Timing Mechanism Dependent on Cell Division Is Invoked by Polycomb Eviction in Plant Stem Cells

• Published in: Science (American Association for the Advancement of Science) Vol. 343; no. 6170; p. 505
• Main Authors: Sun, Bo, Looi, Liang-Sheng, Guo, Siyi, He, Zemiao, Gan, Eng-Seng, Huang, Jiangbo, Xu, Yifeng, Wee, Wan-Yi, Ito, Toshiro
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 31.01.2014; The American Association for the Advancement of Science
• Subjects: AGAMOUS Protein, Arabidopsis - genetics; AGAMOUS Protein, Arabidopsis - metabolism; Arabidopsis - cytology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Base Sequence; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell division; Cell Division - genetics; Cell Division - physiology; Cellular biology; Developmental Programs; Epigenesis, Genetic; Flowers - cytology; Flowers - genetics; Flowers - growth & development; Gene Expression Regulation, Plant; Individualized Instruction; Logical Thinking; Meristem - cytology; Molecular Sequence Data; Plant biology; Plants, Genetically Modified - cytology; Plants, Genetically Modified - growth & development; Polycomb-Group Proteins - genetics; Polycomb-Group Proteins - metabolism; Promoter Regions, Genetic; Proteins; RESEARCH ARTICLE SUMMARY; Stem cells; Stem Cells - cytology; Time Factors; Trans-Activators - genetics; Trans-Activators - metabolism
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1248559

Plant floral stem cells divide a limited number of times before they stop and terminally differentiate, but the mechanisms that control this timing remain unclear. The precise temporal induction of the Arabidopsis zinc finger repressor KNUCKLES (KNU) is essential for the coordinated growth and differentiation of floral stem cells. We identify an epigenetic mechanism in which the floral homeotic protein AGAMOUS (AG) induces KNU at ~2 days of delay. AG binding sites colocalize with a Polycomb response element in the KNU upstream region. AG binding to the KNU promoter causes the eviction of the Polycomb group proteins from the locus, leading to cell division-dependent induction. These analyses demonstrate that floral stem cells measure developmental timing by a division-dependent epigenetic timer triggered by Polycomb eviction.