A Journey with Plant Cell Division: Reflection at My Halfway Stop

Abstract

I have studied various aspects of plant cell division for more than 40 years, and here I try to illustrate some foci among them. First, establishment of the induction of cell division in freshly isolated protoplasts from leaves is described, as this is important not only for biotechnology, but also for the cell cycle transition from G0 to S phase, whose importance has not been fully understood yet. The role of plant hormones, auxin and cytokinin, on this process has not been fully elucidated. Secondly, establishment of a model plant cell system of tobacco BY-2 cells and the high level of cell cycle synchrony achieved using this system is also an important theme for me. However, I will not go into details, but instead refer to the two recently published monographs edited by myself (Nagata T, Hasezawa S, Inze D, Biotechnology in agriculture and forestry, vol. 53, Tobacco BY-2 Cells. Springer, Berlin, 2004; Nagata T, Matsuoka K, Inze D, Biotechnology in agriculture and forestry, vol. 58. Tobacco BY-2 cells. From cellular dynamics to omics, Springer, Berlin, 2006). Further, habituation, discovered by Gautheret (Bull Soc Chim Biol 24:13–47, 1942), will be described, and I will describe how recently we have identified key molecules that may play an important role in this process. Finally, I will try to illustrate aspects of heterophylly from our studies on Ludwigia arcuata (Onagraceae). Although heterophylly is thought to be mostly related to cell elongation in leaves and induced by environmental cues, we found that in L. arcuata, it is closely associated with cell division. This system offers an opportunity to understand the role of cell division upon leaf shape determination as affected by environmental cues. Thus, as my scientific issues are always associated with cell division, their aspects and background stories will be described in this chapter.