CO2 . This network allowed us to identify candidate transcription factors including MYB15, WOX11, and EDF3 which we experimentally validated for their role in the stimulation of growth by elevated CO2 . Our approach identified key features and regulators of the plant response to elevated CO2 , with the objective of developing crops resilient to climate change.