关键词: 花椒窄吉丁, 触角转录组, 基因注释, 气味结合蛋白, 化学感受蛋白

Abstract: 【Aim】 To establish the antennal transcriptome database of Agrilus zanthoxylumi adult and to explore target genes related to olfaction, so as to provide the theoretical basis for the future study of the chemosensory mechanism of its antenna and its biological control. 【Methods】 High-throughput sequencing platform Illumina NovaSeq 6000 was used for transcriptome sequencing of the antennae of female and male adults of A. zanthoxylumi. Trinity software was used for sequence splicing and assembly of the high-quality reads obtained. BLAST software was used to compare the antennal transcriptome data with public databases NR, NT, Swiss-Prot, GO, KEGG, BLASTX, eggNOG, Pfam, TmHMM, SignalP, KO, Map, BLASTP and RNAMMER. Phylogenetic analysis was carried out using MEGA software based on the nucleotide sequences of the preliminarily screened candidate odorant binding proteins (OBPs) and chemosensory proteins (CSPs) of A.zanthoxylumi, and homologous proteins from other coleopteran insects. The RPKM (reads per kilobase per million mapped reads) value was used to evaluate the expression levels of olfaction-related genes. 【Results】 By sequencing of the antennal transcriptome of female and male adults of A. zanthoxylumi, a total of 36 209 unigenes and 90 982 transcripts were obtained with the N50 of 2 103 and 2 523 bp, respectively, indicating the high completeness of assembly. Most unigenes (41.62%) were annotated to the NR database, with the highest proportion (19%) of genes similar to those of Tribolium castaneum. In the GO database, 11 614 unigenes were annotated and divided into 57 branches of three functional categories, cellular component, molecular function and biological process, among which binding (70.57%) and catalytic activity (45.51%) related unigenes in the category of molecular function were the most. The KEGG metabolic pathway analysis indicated that 7 427 unigenes are involved in five categories of metabolic pathways, with the most unigenes (815) involved in signal transduction. Seven candidate OBP genes and 5 CSP genes with full-length open reading frame were screened, and their encoded proteins have the typical characteristics of chemosensory protein family. The phylogenetic analysis showed that the OBPs and CSPs of A. zanthoxylumi have the highest sequence identity with the OBPs and CSPs of A. mali, respectively. The RPKM values showed that AzanOBP1 and AzanOBP2 were not expressed in the antennae of female adults, but slightly expressed in the antennae of male adults, and AzanOBP3 was expressed with high abundance in the antennae of male adults. 【Conclusion】 For the first time, the antennal transcriptome data of A. zanthoxylumi were obtained, and the olfaction-related OBP, CSP, OR, IR and SNMP genes of A. zanthoxylumi were screened. It is speculated that OBPs expressed with high abundance in the antennae play a key role in identifying pheromones released by female adults of the same species or the volatiles released by host plants. The results can lay a molecular basis for further studying the functions of chemosensory genes and olfactory sensitivity mechanism of A. zanthoxylumi.

Key words: Agrilus zanthoxylumi, antennal transcriptome, gene annotation, odorant binding protein, chemosensory protein