Arabidopsis species deploy distinct strategies to cope with drought stress

Little is known about how the physiological response to water deprivation differs among closely related plant species with different ecologies. In particular, how the relatives of the model species Arabidopsis thaliana react to drought stress is not known. We conducted a dry-down experiment that mimics a period of missing precipitation and monitors plant reactions to the progressive decrease in soil water content (SWC) in Arabidopsis thaliana, and its close relatives A. lyrata and A. halleri at phenotypic and transcriptomic levels. The three species differed in their reaction to decreasing soil water content. A. thaliana withstood low SWC but did not survive wilting. A. lyrata and A. halleri wilted at higher SWC but differed in water consumption rate and tolerance levels. Transcriptome data collected just before wilting and after recovery corroborated the phenotypic analysis, with A. halleri and A. lyrata showing a stronger activation of stress- and recovery-related genes, respectively. We conclude that these Arabidopsis species have evolved distinct strategies to face drought stress. A. lyrata employed both avoidance and tolerance mechanisms, whereas A. thaliana showed stronger avoidance reactions but no tolerance. A. halleri is the least able to protect itself from the stress imposed by drought.