Poster abstracts
Poster number 7 submitted by Natalie Deans
Paramutation at the maize pl1 locus is manifest by a developmentally-essential CHD3 nucleosome remodeler
Natalie C. Deans (Department of Molecular Genetics, Centers for Applied Plant Sciences and RNA Biology, The Ohio State University, Columbus, OH), Brian Giacopelli (Department of Molecular Genetics, The Ohio State University, Columbus, OH), Charles A. Addo-Quaye (Department of Biochemistry, Purdue University, West Lafayette, IN; Division of Natural Sciences & Mathematics, Lewis-Clark State College, Lewiston, ID), Brian P. Dilkes (Department of Biochemistry, Purdue University, West Lafayette, IN), Jay B. Hollick (Department of Molecular Genetics, Centers for Applied Plant Sciences and RNA Biology, The Ohio State University, Columbus, OH)
Abstract:
In maize, paramutations result in directed and meiotically-heritable regulatory changes of certain purple plant1 alleles1 which encode a R2R3 MYB protein required for anthocyanin production2. A strongly-expressed Pl1-Rhoades allele is suppressed in trans when combined with a transcriptionally and post-transcriptionally repressed Pl1-Rhoades allele (denoted Pl´ ), and both alleles are sexually transmitted in a repressed state. Mutant screens have identified at least sixteen loci whose functions are required to maintain repression (rmr) of Pl´ 3, 4. All known RMR proteins mediate 24 nucleotide (24nt) RNA biogenesis4, 5, 6, 7, 8, and four are putative orthologs of Arabidopsis proteins that facilitate repressive chromatin modifications. Here we introduce four ems-derived recessive alleles defining the rmr12 locus. Unlike other rmr-type mutations found to date4, 5, 7, 8, 9, 10, rmr12 mutants display a unique set of leaf, inflorescence, and pollen defects that highlight a novel mechanistic connection between paramutation and developmental gene control. We used position-based cloning to discover that rmr12 encodes a chromodomain helicase-DNA binding3 (CHD3) protein whose closest Arabidopsis ortholog, PICKLE, influences nucleosome homeostasis11, 12 presumably through its ability to translocate nucleosomes along a DNA substrate13. Genetic data indicates that RMR12 is not responsible for maintaining the epigenetic feature typifying pl1 paramutation thus leading to models in which RMR12 manifests repression through altering nucleosome / DNA interactions in response to a meiotically-heritable feature.
References:
1 Hollick et al. 1995 Genetics 141, 709 | 2 Cone et al. 1993 Plant Cell 5, 1795 | 3 Hollick and Chandler 2001 Genetics 157, 369 | 4 Hale et al. 2007 PLoS Biol. 5, 2156 | 5 Erhard et al. 2009 Science 323, 1201 | 6 Nobuta et al. 2008 PNAS 105, 14958 | 7 Stonaker et al. 2009 PLoS Genet. 5, e1000706 | 8 Barbour et al. 2012 Plant Cell 24, 1761 | 9 Dorweiler et al. 2000 Plant Cell 12, 2101 | 10 Parkinson et al. 2007 Dev. Biol. 308, 462 | 11 Ogas et al. 1999 PNAS 96, 13839 | 12 Carter et al. 2018 Plant Cell 30, 1337 | 13 Ho et al. 2013 Biochim. Biophys. Acta 1829, 199
Keywords: Gene regulation, Development, Chromatin remodeling