GIF Transcriptional Coregulators Control Root Meristem Homeostasis

ERCOLI F; PERRONE, AP; DEBERNARDI, JM; PALATNIK, J.F.; FERELA, A; RODRIGUEZ, R E

PLANT CELL

AMER SOC PLANT BIOLOGISTS

Lugar: Rockville; Año: 2018 vol. 30 p. 347 - 359

1040-4651

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 ofstem cells, which are referred to as transit-amplifying cells, undergo additional rounds of cell division prior to differentiation. Here,we describe the functions of GRF-INTERACTING FACTORs (GIFs), including ANGUSTIFOLIA3 (AN3), in Arabidopsis thaliana roots.GIFs have been shown to interact with GRF transcription factors and SWI/SNF chromatin remodeling complexes. We found thatcombinations of GIF mutants cause the loss of QC identity. However, despite their QC impairment, GIF mutants have a significantlyenlarged root meristem with additional lateral root cap layers. We show that the increased expression of PLETHORA1 (PLT1)is at least partially responsible for the large root meristems of an3 mutants. Furthermore, we found that GIFs are necessaryfor maintaining the precise expression patterns of key developmental regulators and that AN3 complexes bind directly to thepromoter regions of PLT1 as well as SCARECROW. We propose that AN3/GIFs participate in different pathways that controlQC organization and the size of the meristem.