Salt stress tolerance in Casuarina glauca and its relation with nitrogen-fixing Frankia bacteria

Abstract

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.