Salicylic acid increases drought adaptability of young olive trees by changes on redox status and ionome

Different SA concentrations (10, 100 and 1000 μM) were applied in young olive trees (Olea europaea L.) subjected to drought and rewatering. Plants treated with 10 μM exhibited a close behavior to SA-starved plants. Although both 100 and 1000 μM improved the balance between ROS production and scavenging, 100 μM was more efficient. During drought, 100 μM improved ROS detoxification and scavenging by the maintenance or overaccumulation of soluble proteins. During recovery, soluble proteins return to well-watered values and increased the investment in non-enzymatic antioxidants. 100 μM was also the most effective in plant ionome regulation, improving macro and micronutrients uptake, namely P, Fe, Mn and Zn, and changing mineral allocation patterns. Therefore, 100 μM also countered the drought-induced decline in total plant biomass accumulation. The application of suitable SA concentrations is an efficient tool to improve cellular homeostasis and growth of plants subjected to recurrent drought episodes.