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High Ca2+ reverts the repression of high-affinity K+ uptake produced by Na+ in Solanum lycopersycum L. (var. microtom) plants created by Hayet Bacha, Reyes Ródenas, Elvira López-Gómez, Manuel Francisco García-Legaz, Manuel Nieves-Cordones, Rosa M. Rivero, Vicente Martínez, M. Ángeles Botella and Francisco Rubio

By: Contributor(s): Material type: TextTextSeries: Journal of plant physiology ; Volume 180Amsterdam: Elsevier GmbH, 2015Content type:
  • text
Media type:
  • unmediated
Carrier type:
  • volume
ISSN:
  • 0176-1617
Subject(s): LOC classification:
  • QK711.2 JOU
Online resources: Abstract: Potassium (K+) is an essential nutrient for plants which is acquired by plant roots through the operation of specific transport systems. Abiotic stress conditions such as salinity impair K+ nutrition because, in addition to other effects, high salt concentrations in the solution bathing the roots inhibit K+ uptake systems. This detrimental effect of salinity is exacerbated when external K+ is very low and the only system capable of mediating K+ uptake is one with high-affinity for K+, as that mediated by transporters of the HAK5 type. Increasing external Ca2+ has been shown to improve K+ nutrition under salinity and, although the specific mechanisms for this beneficial effect are largely unknown, they are beginning to be understood. The genes encoding the HAK5 transporters are induced by K+ starvation and repressed by long-term exposure to high Na+. This occurs in parallel with the hyperpolarization and depolarization of root cell membrane potential. In the present study it is shown in tomato plants that the presence of high Ca2+ during the K+ starvation period that leads to LeHAK5 induction, counteracts the repression exerted by high Na+. High Ca2+ reduces the Na+-induced plasma membrane depolarization of root cells, resorting one of the putative first steps in the low-K+ signal cascade. This allows proper LeHAK5 expression and functional high-affinity K+ uptake at the roots. Thus, the maintenance of HAK5-mediated K+ nutrition under salinity by high Ca2+ can be regarded as a specific beneficial effect of Ca2+ contributing to salt tolerance in plants.
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Item type Current library Call number Vol info Status Notes Date due Barcode
Journal Article Journal Article Main Library - Special Collections QK711.2 JOU (Browse shelf(Opens below)) Vol. 180 (pages72-79) Not for loan For in house use only

Potassium (K+) is an essential nutrient for plants which is acquired by plant roots through the operation of specific transport systems. Abiotic stress conditions such as salinity impair K+ nutrition because, in addition to other effects, high salt concentrations in the solution bathing the roots inhibit K+ uptake systems. This detrimental effect of salinity is exacerbated when external K+ is very low and the only system capable of mediating K+ uptake is one with high-affinity for K+, as that mediated by transporters of the HAK5 type. Increasing external Ca2+ has been shown to improve K+ nutrition under salinity and, although the specific mechanisms for this beneficial effect are largely unknown, they are beginning to be understood. The genes encoding the HAK5 transporters are induced by K+ starvation and repressed by long-term exposure to high Na+. This occurs in parallel with the hyperpolarization and depolarization of root cell membrane potential. In the present study it is shown in tomato plants that the presence of high Ca2+ during the K+ starvation period that leads to LeHAK5 induction, counteracts the repression exerted by high Na+. High Ca2+ reduces the Na+-induced plasma membrane depolarization of root cells, resorting one of the putative first steps in the low-K+ signal cascade. This allows proper LeHAK5 expression and functional high-affinity K+ uptake at the roots. Thus, the maintenance of HAK5-mediated K+ nutrition under salinity by high Ca2+ can be regarded as a specific beneficial effect of Ca2+ contributing to salt tolerance in plants.

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