Characterisation of an SKn-type Dehydrin Promoter from Wheat and Its Responsiveness to Various Abiotic and Biotic Stresses

Dehydrins (DHNs; late embryogenesis abundant D11 family) are a family of intrinsically unstructured plant proteins that accumulate in seed embryos or in vegetative tissues in response to environmental stresses. To elucidate the regulatory mechanisms of wheat-derived DHNs under these stresses, we isolated and characterised the full-length cDNA, genomic and promoter sequences of dehydrin wzy1-2 (SK3-type) from the wheat (Triticum aestivum L.) Zhengyin 1. We then analysed the responsiveness of the wzy1-2 promoter to various abiotic and biotic stresses. The sequence analysis indicated that the gene is 1,255 bp long and contains one 103-bp intron, which is inserted in the nucleotide sequence encoding the S-motif and characterised by a GT-AG border. The promoter contains several potential stress-related cis-acting regulatory elements, including ABA-, dehydration-, low temperature-, methyl jasmonate (MeJA)-, gibberellin (GA)-, salicylic acid (SA)-, and defence and stress-responsive elements. The quantitative PCR analysis demonstrated that the transcript accumulation occurred in response to osmotic stress, cold, MeJA, abscisic acid (ABA), GA and SA treatments. The histochemical analysis of GUS expression in wheat transgenic calli demonstrated that wzy1-2 promoter activity could be upregulated by osmotic stress, ABA, GA or SA treatment. Quantitative fluorometric GUS assays further demonstrated that one SA-responsive element was located between -59 and -39 bp and that one GA-responsive element was situated between -39 and +107 bp. Combined, these results indicate that multiple cis-acting elements are involved in the induction of the wzy1-2 gene, which implies that different cis-acting elements interact in stress response cross-talk.