Integration of Transcriptional Repression and Polycomb-Mediated Silencing of WUSCHEL in Floral Meristems

• Published in: The Plant cell Vol. 31; no. 7; pp. 1488 - 1505
• Main Authors: Sun, Bo, Zhou, Yingying, Cai, Jie, Shang, Erlei, Yamaguchi, Nobutoshi, Xiao, Jun, Looi, Liang-Sheng, Wee, Wan-Yi, Gao, Xiuying, Wagner, Doris, Ito, Toshiro
• Format: Journal Article
• Language: English
• Published: England American Society of Plant Biologists 01.07.2019
• Subjects: Arabidopsis - genetics; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Carrier Proteins - genetics; Carrier Proteins - metabolism; Chromatin - metabolism; Epigenesis, Genetic; Epistasis, Genetic; Flowers - genetics; Gene Expression Regulation, Plant; Gene Silencing; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Meristem - genetics; Models, Biological; Polycomb-Group Proteins - metabolism; Promoter Regions, Genetic - genetics; Protein Binding; Repressor Proteins - metabolism; Transcription, Genetic
• DOI: 10.1105/tpc.18.00450
• ISSN: 1040-4651

Arabidopsis ( ) floral meristems terminate after the carpel primordia arise. This is achieved through the temporal repression of ( ), which is essential for stem cell maintenance. At floral stage 6, is repressed by KNUCKLES (KNU), a repressor directly activated by AGAMOUS. KNU was suggested to repress through histone deacetylation; however, how the changes in the chromatin state of are initiated and maintained to terminate the floral meristem remains elusive. Here, we show that KNU integrates initial transcriptional repression with polycomb-mediated stable silencing of After KNU is induced, it binds to the promoter and causes eviction of SPLAYED, which is a known activator of and can oppose polycomb repression. KNU also physically interacts with FERTILIZATION-INDEPENDENT ENDOSPERM, a key polycomb repressive complex2 component, and mediates the subsequent deposition of the repressive histone H3 lysine 27 trimethylation for stable silencing of This multi-step silencing of leads to the termination of floral stem cells, ensuring proper carpel development. Thus, our work describes a detailed mechanism for heritable floral stem cell termination in a precise spatiotemporal manner.