EN
In our previous study, 25 Hsf gene homologues were identified and analyzed in maize. However, the exact functions of these gene family members are unclear at present. Here, we report the isolation and characterization of a strongly heat-induced HsfA2 gene from maize, ZmHsf04, and show its function in the heat/salt-stress response. Subcellular location assays showed that the ZmHsf04 protein is localized to the nucleus. Transcription activation data demonstrate that an AHA2 domain protein is necessary for the transcriptional activity of ZmHsf04. Furthermore, the function of ZmHsf04 was characterized in detail in transgenic plants of Arabidopsis thaliana Col-0. Overexpression of ZmHsf04 in Arabidopsis enhanced thermotolerance and positively regulated short-term-acquired thermotolerance. In addition, ZmHsf04 significantly improved salt tolerance and increased the sensitivity to abscisic acid in transgenic Arabidopsis. Overexpression of ZmHsf04 in Col-0 plants significantly up-regulated the expression of heat-specific HSP genes (AtHsp25.3-P, AtHsp18.2-CI, and AtHsp70B) and stress-related genes (AtAPX2 and AtGolS1) compared to the wild type. In summary, we have characterized a transcriptional regulator, ZmHsf04, which has important functions in enhancing heat and salt tolerance in plants.