Cloning and expression of the AtGRP9 gene related to salt stress tolerance in Arabidopsis thaliana.

The fission yeast Schizosaccharomyces pombe is a single cell eukaryotic organism. Taking advantage of the genetic simplicity of S.pombe and of the functional conservation of some salt tolerance-related proteins, this organism was used as a simple system to identify Arabidopsis thaliana salt-tolerance proteins by screening for cDNA clones that confer salt resistance when overexpressed. By this "cross-phylogenetic" screen, an A.thaliana gene was isolated encoding a glycine-rich protein, which was named AtGRP9. Overexpression of AtGRP9 in yeast cells led to significant increase in salt tolerance of the yeast strain. Northern blotting analysis revealed that AtGRP9 was expressed specifically in the roots of A.thaliana and was induced by NaCl. The growth of some transgenic plants was easily controlled by using the medium with different NaCl concentrations. Taken together, these results show that AtGRP9 may be involved in the salt stress response in A.thaliana.