Abstract
Callus is a mass of dedifferentiated cells and is often formed in the wounded tissue during healing processes. Although phytohormone auxin and cytokinin have been shown to be tightly involved in callus formation, regulator(s) that induces and/or maintain the dedifferentiated state has not identified yet. DNA microarray analysis between differentiated and dedifferentiated tissues of Arabidopsis identified a gene for the plant specific transcription factor of AP2/ERF family that was upregulated in the dedifferentiated cell lines (Iwase et al., 2005). Interestingly, promoter-reporter analysis showed this gene was up-regulated at wound site of tissues. In addition, ectopic expression of the gene induced callus formation in the shoot, hypocotyl and root in Arabidopsis. This callus grew and maintained dedifferentiation state in the phytohormone-free medium. We discuss the possible function of the transcription factor in the regulation of callus formation in related to wound and phytohormone response.
