Abstract Detail

Genomics / Proteomics

Xu, Jihua [1], Robinson, Steve [2], Tanino, Karen [1].

Using a hypomethylated population of strawberry to demonstrate that epigenetic variation can be subject to selection.

Epigenetic variation is often associated with phenotypic plasticity. Plasticity suggests an adaptive response and has little value for trait selection. Nevertheless, valuable epigenetic variation can be transmitted, in that differential epigenetic states are inherited in the absence of genetic variation. Epigenetic information is encoded in DNA methylation, post-transcriptional histone modifications, chromatin structure and non-coding RNA molecules that together provide additional levels of regulation of allele expression that affect quantitative traits. However, it remains contentious whether variation in epigenetic marks can be selected and thus questions regarding the evolutionary relevance of such epialleles remain. Here we use strawberry (Fragaria vesca) as a model plant to investigate the potential of DNA methylation patterns to respond to selection. Variation in DNA methylation occurs naturally and although changes to these patterns can be induced by environmental stress, they are often remarkable stable.
To address fundamental questions of the evolutionary relevance of DNA methylation polymorphisms, we generated a hypomethylated population of strawberry plants using a genetically uniform line derived from Hawaii-4, confirmed using AFLP markers. The extent of induced DNA methylation polymorphism in the population was estimated using MS-AFLP markers and an examination of flowering time across individuals from the hypomethylated strawberry population revealed broader variation than that of the wild type control population. The early flowering trait was not only heritable in clonal progeny, but selections made for early flowering variants over three generations revealed that the flowering time phenotype of families derived from early flowering variants could be altered such that they are significantly distinct from wild type. The DNA methylation pattern of these three generations has been analyzed using MS-AFLP where the polymorphisms cluster into families. We have focused on two early flowering lines where gene expression differences will be detected compared to wild type lines using RNA-seq and detailed DNA methylation patterns will be generated using whole genome bisulfite sequencing. Based on these results, we will attempt to identify the epialleles underlying the early flowering trait. This study suggests that epialleles can be subject to selection with evolutionary implications. Although this research demonstrates the inheritance of selected epigenetic variants in strawberry flowering time, strategies utilizing epigenetic variation should be reserved for traits where there is a dearth of genetic polymorphism. Thus epigenetic approaches may generate new resources for breeding and lead to distinctive cultivars with novel phenotypes that are particularly relevant to crops with strict quality restrictions that limit the introduction of exotic germplasm.

1 - University of Saskatchewan, Plant Sciences, 51 Campus Drive, Saskatoon, SK, S7N 5A8, Canada
2 - Agriculture and Agri-food Canada, Saskatoon Research Center, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada

Keywords:
Strawberry
epigenetic
flowering time
DNA methylation
inheritance.

Presentation Type: Oral Paper:Papers for Topics
Session: 48
Location: Salon 19/20/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 3:00 PM
Number: 48007
Abstract ID:1343
Candidate for Awards:2015 Graduate Student Best Oral Presentation Award