The AtNHX1 exchanger mediates potassium compartmentation in vacuoles of transgenic tomato.
Plant J
; 61(3): 495-506, 2010 Feb 01.
Article
em En
| MEDLINE
| ID: mdl-19912566
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.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Potássio
/
Vacúolos
/
Arabidopsis
/
Trocadores de Sódio-Hidrogênio
/
Solanum lycopersicum
/
Proteínas de Transporte de Cátions
/
Proteínas de Arabidopsis
Idioma:
En
Revista:
Plant J
Assunto da revista:
BIOLOGIA MOLECULAR
/
BOTANICA
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Espanha