Stem cells

The meristems at the growing tips of roots and shoots contain stem cells and their immediate progeny, so-called transit amplifying cells.  The progression from stem cells to differentiated cells that transient amplifying cells undertake is a gradual process: involving an initial phase of rapid cell divisions followed by the extinction of proliferation at the meristem boundary.  

Nonetheless, a modified cell cycle persists in these post-mitotic cells, manifested by several rounds of genome duplication (endoreplicating cells) that proceed concomitantly with cellular differentiation. Mitotic exit is of great importance for plant growth control: in plants that experience environmental stress, cells prematurely lose the capacity to divide, thereby reducing growth capacity, and hence, recovery following a stress episode.  Likewise, such differentiated plant cells in general lack the capacity to resume proliferation, and therefore cells that express the metabolic networks for the production of high value chemicals (bio-active compounds cannot be cultivated. This is because most cultured plant cells lose their differentiation state (which is critical for their ability to produce bio-active compounds) rapidly.  

We are interested to identify the mechanisms by which the differentiated state is reversed (reprogrammed) in regenerating plants and what the impediments are to proliferation in differentiated cells. We have developed new tools to isolate and enrich plant protoplasts, and are studying the mechanisms of de-differentiation with the aim to use plant cells in the future as the basis for a new biotechnological industry.