Heterologous Expression of Dehydration-Inducible MfWRKY17 of Myrothamnus Flabellifolia Confers Drought and Salt Tolerance in Arabidopsis .

As the only woody resurrection plant,Myrothamnus flabellifoliahas a strong tolerance to drought and can survive long-term in a desiccated environment. However, the molecular mechanisms related to the stress tolerance ofM. flabellifoliaare largely unknown, and few tolerance-related genes previously identified had been functionally characterized. WRKYs are a group of unique and complex plant transcription factors, and have reported functions in diverse biological processes, especially in the regulation of abiotic stress tolerances, in various species. However, little is known about their roles in response to abiotic stresses inM. flabellifolia. In this study, we characterized a dehydration-inducibleWRKYtranscription factor gene,MfWRKY17, fromM. flabellifolia.MfWRKY17shows high degree of homology with genes fromVitis viniferaandVitis pseudoreticulata,belonging to group II of the WRKY family. Unlike known WRKY17s in other organisms acting as negative regulators in biotic or abiotic stress responses, overexpression ofMfWRKY17inArabidopsissignificantly increased drought and salt tolerance. Further investigations indicated thatMfWRKY17participated in increasing water retention, maintaining chlorophyll content, and regulating ABA biosynthesis and stress-related gene expression. These results suggest that MfWRKY17 possibly acts as a positive regulator of stress tolerance in the resurrection plantM. flabellifolia.