Abstract
The molecular mechanisms of transdifferentiation from mature somatic cells to stem cells are largely unexplored in both plants and animals. The moss Physcomitrella patens has a remarkable capacity for such transdifferentiation.
In normal development of the moss, a spore germinates to produce a protonemal apical cell, a type of stem cells. Subsequently, the apical cell changes its nature and raises a leafy shoot, gametophore. Meanwhile, in dissected leaves, cells facing to cutting surface are transdifferentiated into protonemal apical cells. We established an experimental system in which this transdifferentiation can be synchronously induced at high frequency. We further investigated the involvement of phytohormones in this process. Exogenous auxin or abscisic acid at an excess concentration inhibited the transdifferentiation, while cytokinin, gibberellin, or brassinosteroid did not. The suppression of the transdifferentiation by antiauxin was specifically restored by exogenous auxin. Thus, intrinsic auxin accumulation with proper concentration is necessary for this process.
