The wheat NHX antiporter gene TaNHX2 confers salt tolerance in transgenic alfalfa by increasing the retention capacity of intracellular potassium
- 798 Downloads
Previous studies have shown that TaNHX2 transgenic alfalfa (Medicago sativa L.) accumulated more K+ and less Na+ in leaves than did the wild-type plants. To investigate whether the increased K+ accumulation in transgenic plants is attributed to TaNHX2 gene expression and whether the compartmentalization of Na+ into vacuoles or the intracellular compartmentalization of potassium is the critical mechanism for TaNHX2-dependent salt tolerance in transgenic alfalfa, aerated hydroponic culture was performed under three different stress conditions: control condition (0.1 mM Na+ and 6 mM K+ inside culture solution), K+-sufficient salt stress (100 mM NaCl and 6 mM K+) and K+-insufficient salt stress (100 mM NaCl and 0.1 mM K+). The transgenic alfalfa plants had lower K+ efflux through specific K+ channels and higher K+ absorption through high-affinity K+ transporters than did the wild-type plants. Therefore, the transgenic plants had greater K+ contents and [K+]/[Na+] ratios in leaf tissue and cell sap. The intracellular compartmentalization of potassium is critical for TaNHX2-induced salt tolerance in transgenic alfalfa.
KeywordsNHX protein Na+/H+ antiporter Potassium Transgenic alfalfa Salt tolerance
This work was supported by the Natural Science Foundation of Hebei Province, China (Grant No. C2013301033) and National Major Project for Transgenic Crops of Chinese Agriculture Ministry (Grant No. 2014ZX0800402B).
- Bassil E, Ohto M, Esumi T, Tajima H, Zhu Z, Cagnac O, Belmonte M, Peleg Z, Yamaguchi T, Blumwald E (2011a) The Arabidopsis intracellular Na+/H+ antiporters NHX5 and NHX6 are endosome associated and necessary for plant growth and development. Plant Cell 23:224–239PubMedCentralPubMedCrossRefGoogle Scholar
- Bassil E, Tajima H, Liang YC, Ohto M, Ushijima K, Nakano R, Esumi T, Coku A, Belmonte M, Blumwald E (2011b) The Arabidopsis Na+/H+ antiporters NHX1 and NHX2 control vacuolar pH and K+ homeostasis to regulate growth, flower development, and reproduction. Plant Cell 23:3482–3497PubMedCentralPubMedCrossRefGoogle Scholar
- Chen GP, Wang HZ, Shi NG, Chen SY (2006) Na+/H+ antiporter and its relationship with plant salt tolerance. China Biotechnol 26(5):101–106Google Scholar
- Sun J, Zhang X, Deng SR, Zhang CL, Wang MJ, Ding MQ, Zhao R, Shen X, Zhou XY, Lu CF, Chen SL (2012) Extracellular ATP signaling is mediated by H2O2 and cytosolic Ca2+ in the salt response of Populus euphratica cells. PLoS ONE 7:e53136. doi: 10.1371/journal.pone.0053136 PubMedCentralPubMedCrossRefGoogle Scholar