Molecular and functional comparisons of the vacuolar Na+/H+ exchangers originated from glycophytic and halophytic species
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A novel vacuolar Na+/H+ exchanger, CgNHX1, was cloned from a halophytic species Chenopodium glaucum by using reverse transcriptase-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) technique. Sequence alignment and phylogenetic analysis of 22 NHX genes from GenBank as well as the new CgNHX1 gene indicate that NHX genes shared a great degree of similarity, regardless of their glycophytic or halophytic origin. Expression of the CgNHX1 gene was induced by NaCl and peaked at 400 mmol/L NaCl. Overexpression of NHX1 genes in rice enhanced their tolerance to salt stress. However, there is no significant difference in salt tolerance among the transgenic rice plants overexpressing the NHX1 genes from either glycophytic or halophytic species. The Na+ content of both the wild type (WT) and transgenic plants increased when exposed to 50 and 100 mmol/L NaCl, and the Na+ concentration in transgenic plants was marginally higher than that of WT. Our data demonstrate that the overexpression of the NHX1 gene from either glycophytic or halophytic species resulted in the enhanced tolerance to salt stress at a similar level, suggesting that NHX gene per se might not be the reason accounting for the difference in salt tolerance between glycophytes and halophytes.
Key wordsNHX gene Rice transformation Salt stress Tolerance
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- Apse, M.P., Sottosanto, J.B., Blumwald, E., 2003. Vacuolar cation/H+ exchange, ion homeostasis, and leaf development are altered in a T-DNA insertional mutant of AtNHX1, the Arabidopsis vacuolar Na+/H+ antiporter. Plant J., 36(2):229–239. [doi:10.1046/j.1365-313X.2003.01871.x]PubMedCrossRefGoogle Scholar
- Brini, F., Hanin, M., Mezghani, I., Berkowitz, G.A., Masmoudi, K., 2007. Overexpression of wheat Na+/H+ antiporter TNHX1 and H+-pyrophosphatase TVP1 improve salt-and drought-stress tolerance in Arabidopsis thaliana plants. J. Exp. Bot., 58(2):301–308. [doi:10.1093/jxb/erl251]PubMedCrossRefGoogle Scholar
- Hofmann, K.S.W., 1993. TM base—A database of membrane spanning proteins segments. Biol. Chem. Hoppe-Seyler, 347:166–172.Google Scholar
- Jones, R.G.W., 1981. Salt Tolerance. In: Johnson, C.B. (Ed.), Physiological Processes. Limiting Plant Productivity. Butterworths, Iondon, p.271–292.Google Scholar
- Li, J.Y., Zhang, F.C., Ma, J., Cai, L., Bao, Y.G., Wang, B., 2003. Using RT-PCR to amplify the NHX gene fragment in Atriplex dimorphostegia. Plant Physiol. Commun., 6(6):585–588 (in Chinese).Google Scholar
- Xiong, L.M., Zhu, J.K., 2002. Salt Tolerance. In: Somerville, C.R., Meyerowitz, E.M. (Eds.), The Arabidopsis Book. American Society of Plant Biologists, Rockville, MD, p.1–22. [doi:10.1199/tab.0048]Google Scholar