Prof. Jan Lohmann Stammzellbiologie
The Stem Cell Biology department focuses on the mechanisms that regulate the identity, number and division activity of plant stem cells. We pursue an integrated research program using the latest methods of genetics, genomics, biochemistry, molecular biology, and microscopy flanked by computer-aided data analysis and modeling. Our goal is to decipher the genetic regulatory circuits that control stem cell activity in response to developmental stage and environmental stimuli in the reference plant Arabidopsis thaliana.
Regulatory networks of stem cell control in the reference plant Arabidopsis
Few scientific topics currently attract as much attention as stem cells. While public debate has focused on embryonic stem cells from animals and humans, stem cells are common to all multicellular organisms. In most animals, the only “true” totipotent stem cell is the fertilised egg and its immediate descendants. Plant stem cells, in contrast, continue to be totipotent and active throughout the plant’s life, allowing the individual to grow and develop over many years.
Plant stem cells reside at the growing points of a plant, namely the root tip and the shoot apex and are embedded into specialised structures called meristems, which provide a local environment that regulates the homeostasis between proliferation and differentiation. Plant cells are surrounded by a cell wall and are hence immobile; growth and morphogenesis in plants therefore rely on the highly controlled interplay of cell division and cell expansion. These processes are regulated by local as well as mobile factors, including plant hormones, and the integration of these pathways brings about the controlled development of complex tissues. Our lab is aiming to decipher the mechanisms underlying these processes using state of the art methodology:
Current research question of the lab:
- How is stem cell fate initiated and maintained in the shoot apical meristem?
- How are local transcriptional signals integrated with system wide hormonal signals to synchronize stem cell behaviour with the growth status of the entire plant?
- How are environmental signals sensed and relayed to modulate meristem activity?
- How to genes act together to build complex tissues?
Since the activity of the shoot meristem is controlled by a large number of factors, which cannot be studied in detail by a single group, we focus our analyses on four essential components of the regulatory network. First, we study the activity of the homeodomain transcription factor WUSCHEL (WUS) on a mechanistic basis, since WUS is essential for stem cell induction and maintenance. These experiments include the cell type specific identification of direct and indirect target genes, as well as the functional characterization of these factors. Second, we record the epigenetic states of various cell types of the meristem, including stem cells to gain a detailed understanding of their molecular identities. Third, we examine the interaction of cytokinin and auxin plant hormone signaling pathways with the core meristem regulation machinery provided by WUS. And fourth, we study the role of of environmental signals, such as daylenght and temperature, in modulating the activity of stem cells of the shoot apical meristem and investigate how mechanisms of short-trem acclimatization converge with long-term adaptation using natural genetic variation.
Jan Lohmann is a member of EMBO and has received a number of awards including the research price of Heidelberg University, the presidents medal of the Society of Experimental Biology, the EMBO Young Investigator award and the HFSP carereer development award.
Our work is supported by funds from a variety of public sources, including the DFG and the ERC.
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