Comparative Analysis of the Antioxidant Response to Salt Stress in Inula crithmoides and Dittrichia viscosa

Salt stress, as well as other abiotic stresses, induces the activation of antioxidant systems in plants, since they cause oxidative stress as a secondary effect. We have analysed the antioxidant response to salt treatments of two related species, Inula crithmoides and Dittrichia viscosa, in terms of accumulation of total phenolic compounds and flavonoids. The most salt-tolerant species, I. crithmoides, was less affected than D. viscosa by oxidative stress in the presence of high NaCl concentrations, as revealed by its relatively lower contents of malondialdehyde, a reliable oxidative stress biomarker. Consequently, salt-induced accumulation of antioxidant phenolics and flavonoids was much lower in I. crithomoides, as compared to D. viscosa. From these data, we concluded that the higher salt tolerance of I. crithomoides cannot be based in the activation of stronger antioxidant systems, but must be due to other stress responses -such as the control of water and ion transport and the synthesis of osmolytes for cellular osmotic balance.