The wheat ERF transcription factor TaPIE1 mediates host responses to both the necrotrophic pathogen Rhizoctonia cerealis and freezing stresses

PLANT PHYSIOLOGY, doi: 10.1104/pp.113.229575

The wheat ERF transcription factor TaPIE1 mediates host responses to both the necrotrophic pathogen Rhizoctonia cerealis and freezing stresses

Xiuliang Zhu1, Lin Qi1, Xin Liu1, Shibin Cai2, Huijun Xu1, Rongfeng Huang3, Jiarui Li4, Xuening Wei1 and Zengyan Zhang

Abstract

Sharp eyespot disease (primarily caused by the pathogen Rhizoctonia cerealis) and freezing stress are important yield limitations for the production of wheat (Triticum aestivum L.). Here, we reported the new insights into the function of an ethylene response factor (ERF) in wheat, namely TaPIE1, in host responses to pathogen Rhizoctonia cerealis and freezing stresses and the mechanisms underlying the functions. TaPIE1-overexpressing transgenic wheat exhibited significantly enhanced resistance to both R. cerealis and freezing stresses, whereas TaPIE1-underexpressing wheat plants were more susceptible to both stresses relative to control plants. Following both stress treatments, electrolyte leakage and the H2O2 content were significantly reduced, and both the proline and soluble sugar contents were elevated in TaPIE1-overexpressing wheat, whereas these physiological traits in TaPIE1-underexpressing wheat exhibited the opposite trend. Microarray and qRT-PCR analyses of TaPIE1-overexpressing and underexpressing wheat plants indicated that TaPIE1 activated a subset of defense- and stress-related genes. Assays of the electrophoretic mobility shift and transient expression in tobacco showed that the GCC-boxes in the promoters of TaPIE1-activated genes were essential for transactivation of TaPIE1. The transactivation activity of TaPIE1 and the expression of TaPIE1-activated defense- and stress-related genes were significantly elevated following R. cerealis, freezing, and exogenous ethylene treatments. TaPIE1-mediated resistance to R. cerealis and freezing were positively modulated by ethylene. These data suggest that TaPIE1 positively regulates the defense responses to R. cerealis and freezing stresses by activating defensive and stress-related genes downstream of the ethylene signaling pathway and by modulating related physiological traits in wheat.