Wounding activates immediate early transcription of genes for ERFs in tobacco plants

We have previously demonstrated that cutting induces the rapid response of genes for ethylene-responsive transcription factors (ERFs) in leaf strips of tobacco, and that the induction was not interfered but enhanced in the presence of the protein synthesis inhibitor cycloheximide (CHX). In this study, we analyzed the expression of genes for ERFs in tobacco plants by injuring leaf tissues with a hemostat. The results verified that mechanical damage is a trigger for rapid and concurrent induction of both the local and the systemic expression of genes for ERFs in tobacco plants. Further studies on systemic response of ERF genes in response to different severity and position of the wound on a leaf suggested that a threshold value might exist for the magnitude of wound signal to induce systemic activation of these genes. Then, we examined expression of genes for ERFs by analysis in transgenic tobacco plants that harbored reporter genes in which the promoter of the gene for NsERF2, NsERF3 or NsERF4 was fused to a gene for beta-glucuronidase. The results suggested that the local and systemic accumulation of ERF mRNAs after wounding was primarily mediated by the rapid activation of transcription of the respective genes. In addition, we found that cycloheximide triggered rapid activation of genes for ERFs which might be mediated via activation of transcription of the genes for ERFs.