Proteomics Research On The Wing Dimorphism Of Aphids

Aphids are one of the main pests of alfalfa.They reduce the yield and nutritional value of the host plant by feeding on their phloem tissue and transmitting many viruses.The damages of aphids are closely related to its wing polymorphism.However,studies on wing dimorphism of aphids are still little,especially on molecular levels.Studies on the wing dimorphism of aphids not only reveal the molecular mechanisms of this phenomenon,but provide assistance for the study of wing dimorphism of other insects.In this study,isobaric tags for relative and absolute quantitation(iTRAQ)were used to investigate the differential proteomics profiling between alate and apterous morphs of pea aphids Acyrthosiphon pisum at fourth instar-nymph and adult stage,respectively.Based on the analysis,the transcriptional expression of differentially expressed proteins(DEPs)that involved in chemical sensing was performedby quantitative real-time PCR(qRT-PCR).(1)A total of 846 DEPs were detected and 569 and 500 DEPs were found at the 4th instar-nymph and adult stages,respectively.There were 170 DEPs that were commonly up-regulated in alate morphs at two developmental stages while 44 commonly down-regulated.KEGG enrichment analysis revealed that DEPs were significantly enriched in the energy metabolism and amino acid biosynthesis and metabolic pathways.DEPs were significantly enriched in the PPAR signaling pathway.(2)In addition,29 differentially expressed proteins detected by iTRAQ verified by quantitative real-time PCR(qRT-PCR).(3)The transcriptional expression profiles of DEPs that involved in chemosensory of aphids including odorant-binding proteins(OBPs)and chemosensory proteins(CSPs)were examined by qRT-PCR at different developmental stages and tissues of winged and wingless morphs.The results showed that the expression levels of OBPs and CSPs were significant difference.Two OBPs(OBP6 and OBP10)and one CSP(CSPORF2)were uniquely or primarily expressed in antennae compared with other tissues and higher expression in alate morphs,indicating an important olfactory role of these genes for alates.The other two CSPs(CSPORF1 and CSPORF5)which were abundant in alates were specifically expressed on legs and wings.One CSP(CSP1L)was mainly expressed in the abdomen,and its expression was significantly higher in apterous morphs,suggesting that it may be involved in the development and reproduction.(4)The types sensilla and the ultrastructure of main olfactory sensilla including placoid sensillum and stellate sensillum on the antennae of Therioaphis persicae were observed with scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Based on the reseach,immunolocalization of OBP6 and the other 40BPs was performed.The results suggested that among the five antibodies,OBP6 and OBP8 were specificity in placoid sensillum as well as specifically labeled on the stellate sensillum,suggesting that OBP6 and OBP8 have the function of chemoreception and perceive the alarm pheromone-germacrene A.