Dominant-negative form of bZIP-type transcription factor inhibits transdifferentiation of a differentiated leaf cell into a pluripotent stem cell in Physcomitrella patens

Abstract

Transdifferentiation from a differentiated cell to a pluripotent stem cell is frequently observed in plants, in contrast to the firmness of differentiated states in animals. A leaf cell of Physcomitrella patens begins apical growth and cell division after leaf excision and exposure to light within 24 hours and ultimately grows into a complete plant body. To identify the factors that promote transdifferentiation, we collected a time-course profile of gene expression by using custom-microarrays, and identified 29 transcription factors (TFs) that were significantly up-regulated within 12 hours in excised leaves. Next, we investigated whether these TFs are involved in transdifferentiation by dominant repression by conditionally overexpressing chimeric genes in which TFs are fused with a modified EAR-motif repression domain (SRDX). Overexpression of a bZIP TF SRDX fusion protein severely inhibited the transdifferentiation, indicating the bZIP TF is a potential promoting factor of transdifferentiation.