A Novel ERF Transcription Factor, ZmERF105, Positively Regulates Maize Resistance to Exserohilum turcicum

The ethylene response factor (ERF) plays a crucial role in plant innate immunity. However, the molecular function of ERF in response to Exserohilum turcicum ( E . turcicum ) remains unknown in maize. In this study, a novel ERF gene, designated as ZmERF105 , was firstly isolated and characterized. The ZmERF105 protein contains an APETALA2/ETHYLENE RESPONSIVE FACTOR (AP2/ERF) domain and a conserved LSPLSPHP motif in its C-terminal region. ZmERF105 protein was exclusively localized to the nucleus. ZmERF105 expression responded to E . turcicum treatment. Yeast one-hybrid and transcription activity assays revealed that ZmERF105 is an activator of transcription and binds to GCC-box elements. Over-expression of ZmERF105 was shown to increase maize resistance against E . turcicum , and erf105 mutant lines displayed opposite phenotype. Moreover, the activities of superoxide dismutase (SOD) and peroxidase (POD) in the ZmERF105 over-expression lines were markedly higher than in the wild-type maize lines (WT) after infection with E . turcicum , and were compromised in the erf105 mutant lines. Simultaneously, ZmERF105 over-expression lines enhanced the expression of several pathogenesis-related (PR) genes, including ZmPR1a , ZmPR2 , ZmPR5 , ZmPR10.1 , and ZmPR10.2 after infection with E . turcicum . In contrast, the expression of PR genes was reduced in erf105 mutant lines. Our work reveals that ZmERF105 as a novel player of the ERF network and positively regulates the maize resistance response to E . turcicum .