Document Type
Article
Publication Date
2007
College/Unit
Davis College of Agriculture, Natural Resources and Design
Department/Program/Center
Division of Plant and Soil Sciences
Abstract
The silencing of one parental set of rRNA genes in a genetic hybrid is an epigenetic phenomenon known as nucleolar dominance. We showed previously that silencing is restricted to the nucleolus organizer regions (NORs), the loci where rRNA genes are tandemly arrayed, and does not spread to or from neighboring protein-coding genes. One hypothesis is that nucleolar dominance is the net result of hundreds of silencing events acting one rRNA gene at a time. A prediction of this hypothesis is that rRNA gene silencing should occur independent of chromosomal location. An alternative hypothesis is that the regulatory unit in nucleolar dominance is the NOR, rather than each individual rRNA gene, in which case NOR localization may be essential for rRNA gene silencing. To test these alternative hypotheses, we examined the fates of rRNA transgenes integrated at ectopic locations. The transgenes were accurately transcribed in all independent transgenic Arabidopsis thaliana lines tested, indicating that NOR localization is not required for rRNA gene expression. Upon crossing the transgenic A. thalianalines as ovule parents with A. lyrata to form F1 hybrids, a new system for the study of nucleolar dominance, the endogenous rRNA genes located within the A. thaliana NORs are silenced. However, rRNA transgenes escaped silencing in multiple independent hybrids. Collectively, our data suggest that rRNA gene activation can occur in a gene-autonomous fashion, independent of chromosomal location, whereas rRNA gene silencing in nucleolar dominance is locus-dependent.
Digital Commons Citation
Lewis, Michelle S.; Pikaard, Diane J.; Nasrallah, Mikhail; Doelling, Jed H.; and Pikaard, Craig S., "Locus-Specific Ribosomal RNA Gene Silencing in Nucleolar Dominance" (2007). Faculty & Staff Scholarship. 2843.
https://researchrepository.wvu.edu/faculty_publications/2843
Source Citation
Lewis MS, Pikaard DJ, Nasrallah M, Doelling JH, Pikaard CS (2007) Locus-Specific Ribosomal RNA Gene Silencing in Nucleolar Dominance. PLoS ONE 2(8): e815. https://doi.org/10.1371/journal.pone.0000815
Comments
© 2007 Lewis et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.