Poster abstracts

Poster number 33 submitted by Ben Oakes

The roles of RNA polymerase IV and the environment in effecting heritable regulatory changes

Benjamin P. Oakes (Molecular, Cellular and Developmental Biology Graduate Program, The Ohio State University, Columbus, Ohio 43210), Jay B. Hollick (Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210; Centers for RNA Biology and Applied Plant Sciences, The Ohio State University, Columbus, Ohio 43210)

Abstract:
Paramutation is a poorly understood behavior in which one parental allele at a given locus induces a meiotically heritable change at the other.1 Such behaviors occur at several maize loci encoding transcriptional activators of flavonoid biosynthesis pathways including red1 (r1), booster1 (b1), purple plant1 (pl1), and pericarp color1 (p1).2 Remarkably, Bernard C. Mikula showed that the extent of heritable changes brought about by paramutations occurring at r1 is influenced by the environment in early development.3 Because RNA polymerase IV (RNAP IV) controls the heritable regulatory status of the Pl1-Rhoades (Pl1-Rh) allele4,5,6 – an allele subject to paramutation – we hypothesize that RNAP IV, and potentially small RNA pathways in general, mediate trans-generational changes influenced by the environment. To test this idea, we applied mutant analysis and similar experimental strategies used by Mikula3 to study environmental effects on pl1 paramutation and genome-wide heritable changes. B73 BC4F2 seedlings segregating for a mutation (rmr6-1) in the gene encoding the RNAP IV largest subunit were grown in a growth chamber during the first two or three weeks of development at varying temperatures and photoperiods. Plants were grown at either 32°C or 22°C and treated with either a 12-hour light/dark cycle (LD) or continuous light (LL)3 and then transplanted to the field. Sibling rmr6-1 and Rmr6-B73 homozygotes identified using a CAPS marker were then backcrossed to B73. Seedling RNA profiles of BC5 progeny from both non-mutant and rmr6-1 mutant fathers that were treated with various conditions during early development (32°C LL, 32°C LD, 22°C LL, and 22°C LD) will be compared to identify environment- and RNAP IV-mediated effects on the genome-wide inheritance of regulatory information. These results will address a potential molecular mechanism effecting trans-generational variation in response to environmental change.

References:
1. Brink Genetics (1956). | 2. Hollick Nat. Rev. Genet. (2017). | 3. Mikula Genetics (1995). | 4. Hollick et al. Genetics (2005). | 5. Erhard et al. Science (2009). | 6. Erhard et al. Plant Cell (2013).

Keywords: Epigenetics, Paramutation, Environment