Poster abstracts

Poster number 12 submitted by Natalie Deans

The required to maintain repression12 locus provides a novel mechanistic link between paramutation and developmental gene regulation in Zea mays

Natalie Deans (Department of Molecular Genetics, The Ohio State University, Columbus, OH, 43210), Brian Giacopelli (Department of Molecular Genetics, The Ohio State University, Columbus, OH, 43210), Daniel Hlavati, Emily McCormic (Department of Molecular Genetics, The Ohio State University, Columbus, OH, 43210), Charles Addo-Quaye (Department of Biochemistry, Purdue University, West Lafayette, IN, 47907), Brian Dilkes (Department of Biochemistry, Purdue University, West Lafayette, IN, 47907), Jay Hollick (Department of Molecular Genetics, and The Center for RNA Biology, The Ohio State University, Columbus, OH, 43210)

Abstract:

In Zea mays (maize), paramutations facilitate meiotically heritable changes in gene regulation for certain alleles of purple plant1, a gene encoding a transcription factor required for anthocyanin production1. A strongly expressed Pl1-Rhoades allele is suppressed in trans when combined with a transcriptionally and post-transcriptionally repressed Pl1-Rhoades allele, and both alleles are passed on in a repressed (denoted Pl´ ) state. At least sixteen loci whose functions are required to maintain repression (rmr) of Pl´ have been identified in an ethyl methanesulfonate mutagenesis screen. Known RMR proteins that mediate 24 nucleotide (24nt) RNA biogenesis in a pathway presumed to be orthologous to Arabidopsis RNA-directed DNA Methylation (RdDM) pathway which directs repressive chromatin modifications. The fourth protein is unique to 24nt RNA biogenesis in maize. Here we describe four recessive alleles which define the rmr12 locus and complement previously identified rmr factors. Unlike any other rmr-type mutations found to date2, 3, 4, 5, 6, rmr12 mutants display a unique combination of defects, including male gametophyte dysfunction, that indicate a novel mechanistic connection between paramutation and developmental gene control. Whole genome sequence analysis and molecular mapping place rmr12 in an interval on chromosome 9S, and individual rmr12-3 and rmr12-4 mutants have lesions in a gene encoding a chromodomain-helicase-DNA-binding protein 3 (chd3) within this region. CHD3 proteins are chromatin remodelers important for developmental gene regulation in both animals and plants, and defects in human CHD3 proteins have been associated with gastric and colorectal cancers 7, 8, 9, 10. Many poorly understood aspects of CHD3 biology, including its role in directing transgenerational changes in gene regulation, can now be addressed at a specific genomic target.

References:

1. Hollick et al. 1995 Genetics 141, 709. | 2. Dorweiler et al. 2000 Plant Cell 20, 2101. | 3. Parkinson et al. 2007 Dev. Biol. 308, 462. | 4. Hale et al. 2007 PLoS Biol. 5, 2156 | 5. Stonaker et al. 2009 PLoS Genet. 5, e1000706. | 6. Barbour et al. 2012 Plant Cell 24, 1761.| 7. Kehle et al. 1998 Science 282, 1897. | 8. Solari et al. 2000 Curr. Biol. 10, 223. | 9. Ogas et al. 1999 Proc. Natl. Acad. Sci. 96, 13839. | 10. Kim et al. 2011 Histopathology 58, 660.

Keywords: Development, Gene regulation, Chromatin