Functional characterization of a new maize heat shock transcription factor gene ZmHsf01 playing important roles in thermotolerance

Background. The yield of maize crop is influenced seriously by heat waves. Plant heat shock transcription factors (Hsfs) play a key regulatory role in heat shock signal transduction pathway. Method. In this study, a new heat shock transcription factor gene, ZmHsf01 (accession number: MK888854) , was cloned from maize young leaves using homologous cloning method. The transcriptional level of ZmHsf01 were detected by qRT-PCR in different tissues or under heat shock, abscisic acid (ABA) and hydrogen peroxide (H2O2) treatment. The transgenic yeast and Arabidopsis were used to study the gene function of ZmHsf01. Result. The coding sequence (CDS) of ZmHsf01 was 1176 bp and encoded a protein that consisted of 391 amino acids. The homologous analysis result showed that ZmHsf01 and SbHsfA2d had the highest protein sequence identity. Subcellular localization experiments demonstrated that ZmHsf01 is localized to the nucleus. ZmHsf01 was expressed in many maize tissues and was up-regulated by heat stress. ZmHsf01 was up-regulated in roots and down-regulated in leaves by ABA and H2O2treatments. In yeast, ZmHsf01-overexpressing cells showed increased thermotolerance. In Arabidopsis seedlings, ZmHsf01 complemented the thermotolerance defects of athsfa2 mutant and ZmHsf01-overexpressing lines presented enhanced basal and acquired thermotolerance. Compared to wild type (WT) seedlings, ZmHsf01-overexpressing lines showed increased chlorophyll content after heat stress. The expression level of heat shock protein genes was up-regulated higher in ZmHsf01-overexpressing Arabidopsis seedlings than that in WT. These results suggested that ZmHsf01 plays a vital role in plant response to heat stress.