Photoperiod, temperature and water deficit differentially regulate the expression of four dehydrin genes from Eucalyptus globulus

During the last few years, considerable effort has been directed toward understanding how Eucalyptus globulus responds and adapts to low temperature due to its low freezing resistance, especially through gene expression analysis. A recent study has confirmed that freezing stress induces the expression of three dehydrin (DHN) genes in E. globulus. This work reports the identification of a new YSK-type DHN gene in E. globulus (EuglDHN3) and examines the responses of this gene and the three previously reported (EuglDHN1, EuglDHN2 and EuglDHN10) under low temperature (LT), short photoperiod and water deficit (WD) in one sensitive and one freezing-resistant genotype of E. globulus, to assign them to a class: low temperature responsive, photoperiod responsive or water deficit responsive. Results indicated that two SKn-type DHNs (EuglDHN1 and EuglDHN2) were strongly induced by LT and WD, the KS-type DHN (EuglDHN10) was strongly induced by LT and the YnSKn-type by WD. The expression patterns under LT and WD were consistent with the regulatory elements identified in the promoter regions of the four DHN genes. The differential accumulation of EuglDHN1, EuglDHN2 and EuglDHN3 transcripts suggests a differential regulation in specific tissues under WD, and EuglDHN1 and EuglDHN10 under LT.