A novel ERF transcription activator in wheat and its induction kinetics after pathogen and hormone treatments

In this study, a pathogen-inducible ERF (ethylene-response factor) gene in wheat, designated TaERF3, was isolated and characterized in detail. The sequence of the TaERF3 protein possesses all of the traits commonly associated with ERFs, but its entire sequence shares low identity with other ERFs of transcription factor families. The results of assays on subcelluar localization, GCC box-binding ability, and transactivation activity indicated that TaERF3 is a nuclear targeting protein and functions as a GCC box-binding transcriptional activator. Following infection with Blumeria graminis, the induction peak of TaERF3 expression occurring at 12 h in the resistant line was about six times higher than that in its susceptible parent. Following infections with Fusarium graminearum or Rhizoctonia cerealis, the TaERF3 maximum inductions in the susceptible line occurring at 12 h were about three or six times higher than those in the resistant lines, whereas after 24 h or 48 h, the transcript inductions in the resistant lines were much higher than that in the susceptible line. Furthermore, the TaERF3 transcript peak induced by salicylic acid (SA) treatment occurred at 4 h, whereas the peaks induced by exogenous ethylene and methyl jasmonate (MeJA) occurred at 24 h, all of which were earlier than those induced by pathogens in the resistant lines. These results suggested that TaERF3 might be mainly involved in the active defence response to B. graminis at an earlier stage through SA signalling, and to F. graminearum and R. cerealis at a later stage through the ethylene/jasmonic acid signalling pathways.