Salt Stress Tolerance in Casuarina glauca and Its Relation with Nitrogen-Fixing Frankia Bacteria

Salinity is one of the most widespread abiotic stresses. It is estimated that salt stress will cause the loss of more than 50 % of arable land by the year 2050. A promising solution for the recovery of saline soils encompasses the use of actinorhizal plants, a group of perennial dicotyledonous angiosperms highly resilient to extreme environmental conditions. These plants are also able to establish a root nodule symbiosis with N2-fixing actinobacteria of the genus Frankia . Casuarina glauca , the model actinorhizal species, tolerates NaCl concentrations above seawater levels. Such ability seems to be innate and independent of the symbiotic relationship with N2-fixing Frankia. In this work, we present a mini review of the basic mechanisms underlying salt tolerance in C. glauca focusing on the impact of salt on the photosynthesis, redox status, and membrane integrity.