GIF Transcriptional Coregulators Control Root Meristem Homeostasis.

In the root meristem, the quiescent center (QC) is surrounded by stem cells, which in turn generate the different cell types of the root. QC cells rarely divide under normal conditions but can replenish damaged stem cells. In the proximal meristem, the daughters of stem cells, which are referred to as transit-amplifying cells, undergo additional rounds of cell division prior to differentiation. Here, we describe the functions of (), including (), in roots. GIFs have been shown to interact with GRF transcription factors and SWI/SNF chromatin remodeling complexes. We found that combinations of mutants cause the loss of QC identity. However, despite their QC impairment, mutants have a significantly enlarged root meristem with additional lateral root cap layers. We show that the increased expression of () is at least partially responsible for the large root meristems of mutants. Furthermore, we found that GIFs are necessary for maintaining the precise expression patterns of key developmental regulators and that AN3 complexes bind directly to the promoter regions of as well as We propose that AN3/GIFs participate in different pathways that control QC organization and the size of the meristem.