DNA methylation of the wing polyphenism in the pea aphid (Acyrthosiphon pisum)

Phenotypic plasticity is the result of a single genotype producing more than one phenotype in response to different environmental conditions [1].  This phenomenon is now becoming understood in terms of epigenetic inheritance, in which genes can be alternately spliced, silenced, or enhanced by molecular activity that does not affect the original DNA sequence [2].  I am studying DNA methylation in the pea aphid to elucidate the relationship between DNA methylation and the classic wing polyphenism.  Polyphenism is an extreme form of phenotypic plasticity where an identical genome expresses two or more distinct morphs [2].  In the pea aphid there is a trade-off between a reproductive morph that is wingless and a migratory morph that is winged [3].  Previous data has correlated DNA methylation to increased expression levels in the pea aphid and that winged morphs express higher total DNA methylation within their genome.  I hypothesize that differentially methylated genes (DMGs) will have differential expression levels and/or alternative splicing of transcripts that are morph specific.  Utilizing the methylome data of the pea aphid, DMGs and their function will be identified and confirmed with bisulfite conversion and sequencing.  The gene expression levels and alternative splicing will be analyzed by qPCR and PCR.  I will be presenting my research proposal into DNA methylation’s role in the wing polyphenism of the pea aphid, along with the preliminary data.    

References: [1] Pigliucci, Massimo, Courtney Murren, and Carl Schlichting. "Phenotypic plasticity and evolution by genetic assimilation." The Journal of Experimental Biology 209 (2006): 2362-2367. [2] Lyko, F.,  et al.“The Honey Bee Epigenomes: Differential Methylation of the Brain DNA in Queens and Workers.” PLoS Biology. 8 (2010) 1-12.  [2] Lyko, F., et al.“Insects as innocative models for functional studies of DNA methylation.” Trends in Genetics. 27 (2011): 127-131. [3]  Brisson, J. A., “Review: Aphid wing dimorphisms: linking environmental and genetic control of trait variation” Phil. Trans. R. Soc. B. 365 (2010): 605-616.