Abstract
Wing dimorphism is a widespread phenomenon in insects with an associated trade-off between flight capability and fecundity. Despite the molecular underpinnings of phenotypic plasticity that has already been elucidated, it is still not fully understood. In this study, we focused on the differential proteomics profiles between alate and apterous morphs of the pea aphid, Acyrthosiphon pisum at the fourth instar nymph and adult stages, using isobaric tags for relative and absolute quantitation (iTRAQ) in a proteomic-based approach. A total of 5,116 protein groups were identified and quantified in the three biological replicates, of which 836 were differentially expressed between alate and apterous morphs. A bioinformatics analysis of differentially expressed protein groups (DEPGs) was performed based on gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). KEGG enrichment analysis showed that DEPGs mainly participated in energy metabolism, amino acid biosynthesis and metabolism, and signal sensing and transduction. To verify the reliability of proteomics data, the transcriptional expression of 29 candidates of differentially expressed proteins were analyzed by quantitative real-time PCR (qRT-PCR), showing that 26 genes were consistent with those at proteomic levels. In addition, differentially expressed proteins between winged and wingless morphs that were linked to olfactory sense were investigated. Quantitative real-time PCR revealed the tissue- and morph-biased expression profiles. These results suggested that olfactory sense plays a key role in wing dimorphism of aphids. The comparative proteomic analysis between alate and apterous morphs of the pea aphid provides a novel insight into wing development and dimorphism in aphids and will help facilitate our understanding of these concepts at molecular levels.
Highlights
Phenotypic plasticity is a life history strategy of organisms, allowing them to adapt to various environmental conditions (Hall, 1999; West-Eberhard, 2003)
Based on 4-plex isobaric tags for relative and absolute quantitation (iTRAQ) proteomic labeling and LC-MS/MS analysis, a total of 5,116 protein groups were identified quantified in all experiments at the two developmental stages and three replicates (Table S2)
A total of 538 differentially expressed protein groups (DEPGs) were up-regulated under at least one developmental stage, including 168 DEPGs upregulated at two stages (N4W/N4WL and AW/AWL), and 200 and 168 DEPGs up-regulated at N4W/N4WL and AW/AWL, respectively
Summary
Phenotypic plasticity is a life history strategy of organisms, allowing them to adapt to various environmental conditions (Hall, 1999; West-Eberhard, 2003). With long wings and wing musculature, are capable of longdistance flight and migration to new habitats with fresh resources from deteriorated environments (Harrison, 1980; Roff, 1990), whereas short-wing or wingless morphs, without flight muscles, produce offsprings earlier and have greater reproductive output relative to dispersal morphs (Harrison, 1980; Zera et al, 1997; Simpson et al, 2011). Wing dimorphism has been studied across a wide range of wing-polymorphic insect species, such as short-/long-winged morphs in crickets (Zhao and Zera, 2002), migratory locusts (Simpson and Sword, 2009; Tanaka and Nishide, 2012), and planthoppers (Denno et al, 1989; Xue et al, 2010), as well as wingless (apterous)/winged (alate) morphs in aphids (Brisson et al, 2007; Xu et al, 2011; Yang et al, 2014; Shang et al, 2016; Vellichirammal et al, 2016)
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