Nature Genetics34, 450 - 454 (2003)
Published online: 6 July 2003; | doi:10.1038/ng1210
Formation of stable epialleles and their paramutation-like interaction in tetraploid Arabidopsis thaliana
Ortrun Mittelsten Scheid1, Karin Afsar1
& Jerzy Paszkowski1, 2
1
Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH 4058 Basel, Switzerland.
2
Present address: Department of Plant Biology, University of Geneva, 30, Quai Ernest-Ansermet, CH 1211 Geneva 4, Switzerland.
Correspondence should be addressed to Ortrun Mittelsten Scheid ortrun@fmi.ch
Polyploidization is found frequently in plants1,
2, and species previously considered to be diploid may show remnants of earlier polyploidization events on closer inspection of their genomes3. The success of polyploids may lie in increased genetic redundancy supporting subsequent genetic diversification4,
5,
6. 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 formation7,
8,
9,
10,
11,
12,
13. 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.
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