Article

Molecular characterization of a novel Na+/H+ antiporter cDNA from Eucalyptus globulus

Fundación Ciencia & Vida, Zañartu 1482, Ñuñoa, Santiago, Chile.
Biochemical and Biophysical Research Communications (Impact Factor: 2.3). 12/2012; 430(2). DOI: 10.1016/j.bbrc.2012.11.118
Source: PubMed

ABSTRACT

Environmental stress factors such as salt, drought and heat are known to affect plant productivity. However, high salinity is spreading throughout the world, currently affecting more than 45 million hectares. One of the mechanisms that allow plants to withstand salt stress consists on vacuolar sequestration of Na(+), through a Na+/H+ antiporter. We isolated a new vacuolar Na(+)/H(+) antiporter from Eucalyptus globulus from a cDNA library. The cDNA had a 1,626 bp open reading frame encoding a predicted protein of 542 amino acids with a deduced molecular weight of 59.1 KDa. Phylogenetic and bioinformatic analyses indicated that EgNHX1 localized in the vacuole. To assess its role in Na(+) exchange, we performed complementation studies using the Na(+) sensitive yeast mutant strain Δnhx1. The results showed that EgNHX1 partially restored the salt sensitive phenotype of the yeast Δnhx1 strain. However, its overexpression in transgenic Arabidopsis confers tolerance in the presence of increasing NaCl concentrations while the wild type plants exhibited growth retardation. Expression profiles of Eucalyptus seedlings subjected to salt, drought, heat and ABA treatment were established. The results revealed that Egnhx1 was induced significantly only by drought. Together, these results suggest that the product of Egnhx1 from Eucalyptus globulus is a functional vacuolar Na(+)/H(+) antiporter.

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    • "To date, a number of vacuolar Na+/H+ antiporter genes have been isolated and characterized from different plant species. Many studies have been reported to improve salt stress resistance of plants by over-expression of vacuolar Na+/H+ antiporter genes such as AtNHX1, GhNHX1, OsNHX1, and EgNHX1 etc [3], [4], [6], [7]. All these results suggest that vacuolar Na+/H+ antiporter genes play significant roles in salt tolerance. "
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