Title

Genome-­wide demethylation affects epigenetic inheritance of a defensive trait in Mimulus guttatus

Presenter Information

Amanda Stout
Alison Scoville

Document Type

Oral Presentation

Location

SURC 135

Start Date

17-5-2012

End Date

17-5-2012

Abstract

Damage to leaves of Mimulus guttatus (yellow monkyflower) results in increased density of trichomes, which are hair-like structures that can help defend against insect herbivores. Damage can also result in alteration of flowering time. Remarkably, these phenotypic changes are inherited by offspring even though they do not involve a change in DNA sequence. This phenomenon is known as epigenetic inheritance. In other organisms, epigenetic inheritance is associated with heritable patterns of methylation in the promotor region of particular genes. Here I investigated whether methylation is involved in epigenetic inheritance of damage-induced phenotypes in two recombinant inbred lines of M. guttatus. For each line, I grew seeds derived from multiple damaged and undamaged parents, both with and without treatment with the genome-wide demethylating agent 5-azacytidine. I measured trichome density and flowering time for all progeny. In line 94, genome-wide demethylation erased differences in trichome density between the progeny of damaged and undamaged plants, as expected. However, in line 85, genome-wide demethylation reversed the effect of parental damage on trichome density. In both lines, genome-wide demethylation exposed otherwise unexpressed differences in flowering time between the progeny of damaged and undamaged plants. My results suggest that mechanisms other than methylation are involved in epigenetic inheritance of these traits, and that methylation can mask as well as create inherited differences in the progeny of damaged vs. undamaged plants. Further investigation of this system will lead to increased understanding of the complex mechanisms, ecological significance, and evolution of epigenetic inheritance of environmentally induced traits.

Faculty Mentor(s)

Alison Scoville

Additional Mentoring Department

Biological Sciences

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Genome-­wide demethylation affects epigenetic inheritance of a defensive trait in Mimulus guttatus

SURC 135

Damage to leaves of Mimulus guttatus (yellow monkyflower) results in increased density of trichomes, which are hair-like structures that can help defend against insect herbivores. Damage can also result in alteration of flowering time. Remarkably, these phenotypic changes are inherited by offspring even though they do not involve a change in DNA sequence. This phenomenon is known as epigenetic inheritance. In other organisms, epigenetic inheritance is associated with heritable patterns of methylation in the promotor region of particular genes. Here I investigated whether methylation is involved in epigenetic inheritance of damage-induced phenotypes in two recombinant inbred lines of M. guttatus. For each line, I grew seeds derived from multiple damaged and undamaged parents, both with and without treatment with the genome-wide demethylating agent 5-azacytidine. I measured trichome density and flowering time for all progeny. In line 94, genome-wide demethylation erased differences in trichome density between the progeny of damaged and undamaged plants, as expected. However, in line 85, genome-wide demethylation reversed the effect of parental damage on trichome density. In both lines, genome-wide demethylation exposed otherwise unexpressed differences in flowering time between the progeny of damaged and undamaged plants. My results suggest that mechanisms other than methylation are involved in epigenetic inheritance of these traits, and that methylation can mask as well as create inherited differences in the progeny of damaged vs. undamaged plants. Further investigation of this system will lead to increased understanding of the complex mechanisms, ecological significance, and evolution of epigenetic inheritance of environmentally induced traits.