Identification And Expression Profile Analysis Of Odorant-binding Proteins Genes Based On Transcriptome In Grasshopper, Oedaleus Asiaticus

Olfaction plays an important role in many life activities of insect, such as feeding, host finding, avoid predators, mating and spawning. In their olfaction systems, odorant-bikiding proteins (OBPs) are believed to be a key component. Here, we for the first time identified 15 OBPs, OBP1-15, of a grasshopper. Oedaleus asiaticus using the next-generatior, sequencing method. Then, we determined the expression profile of these 15 OBP gene; and made a phylogenetic analysis between the OBPs of Oedaleus asiaticus and 6 other species of insects. The main results are as follows:1. Identification of the OBP genes from the antennae of male and female adults of Oedaleus asiaticus by RNA-seq.From the results of sequencing, we acquired 137,426,706 and 127,822,838 total clean reads from female and male, respectively. And the number of the total clean nucleotides are both exceed 10 GB,12.368,403,540 nt and 11,504,055,420 nt from female and male. De novo assembly was performed with the short reads assembling software, then we acquired 6,1629 all-unigene and 2,6064 (42.3%) were annotated. For the first time, we identified 15 OBP genes from the transcriptome database, and all of them had the full-length ORF (open reading frame).2. Determining the expression profiles of the 15 OBP genes.Significantly more OBP7 was detected in male than female antennae, but there are 9 OBPs that were more expressed in female than male antennae by quantitative real-time PCR. From the results of the semi-quantitative reverse transcription PCR, OBP9 and OBP 10 are specifically expressed in the antennae; and other OBPs are expressed in the antennae as well as other chemosensory organs, such as the mouthparts and wings.3. Phylogenetic analysis of the OBPs between Oedaleus asiaticus and other insects.Phylogenetic analysis was performed based on the amino acid sequences of 15 OBPs of Oedaleus asiaticus and 6 other species of insects from 6 different orders. The results showed that most of the Oedaleus asiaticus OBPs are similar to those of Locusta migratoria, but some are different. This indicates that the OBPs originally evolved in a common ancestor, but their chemosensory systems are adapted to different ecosystems.