Expression of the Vacuolar Na+/H+ Antiporter Gene (NHX1) in Three Plantago Species Differing in Salt Tolerance

Abstract

[EN] We have isolated full-length cDNA clones of the NHX1 gene – encoding the vacuolar Na+ /H+ antiporter – from three Plantago species (P. crassifolia, P. coronopus and P. major) differing in salt tolerance. A phylogenetic tree of their deduced protein sequences and those of NHX1 antiporters previously isolated from other species suggested the presence of some structural features characteristic of the proteins of salt tolerant taxa. The expression patterns of the NHX1 genes in the presence of salt correlated with the relative degree of salt tolerance of the three species: no induction was detected in the least tolerant P. major – and in the glycophyte A. thaliana – and the highest and quickest induction was observed in the most tolerant P. crassifolia. These data support the hypothesis that the NHX1 antiporters play a functional role in the mechanisms of salt tolerance in plants.