Research
Salt (NaCl) affects more than 20 % of the world's irrigated land and causes huge economic losses by limiting agricultural production due to increased salinization. Soil salinization is a significant global problem that affects plant development through ion toxicity and nutrient imbalance. In plants, salt stress triggers two sequential responses. First, there is a rapid osmotic shock that reduces relative water content, leaf water potential, stomatal conductance, and turgor potential. After this first phase, a phase of ion homeostasis is induced, triggering salt toxicity and accelerating senescence of mature leaves.
The facultative halophyte Chenopodium quinoa, for example, is naturally protected from damage caused by salt stress: the salt-tolerant plant deposits salt absorbed from the soil into small bladders on the leaf surface. (Photo: Turcios)
Salt stress is induced by high concentrations of sodium (Na+) and chloride (Cl-) in the soil. Excess Na+ and Cl- ions compete with other nutrient elements and can lead to reduced nutrient uptake and translocation, and thus to imbalances in nutrient status. However, Na+ is not essential for plants. Potassium (K+) in particular is susceptible to this competition because of its similar chemical properties to Na+, for example, in ionic radius and hydration energy. K+ is an essential plant nutrient and is required for enzyme activity, energy transfer, protein synthesis, osmoregulation, stomatal movement, phloem transport, anion-cation balance, and stress resistance. K+ is particularly important as an inorganic osmotic element in plant cells, and therefore adequate K+ supply is critical for the regulation of turgor-controlled processes such as stomatal movement and cell elongation.
The interaction between Na+ and K+ can have negative effects on K+ uptake, which is regulated by passive and active transport systems. K+ is transported from roots to shoots by transpiration-driven water flux in the xylem, which is impaired during salt stress. Disruption of K+ homeostasis occurs, which is crucial for salt stress tolerance. For optimal plant growth, Na+ uptake must be reduced and K+ uptake increased, as a higher K+/Na+ ratio favors salt stress tolerance in plants.
The goal of this project is to gain insight into the importance of K+ in mitigating salt stress and to investigate the response of plants to salinity using different K+ supplies.
