The increase in soil salinization represents a current challenge for plant productivity, as most plants, including crops, are mainly salt-sensitive species. The identification of molecular traits underpinning salt tolerance represents a primary goal for breeding programs. In this scenario, the study of intraspecific variability represents a valid tool for investigating natural genetic resources evolved by plants in different environmental conditions. As a model system, Arabidopsis thaliana, including over 750 natural accessions, represents a species extensively studied at phenotypic, metabolic, and genomic levels under different environmental conditions. Two haplogroups showing opposite root architecture (shallow or deep roots) in response to auxin flux perturbation were identified and associated with EXO70A3 locus variations. Here, we studied the influence of these genetic backgrounds on plant salt tolerance. Eight accessions belonging to the two haplogroups were tested for salt sensitivity by exposing them to moderate (75 mM NaCl) or severe (150 mM NaCl) salt stress. Salt-tolerant accessions were found in both haplogroups, and all of them showed efficient ROS-scavenging ability. Even if an exclusive relation between salt tolerance and haplogroup membership was not observed, the modulation of root system architecture might also contribute to salt tolerance.
Keywords: Arabidopsis thaliana; biodiversity; reactive oxygen species; root system architecture; salinity.