Arabidopsis HRE1α, a splicing variant of AtERF73/HRE1, functions as a nuclear transcription activator in hypoxia response and root development

HRE1 alpha shows transcriptional activation activity in its C-terminal region via GCC box but not DRE/CRT and plays an important role in root development via root meristem cell division regulation. AtERF73/HRE1 protein, a member of the Arabidopsis AP2/ERF family, contains a conserved AP2/ERF DNA-binding domain. Here, we studied the molecular function of HRE1 alpha, a splicing variant of AtERF73/HRE1, as well as its role in root development. HRE1 alpha-overexpressing transgenic plants (OXs) showed tolerance to submergence. HRE1 alpha showed transcriptional activation activity via GCC box but not DRE/CRT. The 121-211 aa region of HRE1 alpha was responsible for the transcriptional activation activity, and the region was conserved among homologs of other species but was not found in other Arabidopsis proteins. HRE1 alpha OXs showed increased primary root length due to elevated root cell division. Our results suggest that HRE1 alpha functions as a transcription activator in the nucleus, and plays an important role in root development through regulation of root meristem cell division.