Differential functional traits underlying the contrasting salt tolerance in Lepidium species

To explore the mechanisms responsible for salt tolerance in Brassicaceae species, a multifactorial approach was used to clarify the functional traits underlying the differential salt tolerance in two Lepidium species, namely the halophyte L. latifolium and its glycophyte relative, L. sativum. Parameters related to photosynthesis, nitrogen assimilation, ion accumulation, water relations and succulence, osmotic adjustment, phenolics metabolism, antioxidative defense, nitric oxide (NO) level and the expression of Na+ antiporter (SOS1 and NHX) were analyzed in plants grown under salt stress in hydroponics. In addition to significant differences regarding the majority of salt tolerance indicators, a characteristic early boost, 52 h after exposure to salt, was observed in the concentration of H2O2 and NO in the halophyte, which was almost absent in the glycophyte. Following the application of detrended component analysis, discrimination between the glycophyte and halophyte could only be performed via temporal curves in the antioxdative components and NO, and less effectively, by phenolics metabolism. H2O2 and NO signaling and the adaptive modification of phenolics metabolism play crucial roles in determining the halophytic behavior of L. latifolium. These data may result in new insights concerning the studies on halophytism in the Brassicaceae.