Induction of PLT1, PLT3, PLT4, PLT5 and PLT7 in whole seedlings

Organ formation in animals and plants relies on precise control of cell state transitions to turn stem cell daughters into fully differentiated cells. In plants, cells cannot rearrange due to shared cell walls. Thus, differentiation progression and the accompanying cell expansion must be tightly coordinated. PLETHORA (PLT) transcription factor gradients were shown to guide the progression of cell differentiation at different positions in the Arabidopsis root. While well-described transcription factor gradients in animals specify distinct cell fates within an essentially static context, the PLT gradient is unique in its ability to control cell differentiation in a growing organ during continuous production and expansion of cells. To understand the output of these gradients we studied the gene set transcriptionally controlled by PLTs. Our work reveals how the PLT gradient regulates cell state by region-specific induction of cell proliferation genes and repression of differentiation. Moreover, PLT targets include major patterning genes and autoregulatory feedback components, reinforcing their role as master regulators of organ development.