An integrated approach to understand the mechanisms underlying salt stress tolerance in Casuarina glauca and its relation with nitrogen-fixing Frankia Thr

Salinity is one of the most wide spread abiotic stresses affecting agricultural productivity, with an impact on more than 800 million hectares worldwide. A promising solution for the recovery of saline soils encompasses the use of actinorhizal plants, a group of perennial dicotyledonous angiosperms including species highly resilient to extreme environmental conditions. These plants are able to establish root-nodule symbiosis with N2-fixing actinobacteria of the genus Frankia. In this review, we discuss the main physiological and biochemical mechanisms underlying salt tolerance in the model Casuarina glauca supplemented with chemical nitrogen or obtaining it from symbiotic Frankia. In the first part, an overview of the impact of increasing NaCl concentrations in photosynthesis, antioxidative system and membrane integrity is presented. The second part addresses the effect of salt stress in the symbiosis between C. glauca and Frankia strain Thr. Preliminary results from analyses of the branchlets proteome and nodule metabolome are presented as well.