Abstract
Calcareous soils, characterised by high soil calcium carbonate (CaCO3) content and alkaline pH, are often found in (semi-)arid areas such as the Mediterranean basin. Furthermore, these regions are particularly exposed to high average annual temperature, which is expected to steadily increase in the future decades. The impact of temperature increase on plant performance growing in calcareous soil is unknown. The large geographical and genetic diversity of the model plant Arabidopsis thaliana is suitable to decipher the genetic bases involved in their adaptation to calcareous soil in the context of increasing temperatures. We selected European accessions from the 1001 Genomes project and from natural accessions collected in the Pyrénées mountains to characterise their tolerance to CaCO3, temperature increase and a combination of both stresses. We found that increased temperature stimulated biomass production and reshaped the correlation spectrum in a way that more accessions better tolerate CaCO3. Genome-wide transcriptomic analyses performed on accessions with contrasted tolerance to CaCO3 and high temperature revealed deviations of expression in different metabolic pathways. Furthermore, a genome-wide association study (GWAS) approach identified potential candidate genes to regulate adaptation to CaCO3 and high temperature. In fine, we aim to transpose our findings to the crop species Durum wheat to promote the selection or the development of better adapted genotypes to calcareous soils.