April 5, 2024
Hosted By Muhammad Numan
The shoot apical meristem (SAM) gives rise to above-ground organs. The size of the SAM is relatively constant due to the balance of stem cell replenishment versus cell recruitment into forming organs. In angiosperms, the transcription factor WUSCHEL (WUS) promotes stem identity in the central zone of the SAM. WUS forms a negative feedback loop with a signaling pathway activated by CLAVATA3 (CLV3). In the periphery of the SAM, the ERECTA family (ERf) receptors promote cell differentiation and constrain the expression of WUS and CLV3. Here, we show that four ligands of ERfs redundantly inhibit CLV3 and WUS expression. The transcriptome analysis confirmed that WUS and CLV3 are the main targets of ERfs signaling and uncovered several new ones. Analysis of promoter reporters on 3D images indicated that in the vegetative meristem, the WUS expression domain mostly overlapped with the CLV3 domain and did not shift along the apical-basal axis in clv3. The 3D mathematical model reproduced experimentally observed CLV3 and WUS expression patterns with fewer assumptions compared to earlier models. Based on these findings, we propose that CLV3 regulates WUS cellular level through autocrine signaling, while ERfs regulate WUS spatial expression, preventing its encroachment into the peripheral zone.