| Sitobion avenae(Fabricius)is a major pest in wheat field throughout the world. They damage gramineous crops by sucking phloemsap as well as transmitting plant viruses. The plant growth will become slower and the tiller will be reduced after attacked by them. The yield and quality of wheat were severely affected by them. At present, chemical control is mainly used and the use of pesticides and pesticide residues is not only harmful to people and animals, but also caused serious environmental pollution. Therefore, the research and application of green prevention and control technology widely used seem extremely important. The “push-pull strategy” using the volatiles of plant or aphid alarm pheromone to repel aphids and attract natural enemies has been the research hotspot.Insect antennae are the main organs for perceiving volatile. Research on insect antennal sensilla especially on chemical sensilla is the physiological basis of insect chemical ecology. And working on olfactory related proteins in the process of olfactory recognition is good to understand the physiological mechanism of the perception of the volatile, like odorant binding proteins(OBPs) and chemosensory proteins(CSPs). Because there is no systematic study on antennal sensilla and olfactory related proteins in S. avenae, in this paper, the ultrastructural of antennae of S. avenae was observed using scanning electron microscopy and 3D digital microscope; Odorant-binding proteins(OBPs) and chemosensory proteins(CSPs) were identified, which are important in the process of odor substances recognition, by antennal transcriptome of winged and wingless S. avenae. Then we analyzed their expression profiles in different tissues and ages by quantitative real-time PCR. The expected results of project have a significant value on knowing.The type, number, distribution and ultra morphology of antennal sensilla of both winged and wingless adults of S. avenae were observed and compared using scanning electron microscopy and 3D digital microscope, to analyze the differences of antennal sensilla and enrich the morphological theory of S. avenae. The results showed that there are mainly 5 types of antennal sensilla, such as the primary rhinaria, secondary rhinaria, trichoid sensillum, coeloconic pegs and campaniform sensillum. And the primary rhinaria is an aggregate structure of 1 large placoid sensillum, 2 smaller placoid sensillum and 4 coeloconic pegs. The analysis results revealed that all types of sensilla have their stable distribution pattern among different aphids either with or without wing, but there are differences on their quantities and sizes. At the same time, antennae of each age were also observed; the results indicated 1st and 2nd instar aphid antennae only have 5 segments until the third instar began to appear constricted on the third changing into six sections. In addition, there was no difference in the kinds of proprioceptors. There were no secondary rhinarias and peripheral scolopidia on nymphs? antennae.A total of 147,665 distinct transcripts(mean length = 652 bp) and 133,331 unigenes(mean length = 594 bp) obtained from the S. avenae winged and wingless antennae libraries by Illumiuna RNA-seq platform. Then the transcripts were annotated by seven databases(Nr, Nt, Pfam, KOG/COG, Swiss-prot, KEGG and GO databases). 13 OBP and 5 CSP genes were identified from S. avenae, among which 6 OBPs and 3 CSPs were first discovered. All of them had the characteristic insect sequence motif and we found a Plus-C OBP( Save OBP5). A total of 161 OBP protein sequences from 21 different Hemiptera insects 50 CSPs from 7 different Hemiptera insects were used for the phylogenetic analysis. Most orthologous sequences in the S. avenae OBPs were largely limited to aphid OBPs with a high bootstrap value and 4 of them showed high homology with A. pisum.We examined the differential expression of these olfactory genes in different ages(1st instar nymph, 2nd instar nymph, 3rd winged instar nymph, 3rd wingless instar nymph, 4th winged instar nymph, 4th wingless instar nymph, winged and wingless adults) and tissues of winged and wingless aphids(antennae, heads without antennae, winged thoraxes, wingless thoraxes, winged abdomens and legs). The expression levels of SaveOBPs and SaveCSPs were affected by age. Seven OBPs(SaveOBP6, SaveOBP7, SaveOBP9, SaveOBP10, SaveOBP13, SaveOBP14 and SaveOBP15) and one CSP(SaveCSP1) were uniquely or primarily expressed in antennae compared with other tissues, indicating a vital olfactory role for these genes. Apart from antenna, some of transcripts were abundant expressed in other tissues of winged or wingless aphid. SaveOBP8, SaveCSP2 and SaveCSP5 were highly expressed in legs of winged or wingless aphids; SaveOBP2 were mainly expressed in heads of winged and wingless aphids; The expressions of SaveOBP1 in heads, thoraxes and abdomens of winged and wingless aphids were higher than in antenna and legs of winged and wingless aphids; SaveOBP3, SaveOBP4, SaveCSP3 and SaveCSP4 were expressed in all tissues of winged and wingless aphids. SaveOBPs and SaveCSPs have very complex expression profiles, both relative to body tissues and developmental stages, presumably in connection with their different roles in aphid behaviors Our findings provided genes for further functional studies of olfactory system of S. avenae at the molecular level and their potential as novel targets for pest control. |
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