The K+/H+ antiporter AhNHX1 improved tobacco tolerance to NaCl stress by enhancing K+ retention
High salinity is the one of important factors limiting plant growth and crop production. Many NHX-type antiporters have been reported to catalyze K+/H+ exchange to mediate salt stress. This study shows that an NHX gene from Arachis hypogaea L. has an important role in K+ uptake and transport, which affects K+ accumulation and plant salt tolerance. When overexpressing AhNHX1, the growth of tobacco seedlings is improved with longer roots and a higher fresh weight than the wild type (WT) under NaCl treatment. Meanwhile, when exposed to NaCl stress, the transgenic seedlings had higher K+/H+ antiporter activity and their roots got more K+ uptake. NaCl stress could induce higher K+ accumulation in the roots, stems, and leaves of transgenic tobacco seedlings but not Na+ accumulation, thus, leading to a higher K+/Na+ ratio in the transgenic seedlings. Additionally, the AKT1, HAK1, SKOR, and KEA genes, which are involved in K+ uptake or transport, were induced by NaCl stress and kept higher expression levels in transgenic seedlings than in WT seedlings. The H+-ATPase and H+-PPase activities were also higher in transgenic seedlings than in the WT seedlings under NaCl stress. Simultaneously, overexpression of AhNHX1 increased the relative distribution of K+ in the aerial parts of the seedlings under NaCl stress. These results showed that AhNHX1 catalyzed the K+/H+ antiporter and enhanced tobacco tolerance to salt stress by increasing K+ uptake and transport.
KeywordsArachis hypogaea L. K+/H+ Antiporter K+ transport K+ uptake Salt stress
Unable to display preview. Download preview PDF.
- Bassil E, Tajima H, Liang Y, Ohto M, Ushijima K, Nakano R, Esumi T, Coku A, Belmonte M, Blumwald E (2011) The Arabidopsis Na+/H+ antiporters NHX1 and NHX2 control vacuolar pH and K+ homeostasis to regulate growth, flower development, and reproduction. Plant Cell 23:3482–3497CrossRefPubMedPubMedCentralGoogle Scholar
- Drechsler N, Zheng Y, Bohner A, Nobmann B, von Wiren N, Kunze R, Rausch C (2015) Nitrate-dependent control of shoot K homeostasis by the nitrate transporter1/peptide transporter family member NPF7.3/NRT1.5 and the stelar K+ outward rectifier SKOR in Arabidopsis. Plant Physiol 169:2832–2847PubMedPubMedCentralGoogle Scholar
- Rodríguez-Rosales MP, Jiang X, Galvez FJ, Aranda MN, Cubero B, Sauib M, Zorb C, Rengel Z, Schuber S (2005) The expression of the endogenous vacuolar Na+/H+ antiporters in roots and shoots correlates positively with the salt resistance of wheat (Triticum aestivum L.). Plant Sci 169:959–965CrossRefGoogle Scholar
- Yin X, Liang X, Zhang R, Yu L, Xu G, Zhou Q, Zhan X (2015) Impact of phenanthrene exposure on activities of nitrate reductase, phosphoenolpyruvate carboxylase, vacuolar H+-pyrophosphatase and plasma membrane H+-ATPase in roots of soybean, wheat and carrot. Environ Exp Bot 113:59–66CrossRefGoogle Scholar