title: Ecdysone signaling underlies the pea aphid transgenerational wing polyphenism.
abstract: The wing polyphenism of pea aphids is a compelling laboratory model with which to study the molecular mechanisms underlying phenotypic plasticity. In this polyphenism, environmental stressors such as high aphid density cause asexual, viviparous adult female aphids to alter the developmental fate of their embryos from wingless to winged morphs. This polyphenism is transgenerational, in that the pea aphid mother experiences the environmental signals, but it is her offspring that are affected. Previous research suggested that the steroid hormone ecdysone may play a role in this polyphenism. Here, we analyzed ecdysone-related gene expression patterns and found that they were consistent with a down-regulation of the ecdysone pathway being involved in the production of winged offspring. We therefore predicted that reduced ecdysone signaling would result in more winged offspring. Experimental injections of ecdysone or its analog resulted in a decreased production of winged offspring. Conversely, interfering with ecdysone signaling using an ecdysone receptor antagonist or knocking down the ecdysone receptor gene with RNAi resulted in an increased production of winged offspring. Our results are therefore consistent with the idea that ecdysone plays a causative role in the regulation of the proportion of winged offspring produced in response to crowding in this polyphenism. Our results also show that an environmentally regulated maternal hormone can mediate phenotype production in the next generation, as well as provide significant insight into the molecular mechanisms underlying the functioning of transgenerational phenotypic plasticity.
authors.affiliation: School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588.
authors.forename: Neetha Nanoth
authors.initials: NN
authors.lastname: Vellichirammal
authors.affiliation: Department of Biology, University of Rochester, Rochester, NY 14627.
authors.forename: Purba
authors.initials: P
authors.lastname: Gupta
authors.affiliation: Department of Life Sciences, University of the West Indies, Mona, Kingston 7, Jamaica.
authors.forename: Tannice A
authors.initials: TA
authors.lastname: Hall
authors.affiliation: Department of Biology, University of Rochester, Rochester, NY 14627; jennifer.brisson@rochester.edu.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Brisson
mesh_terms: D000818:Animals; D001042:Aphids / Q000187:drug effects* / Q000196:embryology / Q000235:genetics; D003441:Crowding; D004440:Ecdysone / Q000378:metabolism / Q000494:pharmacology*; D004441:Ecdysterone / Q000494:pharmacology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D009024:Morphogenesis / Q000187:drug effects* / Q000235:genetics; D018532:Pisum sativum / Q000469:parasitology; D010641:Phenotype; D034622:RNA Interference; D011987:Receptors, Steroid / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014315:Triterpenes / Q000494:pharmacology; D014921:Wings, Animal / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism
chemical_list: D019476:Insect Proteins; D011987:Receptors, Steroid; D014315:Triterpenes; C055469:ecdysone receptor; C041246:cucurbitacin B; D004440:Ecdysone; D004441:Ecdysterone
keywords: Acyrthosiphon pisum; ecdysone signaling; pea aphid; phenotypic plasticity; wing polyphenism