Proteins and DNA related to salt tolerance in plants

1. A method of increasing the salt tolerance of a plant in need thereof, comprising increasing the expression of a polynucleotide encoding a polypeptide that is at least 95% identical to the amino acid sequence of SEQ ID NO: 2, wherein said polypeptide has Na + /H + antiporter activity, in said plant as compared to the expression of said polynucleotide in the wild-type of said plant, and wherein said increasing the expression is by either increasing the copy number of said polynucleotide as compared to the wild-type plant or by replacing the native promoter of said polynucleotide with a stronger promoter.

2. The method of claim 1 , wherein said polynucleotide comprises the sequence of SEQ ID NO: 1.

3. The method of claim 1 , wherein said polynucleotide encodes the polypeptide of SEQ ID NO: 2.

4. The method of claim 1 , wherein said plant is Arabidopsis thaliana.

5. The method of claim 1 , wherein said plant is selected from the group consisting of wheat, corn, peanut cotton, oat, and soybean plant.

6. The method of claim 1 , wherein said increasing the expression comprises increasing the copy number of said polynucleotide as compared to the wild-type plant.

7. The method of claim 1 , wherein said increasing the expression comprises replacing the native promoter of said polynucleotide with a stronger promoter.

8. The method of claim 1 , wherein said plant is a monocotyledonous plant.

9. The method of claim 1 , wherein said plant is a dicotyledonous plant.

10. The method of claim 1 , wherein said increasing the expression is in a plant organ.

11. The method of claim 10 , wherein said plant organ is selected from the group consisting of leaves, stems, and roots.

12. The method of claim 1 , wherein said increasing the expression is in the whole plant.

13. The method of claim 1 , wherein said increasing the expression is in the seeds of said plant.