Root stem cell controller identified Scientists have investigated how a certain gene controls stem cell differentiation in plant roots. Health © Thinkstock Plant stem cells are found in the growing tips of shoots and roots. In roots, stem cell differentiation into distinct cell types is controlled by the quiescent centre (QC). A gene called Wuschel-related Homeobox 5 (WOX5) is expressed specifically in the QCs of plant roots, and plays an important role in stem cell differentiation. The EU-funded 'Gene regulatory network controlling the root stem cell niche in Arabidopsis thaliana' (STEM CELL REGULATION) project investigated how WOX5 controls this process. Earlier research has shown that when WOX5 is not active, the QC loses control of nearby stem cells, leading to stem cell differentiation. Thus, STEM CELL REGULATION used advanced molecular biology techniques to identify which genes are switched on and off by WOX5 activity. Researchers identified several genes that WOX5 binds to, which indicates that WOX5 controls their expression in some way. These were confirmed using an independent method, and then selected for further study. Repression of many of WOX5's gene targets is required for the QC to function correctly by maintaining stem cell populations in an undifferentiated state. This suggests that WOX5 plays a crucial role in maintaining the status quo in growing roots. Keywords Plant roots, stem cell differentiation, quiescent centre, Wuschel-related Homeobox 5
