Isolation of OSCAs in wheat and over-expression of TaOSCA14D increased salt stress tolerance

Salt stress is a major environmental factor that limits plant growth and productivity. In the early stage of salt stress, the intracellular Ca²⁺ concentration elevates, thereby triggering osmotic stress tolerance signaling pathway. OSCAs encode hyperosmotic gated calcium channels and function as osmotic sensors in Arabidopsis. But the functions of OSCAs in wheat responding to salt stress have not been elucidated. In this study, we identified 42 TaOSCAs and examined their expression pattern in 12 tissues and under salt stress. Further, the salt inducible TaOSCA14D was selected for functional study in response to salt stress. TaOSCA14D was induced by NaCl, PEG, exogenous ABA treatment. Over-expression of TaOSCA14D in Arabidopsis and wheat increased salt stress tolerance. Salt stress related marker genes SnRK2s, ABFs, RD29B were higher expressed in TaOSCA14D transgenic plants than in the wild type under NaCl treatment. Furthermore, the soluble sugar and proline content were higher in transgenic plants than in wild-type ones. Over-expression of TaOSCA14D promoted flowering, decreased spike length and the grain number of per spike. All these results shed some light on the function of OSCAs in tolerance to salt stress and its roles in agronomic trait in wheat.