Complementation with TaNCL2-A reinstates growth and abiotic stress response in atncl mutant of Arabidopsis

Abstract

The sodium/calcium exchanger-like (NCL) transporters are members of Ca^2 +/Cation antiporters (CaCAs) family, localized at the tonoplast, and primarily involved in Ca²⁺ homeostasis and stress response. They transport Ca²⁺ to the cytosol and sequester cytosolic Na⁺ into the vacuole. Therefore, the atncl mutant of Arabidopsis thaliana is prone to salinity stress. The functional complementation of TaNCL2-A of Triticum aestivum improved abiotic stress response and various morpho-physio-biochemical parameters in atncl mutant. The TaNCL2-A complementation increased the seed germination rate and root length of atncl mutant during salinity and drought stress conditions. The exogenous Ca²⁺ application further improved the stress tolerance in the complemented lines. The results suggested that the modulation of cytosolic Ca²⁺ by TaNCL2-A expression and/or exogenous Ca²⁺ application could reinstate growth and abiotic stress response in atncl mutant. TaNCL2-A also reduced the impact of ABA on seed germination. In addition, exogenous IAA induced lateral roots formation in all the lines. Biochemical and physiological analyses revealed increased proline, chlorophylls, carotenoids and relative water content (RWC), and reduced malondialdehyde (MDA), H₂O₂ and relative electrical conductivity (REC) in TaNCL2-A complemented lines. The results highlighted the function of TaNCL2-A gene in stress response, and its potential application in crop improvement strategies in future studies.