Integrative Genomic Approaches to Studying Epigenetic Mechanisms of Phenotypic Plasticity in the Aphid

Phenotypic plasticity is the nongenic variation in phenotype due to environmental factors. It is a common phenomenon in the animal kingdom that is not well understood at the molecular level. A tenable form of phenotypic plasticity for molecular research is polyphenism, which is an extreme form of phenotypic plasticity that results in discrete, alternative morphs. Epigenetic mechanisms have been hypothesized as the molecular regulators of polyphenism, in particular DNA methylation and chromatin remodeling. The pea aphid exhibits multiple polyphenisms including winged and wingless females during summer (wing polyphenism) and asexual and sexual morphs during summer and fall, respectively (reproductive polyphenism). The aphid is ideally situated for research into the molecular basis of polyphenism, with a sequenced genome and multiple transcriptomic studies that have begun identifying key molecular regulators of these two polyphenisms. The aphid also possesses the genes necessary for DNA methylation and chromatin remodeling. The pea aphid system is thus primed for future research into the epigenetic regulation of polyphenisms.