Characterization of a root aninon channel that plays a pivotal role in plant chloride nutrition

1. Background and Objectives: Although classified as a micronutrient, plants accumulate chloride (Cl-) to levels that are typical of the content of a macronutrient. This enables plants to improve cell osmoregulation, water relations and growth under optimal growing conditions (Franco-Navarro et al., 2016). Under salt stress conditions Cl- impairs nitrate (NO3-) nutrition due, apparently, to competition for membrane transport mechanisms. Chloride loading into root xylem vessels is a key mechanism regulating shoot Cl- accumulation (Brumós et al., 2010). To maintain an appropriate balance between both anions, xylem loading of NO3- and Cl- has to be tightly regulated. Given the thermodynamics of anion transport, release of Cl- and NO3- into the root xylem is highly likely to be electrochemically passive and, therefore, facilitated by plasma membrane anion channels that are not yet identified. The NO3- and Cl- conductance of xylem parenchyma cells registered by early patch clamp studies are reminiscent to electrical characteristics of the recently identified anion channels from the slow-type (SLAC/SLAH) family, consisting of five members in Arabidopsis thaliana. To determine the involvement of the slow-type channels in plant Cl- homeostasis, a member of the gene family predominantly expressed in the root has been functionally characterized 2. Material and Methods: Tissue and cell-specific expression pattern of the gene was determined in different transgenic lines of Arabidopsis thaliana Col-0 expressing the chimeric GUS::GFP marker gene under the control of the native gene promoter. Gene expression in response to different abiotic stress and nutritional treatments was quantified by Quantitative Real Time-PCR (qPCR). Homozygous knock-out mutant plants were phenotyped according to plant growth, shoot Cl- content and xylem sap Cl- concentration. Electrophysiological activity of the gene product was characterized through functional expression of the gene in Xenopus laevis oocytes and Double-Electrode Voltage-Clamp (DEVC) measurements. 3. Results: The following results regarding the functional characterization of a gene encoding a slow-type root anion channel will be presented: cell-type expression, gene regulation, knockout mutant phenotypes, as well as electrophysiological and regulatory mechanisms involved in protein activity regulation. 4. Conclusions: A novel anion channel with a pivotal role in Cl- homeostasis in higher plants has been characterized.

Bibliographic Details

Main Authors:	Cubero Font, Paloma, Espartero, Joaquín, Maierhofer, Tobias, Rosales Villegas, Miguel Á., Hedrich, Rainer, Díaz-Rueda, P., Geiger, Dietmar, Colmenero Flores, José M.
Other Authors:	Ministerio de Economía y Competitividad (España)
Format:	comunicación de congreso biblioteca
Published:	Sociedad Española de Fisiología Vegetal 2016-09-25
Online Access:	http://hdl.handle.net/10261/158815 http://dx.doi.org/10.13039/501100003329
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