Salinity inhibits the induction of physiological responses to iron and potassium deficiency in two phylogenetically related species: Arabidopsis thaliana (glycophyte) and Cakile maritima (halophyte)

Potassium (K+) and iron (Fe) deficiency impeded plant growth and development. Because of the increase in soil salinization, plant challenged with nutrient availability were arisen. Thus, understanding the effect of salinity on the mechanisms involved in macro and microelement uptake is crucial. Two kinds of experiments were used to study the interactive effect of salinity with K+ or Fe deficiency. In the first one, Cakile maritima was subjected to the treatments for a longer period while in the second one, C. maritima and Arabidopsis thaliana were subjected to similar treatments but for a shorter period. Long-term responses to salinity and their interaction with K+ or Fe deficiency reduced shoot and root growth, chlorophyll content, generated an imbalance in nutrient status. Both deficiencies increased root ethylene production. A stimulation of root ferric chelate reductase (FCR) activity was only recorded in Fe deficient plants. Salinity increased Na+ concentration notably in shoots, disturbed plant nutrient homeostasis, inhibited root hair proliferation and abolished the induction of FCR activity and ethylene synthesis either by K+ or Fe shortage. Similar results were obtained in C. maritima and A. thaliana once treatments were imposed during a shorter period with the halophyte being more tolerant. In A. thaliana, the mechanisms involved in K+ and Fe uptake were inhibited by high salinity. Salinity inhibited the induction of several physiological and biochemical responses either by K+ or Fe deficiency by abolishing the main mechanisms involved in the uptake of both elements.