KpCHX Gene From Kosteletzkya Pentacarpos Confers Salt Tolerance In Arabidopsis Thaliana

Salinity stress is also considered as a hyperionic stress. The major effect of salinity stress is the accumulation of Na~+ and Cl- ions in plant tissues which is exposed to saline soil. A large number of absorption in both Na~+ and Cl- lead to severe ion imbalance. High Na~+ concentration inhibits uptake of K~+ ions which is an essential element for growth and development, and low K~+ concentration results to lower productivity even lead to death.Kosteletzkya pentacarpos is a dicotyledonous halophyte plants, they can tolerate salt environment up to 420 mM NaCl, and produce viable seeds. Kosteletzkya pentacarpos salt tolerance relies on controlled uptake and compartmentalization of Na~+, K~+ and Cl-and the synthesis of compatible organic solutes.Kosteletzkya pentacarposKpCHX gene, a member of CHX family(cation/ H+ exchanger family),was proved to up-regulated in roots under salt stress. Therefore, wepropose a hypothesis that KpCHX maybe participate in the salt tolerance of K. pentacarpos.In addition, it share a high identity with AtCHX17 which is involved in K~+ acquisition and homeostasis, we predicted that KpCHX have a function in K~+ homeostasis.To investigate the roles of the KpCHX genes in K~+ transport and salt tolerance, six overexpression vector 2×35S–KpCHX–Nos was constructed and transformed into Arabidopsis thaliana ecotype Columbia(WT) using floral dipping. PCR analysis indicated the KpCHX gene was integrated into the genome of Arabidopsis, and western blot analysis demonstrated the KpCHX protein was expressed in C45 transgenic Arabidopsis. Salt stress treatment was performed and the root length, leaf numbers,fresh weight,dry weight, MDA content, proline contentwere measured between WT and C45 transgenic Arabidopsis. The results showed that theC45 transgenic Arabidopsis had a higher salt tolerance than WT. Subsequently, K~+ deficient treatment was performed and the result suggested that C45 transgenic Arabidopsis growing vigorous while WT getting shrivel under K~+ deficient condition. In summary, the results indicated the KpCHX overexpression can enhance plant tolerance during salt stress and improve plant growth under K~+ deficient condition.