Abstract
A callus can be considered as one of the phenotypes of the plant cells. There may be factors that induce and/or maintain the dedifferentiated state. To identify such factors, we performed comparative analyses of the gene expression profiles by DNA microarray between Arabidopsis seedlings and three callus lines, and found that a gene for the plant specific transcription factor of AP2/ERF family was upregulated in callus. Transgenic plants that express the gene under the control of 35SCaMV promoter showed morphology alteration. Transformants with severe phenotype formed callus in the shoot, hypocotyl and root. These callus generated from the transformants grew and maintained dedifferentiation state in the phytohormone-free medium. The seedlings of T2 generation can dedifferentiate into callus under the lower concentration of auxin, in which condition wild type seedlings do not form callus. We discuss the possible function of the transcription factor in the regulation of callus formation.*
