title: Formation of stable epialleles and their paramutation-like interaction in tetraploid Arabidopsis thaliana.
abstract: Polyploidization is found frequently in plants, and species previously considered to be diploid may show remnants of earlier polyploidization events on closer inspection of their genomes. The success of polyploids may lie in increased genetic redundancy supporting subsequent genetic diversification. Although doubling the genome does not generate diversity per se, recent studies show that rapid genomic rearrangements and changes in DNA modification and gene expression patterns are associated with polyploid formation. But recessive modifications will not become phenotypically apparent in early polyploid generations. Here we show that epialleles in tetraploid plants (but not in diploids) interact in trans and lead to heritable gene silencing persisting after segregation from the inactivating allele. This mechanism, resembling paramutation, leads to the establishment of functional epigenetic homozygosity and, thus, to conversion of new recessive alleles into traits expressed in early polyploid generations. Such interactions probably contribute to rapid adaptation and evolution of polyploid plant species.
authors.affiliation: Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH 4058 Basel, Switzerland. ortrun@fmi.ch
authors.forename: Ortrun
authors.initials: O
authors.lastname: Mittelsten Scheid
authors.forename: Karin
authors.initials: K
authors.lastname: Afsar
authors.forename: Jerzy
authors.initials: J
authors.lastname: Paszkowski
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D005075:Biological Evolution; D002934:Cinnamates; D003433:Crosses, Genetic; D019175:DNA Methylation; D004171:Diploidy; D004351:Drug Resistance / Q000235:genetics; D017343:Genes, Plant; D006921:Hygromycin B / Q000031:analogs & derivatives* / Q000494:pharmacology; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D011123:Polyploidy
chemical_list: D002934:Cinnamates; D006921:Hygromycin B; C026273:hygromycin A; D017853:Phosphotransferases (Alcohol Group Acceptor); C063242:hygromycin-B kinase