Poster - International Plant System Biology workshop

Climate change comes as a major challenge in agroecology, notably through the sustained rise of atmospheric CO2 levels. Field studies conducted worldwide have shown that exposure to elevated CO2 leads to a marked depletion in the content of most nutrients in crops, deteriorating their nutritional value and representing a serious threat to human health. Literature suggests that even though biomass is increased by elevated CO2, the observed mineral depletion is not only due to carbon dilution, but also to negative perturbations on nutritional signaling pathways. However, most of the regulatory mechanisms causing a negative effect on plant mineral nutrition under elevated CO2 remain to be identified. Therefore, in order to preserve food security for the future in a context of sustainable agriculture with low inputs, it is crucial to understand how elevated CO2 impacts regulatory circuits associated with plant mineral nutrition.

For this purpose we generated transcriptomic datasets in which Arabidopsis plants were exposed to elevated CO2, low nitrate conditions and iron starvation in a combinatorial fashion. We used it first to investigate how gene expression is being reprogrammed in roots under high atmospheric CO2, and how this response interacts with nutritional starvation pathways. We notably show that elevated CO2 significantly disrupts signaling pathways associated with nitrate and iron starvations.

Then, we reconstructed a genome-wide network of candidate regulatory interactions of the response to elevated CO2 under low nitrate. We made use of Random Forests, a machine learning approach allowing the extraction of candidate regulatory links between regulators and genes, based on their expression profiles. We developed a statistical procedure to refine this output into a sparse network by empirical tests on the inferred gene pairs. This approach led us to identify several potential regulators of plant response to nutritional limitations under elevated CO2, of which we are currently characterizing the role.

Altogether, our results indicate that elevated CO2 alters plant response to nutrient starvation, by deregulating nutrient uptake adaptive strategies in roots. This finding, along with the identification of candidate genes from network analysis pave the way for strategies aiming at maintaining plant nutritional value despite the progression of climate change, in a sustainable perspective.