Transcriptome Analysis and Molecular Characterization of Olfactory
Binding Protein genes in Parasitoid wasp Anagrus
nilaparvatae(Hymenoptera: Mymaridae)
Abstract
Anagrus nilaparvatae is an important egg parasitoid wasps of rice pests
rice planthopper. Based on the powerful olfactory system of sensing
chemical information in nature, A. nilaparvatae shows complicated life
activities and behaviors, such as feeding, mating and hosting. In this
study, we constructed a full-length transcriptome library and further to
identify the characteristics of olfactory binding proteins, the first
participant in the olfactory system. Through full-length transcriptome
sequencing, splicing, assembly, and data correction by Illumina, we
obtained 163.59Mb of transcriptome data and 501,179 items of annotation
information, and performed GO functional classification of unigenes of
the transcriptome. We analyzed the sequence characteristics of olfactory
binding protein genes, and 8 genes (AnilOBP2, AnilOBP9 AnilOBP23,
AnilOBP56, AnilOBP83, AnilCSP5, AnilCSP6 and AnilNPC2) were identified.
After sequence alignment and conserved domain prediction, the 8 proteins
were consistent with the typical characteristics of OBPs, CSPs and NPC2s
in insects. The phylogenetic tree analysis showed that the 8 genes share
low homology relationship with other species in Hymenopteran. Finally,
RT-qPCR was used to analyze the expression responses of the 8 genes in
different genders and stimulated by volatiles. The relative expression
levels of AnilOBP9, AnilOBP26, AnilOBP83, AnilCSP5 and AnilNPC2 in males
were significantly higher than those in female, while the relative
expression levels of AnilCSP6 were opposite. The expression levels of
AnilOBP9 and AnilCSP6 were significantly altered by the stimulation of
β-caryophylene, suggesting the two genes may be related to host
searching. In this study, the transcriptome data of parasitoid wasps A.
nilaparvatae could provide a reference for the molecular biology
research of the parasitoids, and the identification and analysis of
olfactory binding proteins not only help us further clarify the
physiological characteristics and parasitic mechanism of the
parasitoids, but also promote the utilization of natural enemy
resources.