Seminář: Ondřej Smetana Ph.D.
od 15:00 do 16:30
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Location and activity of cambial stem cells in the Arabidopsis root
(Institute of Biotechnology, University of Helsinki, Finland)
Vascular cambium is a secondary meristem producing xylem and phloem along thickening plant organs. Despite the importance of vascular cambium in plant biology and in wood production, the molecular and cellular mechanisms underlying cambial activity remain largely unknown. Particularly, it is unknown where the cambial stem cells are located, and how the stem cell niche is organized to drive cambial growth.
In animal stem cell studies lineage tracing has been the method for locating the stem cells. In this method single cell clones marked with reporter expression are generated within a population of dividing cells. The clones are transmitted to all daughter cells of the initial cell, resulting in a marked sector within the tissue. By analysing the size and distribution of the sectors the position and the mitotic activity of dividing cells and stem cells can be deduced.
In order to understand the cell lineage relations in the Arabidopsis root cambium, we generated GUS/GFP sectors by using two step CRE-lox based clonal activation system. To understand which cells in the primary tissue contribute to the cambium formation, we induced single cell clones during the primary development of the root and analysed the growing sectors during the secondary development. We also generated marked sectors in active cambium to map the position of stem cells and to understand the growth dynamics of the cambial cells. Our analysis revealed that cambium originates from cells adjacent to existing xylem, thus suggesting that xylem has critical role in positioning the cambial stem cell niche. In my presentation I will also explain our approach to identify the molecular players in this process.