KNUCKLES terminates floral stem cell maintenance in Arabidopsis by directly repressing WUSCHEL through recruitment of polycomb group proteins

• Main Author: Vong, Silvia
• Other Authors: Toshiro Ito
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Science
• Online Access: http://hdl.handle.net/10356/49287
• Institution: Nanyang Technological University

In every Arabidopsis flower, the transition from the floral meristem (FM) to terminally differentiated floral organs is temporally regulated to ensure that the right numbers of floral organs form. At stage 6 of floral development, the homeotic gene AGAMOUS (AG) represses the stem cell establisher WUSCHEL (WUS) in the FM through KNUCKLES (KNU), a C2H2-type zinc-finger protein that contains a C-terminal EAR-like repression motif. The WUS locus at this stage also becomes covered with H3K27me3 repressive marks by the action of Polycomb Group (PcG) proteins. However, how the PcG is recruited to the WUS locus to deposit H3K27me3 marks is not known. We propose that KNU, which binds to WUS promoter, functions to recruit PcG through one of its components, FERTILIZATION INDEPENDENT ENDOSPERM (FIE). Here we show that WUS is ectopically expressed in FIE- silenced plants and that KNU and FIE are able to interact in vitro and in planta. This study thus suggests a model linking KNU and PcG proteins in the regulation of the FM stem cells.