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Functional characterization of a wheat NHX antiporter gene TaNHX2 that encodes a K(+)/H(+) exchanger.

ABSTRACT: The subcellular localization of a wheat NHX antiporter, TaNHX2, was studied in Arabidopsis protoplasts, and its function was evaluated using Saccharomyces cerevisiae as a heterologous expression system. Fluorescence patterns of TaNHX2-GFP fusion protein in Arabidopsis cells indicated that TaNHX2 localized at endomembranes. TaNHX2 has significant sequence homology to NHX sodium exchangers from Arabidopsis, is abundant in roots and leaves and is induced by salt or dehydration treatments. Western blot analysis showed that TaNHX2 could be expressed in transgenic yeast cells. Expressed TaNHX2 protein suppressed the salt sensitivity of a yeast mutant strain by increasing its K(+) content when exposed to salt stress. TaNHX2 also increased the tolerance of the strain to potassium stress. However, the expression of TaNHX2 did not affect the sodium concentration in transgenic cells. Western blot analysis for tonoplast proteins indicated that the TaNHX2 protein localized at the tonoplast of transgenic yeast cells. The tonoplast vesicles from transgenic yeast cells displayed enhanced K(+)/H(+) exchange activity but very little Na(+/)H(+) exchange compared with controls transformed with the empty vector; Na(+)/H(+) exchange was not detected with concentrations of less than 37.5 mM Na(+) in the reaction medium. Our data suggest that TaNHX2 is a endomembrane-bound protein and may primarily function as a K(+)/H(+) antiporter, which is involved in cellular pH regulation and potassium nutrition under normal conditions. Under saline conditions, the protein mediates resistance to salt stress through the intracellular compartmentalization of potassium to regulate cellular pH and K(+) homeostasis.

SUBMITTER: Xu Y

PROVIDER: S-EPMC3815223 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Functional characterization of a wheat NHX antiporter gene TaNHX2 that encodes a K(+)/H(+) exchanger.

Xu Yuanyuan Y Zhou Yang Y Hong Sha S Xia Zhihui Z Cui Dangqun D Guo Jianchun J Xu Haixia H Jiang Xingyu X

PloS one 20131101 11

The subcellular localization of a wheat NHX antiporter, TaNHX2, was studied in Arabidopsis protoplasts, and its function was evaluated using Saccharomyces cerevisiae as a heterologous expression system. Fluorescence patterns of TaNHX2-GFP fusion protein in Arabidopsis cells indicated that TaNHX2 localized at endomembranes. TaNHX2 has significant sequence homology to NHX sodium exchangers from Arabidopsis, is abundant in roots and leaves and is induced by salt or dehydration treatments. Western b ...[more]

PMID: 24223765

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Project description:Soil salinization, which is the accumulation of salt in soil, can have a negative impact on crop growth and development by creating an osmotic stress that can reduce water uptake and cause ion toxicity. The NHX gene family plays an important role in plant response to salt stress by encoding for Na+/H+ antiporters that help regulate the transport of sodium ions across cellular membranes. In this study, we identified 26 NHX genes in three cultivars of Cucurbita L., including 9 Cucurbita moschata NHXs (CmoNHX1-CmoNHX9), 9 Cucurbita maxima NHXs (CmaNHX1-CmaNHX9) and 8 Cucurbita pepo NHXs (CpNHX1-CpNHX8). The evolutionary tree splits the 21 NHX genes into three subfamilies: the endosome (Endo) subfamily, the plasma membrane (PM) subfamily, and the vacuole (Vac) subfamily. All the NHX genes were irregularly distributed throughout the 21 chromosomes. 26 NHXs were examined for conserved motifs and intron-exon organization. These findings suggested that the genes in the same subfamily may have similar functions while genes in other subfamilies may have functional diversity. The circular phylogenetic tree and collinearity analysis of multi-species revealed that Cucurbita L. had a substantially greater homology relationship than Populus trichocarpa and Arabidopsis thaliana in terms of NHX gene homology. We initially examined the cis-acting elements of the 26 NHXs in order to investigate how they responded to salt stress. We discovered that the CmoNHX1, CmaNHX1, CpNHX1, CmoNHX5, CmaNHX5, and CpNHX5 all had numerous ABRE and G-box cis-acting elements that were important to salt stress. Previous transcriptome data showed that in the mesophyll and veins of leaves, many CmoNHXs and CmaNHXs, such as CmoNHX1, responded significantly to salt stress. In addition, we heterologously expressed in A. thaliana plants in order to further confirm the response of CmoNHX1 to salt stress. The findings demonstrated that during salt stress, A. thaliana that had CmoNHX1 heterologously expression was found to have decreased salt tolerance. This study offers important details that will aid in further elucidating the molecular mechanism of NHX under salt stress.

Dataset Information

Functional characterization of a wheat NHX antiporter gene TaNHX2 that encodes a K(+)/H(+) exchanger.

Publications

Functional characterization of a wheat NHX antiporter gene TaNHX2 that encodes a K(+)/H(+) exchanger.

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