Characteristics and Regulating Role in Thermotolerance of the Heat Shock Transcription Factor ZmHsf12 from Zea mays L.

Plant heat shock transcription factors (Hsfs) are important regulators of heat shock signal transduction pathway. There are 30 members of the Hsf family in maize, only two of which, ZmHsf06 and ZmHsf12 , belong to subclass A1. Our previous work demonstrated that ZmHsf06 -overexpressing Arabidopsis lines showed improved tolerance to heat and drought stresses. In this study, we isolated ZmHsf12 from young leaves of maize ( Zea mays L.) using homologous cloning methods. The CDS (coding sequence) of ZmHsf12 is 1,494 bp and encodes a putative protein consisting of 497 amino acids which possesses domains such as DBD (DNA-binding domain), OD (oligomerization domain), NLS (nuclear localization signal), NES (nuclear export signal), and an AHA (activator) motif. The ZmHsf12-GFP fusion protein is localized to the cell nucleus. ZmHsf12 was expressed in many maize organs, and its expression was up-regulated by heat shock. Furthermore, we characterized the function of ZmHsf12 in yeast and Arabidopsis. Yeast cells overexpressing ZmHsf12 showed enhanced heat tolerance. ZmHsf12 -overexpressing Arabidopsis seedlings displayed significant increases in both basal and acquired thermotolerance. Compared to WT seedlings, the ZmHsf12 -overexpressing lines displayed both increased chlorophyll contents and higher survival rates. Also, the expression of AtHsps was increased higher in the ZmHsf12 -overexpressing Arabidopsis lines after heat stress. The results of our study strongly suggested that ZmHsf12 may take part in plant response to heat stress.