Molecular cloning and the expression of the Na+/H+antiporter in the monocot halophyte Leptochloa fusca (L.) Kunth

• We cloned a vacuolar Na+/H+ antiporter cDNA (Lf NHX1) from Leptochloa fusca L. by cDNA and RACE methods using degenerate primers.
• Lf NHX sequence contains 2,452 nucleotides and an open-reading frame of 1,620 nucleotides.
• The effects of NaCl stress were surveyed on Na+/H+ antiporter at early times of NaCl treatment through the Real time PCR.
• Ion content of treated and controls were surveyed.
• Treated plants accumulated more Na + ? in roots and kept a relative high Na + ?/K?+ ratio in comparison with control

The plant vacuolar Na+/H+ antiporter plays an important role in salt tolerance. A vacuolar Na+/H+ cDNA (LfNHX1) gene was cloned from Leptochloa fusca(L.) Kunth, a halophyte forage grass, by cDNA and RACE methods using degenerate primers. The results show that the LfNHX sequence contains 2452 nucleotides and an open-reading frame of1620 nucleotides that encode a protein of 540 amino acids with a deduced molecular mass of 59.8 kDa. The deduced amino acid contains the consensus amiloride-binding domain. The effects of NaCl stress on the Na+/ H+ gene expression were analysed using Real Time PCR. The analysis showed that the expression level of LfNHX1 increases in response to different levels of NaCl, indicating that V-Na+/H+ plays an important role in salt tolerance in this plant.