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- Title
The AtNHX1 exchanger mediates potassium compartmentation in vacuoles of transgenic tomato.
- Authors
Leidi, Eduardo O.; Barragán, Verónica; Rubio, Lourdes; El-Hamdaoui, Abdelaziz; Ruiz, M. Teresa; Cubero, Beatriz; Fernández, José A.; Bressan, Ray A.; Hasegawa, Paul M.; Quintero, Francisco J.; Pardo, José M.
- Abstract
NHX-type antiporters in the tonoplast have been reported to increase the salt tolerance of various plants species, and are thought to mediate the compartmentation of Na+ in vacuoles. However, all isoforms characterized so far catalyze both Na+/H+ and K+/H+ exchange. Here, we show that AtNHX1 has a critical involvement in the subcellular partitioning of K+, which in turn affects plant K+ nutrition and Na+ tolerance. Transgenic tomato plants overexpressing AtNHX1 had larger K+ vacuolar pools in all growth conditions tested, but no consistent enhancement of Na+ accumulation was observed under salt stress. Plants overexpressing AtNHX1 have a greater capacity to retain intracellular K+ and to withstand salt-shock. Under K+-limiting conditions, greater K+ compartmentation in the vacuole occurred at the expense of the cytosolic K+ pool, which was lower in transgenic plants. This caused the early activation of the high-affinity K+ uptake system, enhanced K+ uptake by roots, and increased the K+ content in plant tissues and the xylem sap of transformed plants. Our results strongly suggest that NHX proteins are likely candidates for the H+-linked K+ transport that is thought to facilitate active K+ uptake at the tonoplast, and the partitioning of K+ between vacuole and cytosol.
- Subjects
PLANT vacuoles; TONOPLASTS; PLANT genetic engineering; POTASSIUM; PLANT cells &; tissues
- Publication
Plant Journal, 2010, Vol 61, Issue 3, p495
- ISSN
0960-7412
- Publication type
Article
- DOI
10.1111/j.1365-313X.2009.04073.x