Abstract
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.
Highlights
Maize (Zea mays L.) is one of the most important food crops in the world
The deduced ZmERF105 protein contains a conserved AP2/ethylene response factor (ERF) domain consisting of 58 amino acids, with conserved alanine (A) and aspartic acid (D) in it, suggesting that it is a member of the ERF family (Figure 1)
To further confirm whether the role of ZmERF105 in resistance against E. turcicum is related to superoxide dismutase (SOD) and PDD activities, we examined the activities of SOD and POD in ZmERF105 overexpression and erf105 mutant lines
Summary
Maize (Zea mays L.) is one of the most important food crops in the world. Its productivity is frequently hampered by pathogens and so improved disease resistance is an important goal in many breeding projects (Galiano-Carneiro and Miedaner, 2017; Weems and Bradley, 2018). Northern corn leaf blight (NCLB), caused by Exserohilum turcicum (E. turcicum), is a destructive disease of maize worldwide (Chang and Fan, 1986). It can reduce crop yields approximately 50%, severe infection even results in a total yield loss (Raymundo and Hooker, 1981; Perkins and Pedersen, 1987). Qualitative resistance often results in breakdown of disease resistance because of a change in the pathogen population; quantitative resistance breeding has become the primary method for NCLB control (Carson, 1995; Welz and Geiger, 2000). It is necessary to isolate resistance genes and analyze their funtions in order to improve maize resistance to E. turcicum
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