[초청강연] Totipotency and Cellular Reprogramming in Plants

Totipotency and Cellular Reprogramming in Plants

Yoo-Sun Noh

Research Center for Plant Plasticity & School of Biological Sciences, Seoul National

University, Seoul 08826, Korea

Throughout their life cycle, plants must cope with environment where they
germinated and withstand challenges that threaten their survival. To confront such challenges,
plants have equipped themselves with high regenerative potential and developmental
plasticity which allow them to regenerate lost parts or even whole organism upon damage and
rapidly adjust developmental programs depending on environmental cues. These unique
abilities of plants are believed to be compensation mechanisms for the lack of mobility. The
regenerative potential of plants is highlighted by totipotency of which the molecular basis
remains obscure.
De novo regeneration of shoots can be achieved in vitro using a two-step process that
involves the acquisition of pluripotency on callus-induction media and the formation of de
novo shoots on shoot-induction media. We have recently reported that the histone
acetyltransferase HAG1/AtGCN5 provides an epigenetic platform for the transcriptional
activation of several root-meristem genes including WOX5, WOX14, SCR, PLT1, and PLT2 in
callus and the transcription factors encoded by these genes act as key potency factors
conferring competence for de novo shoot regeneration.
Although self-renewal and potency to differentiate upon proper signal-perception are
the two properties that define pluripotent cells, molecular mechanisms controlling the self-
renewal and pluripotency of callus cells and a link between the two properties are yet to be
elucidated. In this presentation, I will show that either excess or insufficient activities of cell
proliferation hinder callus pluripotency and thus result in poor de novo shoot regeneration.
Further, this cell-proliferation control of cellular pluripotency is linked to the expression of
key potency genes. These results demonstrate that pluripotency in callus is ensured by an
adequate level of cell proliferation and suggest a novel link between cell proliferation and the
acquisition of cellular pluripotency.