Epigenetic Control Over Several Quantitative Traits in Strawberry (Fragaria vesca)

Fragaria vesca(2n=14) is an important model Rosaceae species and the completion of its genome sequence heralds the beginning of the post-genomics era for horticultural crops. Gene expression is highly regulated involving multiple transcriptional and post-transcriptional modifications. Additional layers of regulation are encoded by DNA methylation, histone modifications and non-coding RNA molecules, these epigenetic modifications reinforce one another and are not manifested in the primary DNA sequence.  

Alteration in DNA methylation patterns can change the level of gene expression and manifest as changes in phenotypes. However, quantitative variation resulting from changes in epigenetic control largely remains elusive, since it is often masked by allelic variation. Such epigenetic control can be resolved using F.vesca ssp. vesca accession Hawaii 4 that has been sequenced and is now considered a model plant due to its rapid generation time and small genome size. Here we describe the generation of an epi-mutant population by treating seeds of Hawaii-4 with 5-azacytidine, an inhibitor of DNA methylation. We describe the greater level of phenotypic variation observed for quantitative characters such as flowering time, stolon emergence, plant diameter and plant height among these epi-mutant lines. Considerable phenotypic variation was found and epi-mutant lines with early flowering, late flowering, late stolon emergence and dwarfism phenotypes were selected. The DNA methylation status of these lines is being examined using MS-AFLP (methylation sensitive amplified fragment length polymorphism) before performing more detailed analyses on selected lines using whole genome bisulfite sequencing.