Overexpression of a Plasma Membrane Bound Na + /H + Antiporter-Like Protein ( SbNHXLP ) Confers Salt Tolerance and Improves Fruit Yield in Tomato by Maintaining Ion Homeostasis

A Na /H antiporter-like protein (NHXLP) was isolated from L. ( ) and validated by overexpressing in tomato for salt tolerance. Homozygous T transgenic lines when evaluated for salt tolerance, accumulated low Na and displayed enhanced salt tolerance compared to wild-type plants (WT). This is consistent with the amiloride binding assay of the protein. Transgenics exhibited higher accumulation of proline, K , Ca , improved cambial conductivity, higher PSII, and antioxidative enzyme activities than WT. Fluorescence imaging results revealed lower Na and higher Ca levels in transgenic roots. Co-immunoprecipitation experiments demonstrate that NHXLP interacts with a cation proton antiporter protein2 ( CHX2). qRT-PCR results showed upregulation of and upon treatment with 200 mM NaCl and 100 mM potassium nitrate. is known to be involved in K acquisition, and the interaction between these two proteins might help to accumulate more K ions, and thus maintain ion homeostasis. These results strongly suggest that plasma membrane bound NHXLP involves in Na exclusion, maintains ion homeostasis in transgenics in comparison with WT and alleviates NaCl stress.