Using a Hypomethylated Epi-Mutant Population of Woodland Strawberry to Demonstrate That Flowering Time Can be Subject to Selection

Epigenetic information is encoded in DNA methylation, post-transcriptional histone modifications, chromatin structure and non-coding RNA molecules, which together provide additional levels of regulation of allele expression that affect quantitative traits. To assess the contribution of epialleles (alternative methylation state) on phenotypic variation and determine how these epialleles are inherited, we have developed a novel hypomethylated population of Fragaria vesca (2n=2x=14) using the epimutagen 5-azacytidine from which individuals with altered phenotypes can be identified, selected and characterized.

Analysis using methylation sensitive molecular markers MS-AFLP confirmed alterations in DNA methylation pattern (hypomethylation) induced by 5-azacytidine treatment. An examination of flowering time across individuals from the hypomethylated population revealed extensive variation beyond that of wild-type controls. The early flowering trait tested was not only heritable in clonal progeny, but selections made for early flowering variants over four generations through meiosis revealed the early flowering time phenotype could be maintained. We have focused on two early flowering lines where gene expression differences were detected compared to wild-type lines using RNA-seq and detailed DNA methylation patterns were generated using whole genome bisulfite sequencing. Based on these results, we will attempt to identify the epialleles underlying the early flowering trait. These data will add to the growing evidence that altering epigenetic variation can be a mechanism for generating increased phenotypic diversity and can be subject to selection.