title: A dynamic reciprocal RBR-PRC2 regulatory circuit controls Arabidopsis gametophyte development.
abstract: Unlike animals that produce gametes upon differentiation of meiotic products, plants develop haploid male and female gametophytes that differentiate gametes such as sperm, egg and central cells, and accessory cells [1, 2]. Both gametophytes participate in double fertilization and give rise to the next sporophytic generation. Little is known about the function of cell-cycle genes in differentiation and development of gametophytes and in reproduction [1, 2]. RETINOBLASTOMA RELATED (RBR) is a plant homolog of the tumor suppressor Retinoblastoma (pRb), which is primarily known as negative regulator of the cell cycle [3]. We show that RBR is required for cell differentiation of male and female gametophytes in Arabidopsis and that loss of RBR perturbs expression levels of the evolutionarily ancient Polycomb Repressive Complex 2 (PRC2) subunits and their modifiers encoding PRC2 subunits or DNA METHYLTRANSFERASE 1 (MET1) [4-6], exemplifying convergent evolution involving the RBR-PRC2-MET1 regulatory pathways. In addition, RBR binds MET1, and maintenance of heterochromatin in central cells, a mechanism that is likely mediated by MET1[7, 8], is impaired in the absence of RBR. Surprisingly, PRC2-specific H3K27-trimethylation activity represses paternal RBR allele, suggesting a functional role for a dynamic and reciprocal RBR-PRC2 regulatory circuit in cellular differentiation and reproductive development.
authors.affiliation: Plant Biotechnology, Institute of Plant Sciences & Zurich-Basel Plant Science Center, ETH Zurich, Universitätstrasse 2, CH-8092 Zurich, Switzerland.
authors.forename: Amal J
authors.initials: AJ
authors.lastname: Johnston
authors.forename: Elena
authors.initials: E
authors.lastname: Matveeva
authors.forename: Olga
authors.initials: O
authors.lastname: Kirioukhova
authors.forename: Ueli
authors.initials: U
authors.lastname: Grossniklaus
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Gruissem
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D006570:Heterochromatin / Q000378:metabolism; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D006570:Heterochromatin; D063146:Polycomb-Group Proteins; C487568:RBR1 protein, Arabidopsis; D012097:Repressor Proteins