Analysis of the promoter activity of a wheat dehydrin gene (DHN-5) under various stress conditions

A wheat dehydrin gene (DHN-5) is inducible by either treatment with abscisic acid (ABA) or by abiotic stress such as drought and salinity. To further investigate the regulation of the gene, a 1,128-bp genomic fragment upstream of the DHN-5 translated sequence has been isolated, cloned, and designated as the ''PrDHN-5'' promoter. Sequence analysis of PrDHN-5 revealed the presence of cis-regulatory elements which could be required for abiotic stress and ABA responsiveness. The PrDHN-5 promoter was fused to the β-glucuronidase (gusA) gene and the resulting construct was transferred into Arabidopsis thaliana (heterologous dicotyledonous system) and wheat (homologous monocot system). Histochemical assays of stably transformed Arabidopsis plants showed that PrDHN-5 is active in this heterologous system. The accumulation of gusA transcripts was up-regulated by salt, osmotic and ABA treatment. Histochemical assay in wheat embryos showed a staining in callus and younger leaves treated with various stress. Altogether, these results show that PrDHN-5 is an abiotic-stress-inducible promoter.