Table6_Transcriptome analysis of megalurothrips usitatus (Bagnall) identifies olfactory genes with ligands binding characteristics of MusiOBP1 and MusiCSP1.docx

The olfactory system is an important component of insect behavior and is vital for survival and reproduction. However, the genomic characterization and molecular basis of the olfactory response of Megalurothrips usitatus remain relatively unknown. RNA sequencing-built developmental transcriptomes of nymphs, pupae, and adult M. usitatus were examined in order to establish the sequence-based background of M. usitatus olfactory responses. A total of 56,669 unigenes were annotated using GO, NR, Pfam, eggNOG, SwissProt, and KEGG. The number of differentially expressed genes between pupae and nymphs, males and nymphs, and females and nymphs were 10,498, 9,235, and 10,964, respectively. One odorant-binding protein (MusiOBP1) and one chemosensory protein (MusiCSP1) were selected from the transcriptome, and their full-length sequences were obtained using RACE PCR. The relative expression of MusiOBP1 was the highest in primordial females, whereas the relative expression of MusiCSP1 was the highest in primordial pupae. The strongest binding ability to the odor-binding protein MusiOBP1 was observed for β-citronellol. 3-Hydroxy-2-methyl-4-pyrone showed the strongest binding affinity to MusiCSP1. Our analysis suggests that MusiOBP1 and MusiCSP1 may play significant roles in mediating M. usitatus host recognition. This research will improve our knowledge of odorant-binding proteins and chemosensory proteins, which will in turn improve our understanding of insect olfactory systems.

嗅觉系统是昆虫行为的核心组成部分，对昆虫的生存与繁衍具有关键意义。然而，亮蓟马（Megalurothrips usitatus）嗅觉响应的基因组特征及分子基础目前仍有待深入解析。本研究针对通过RNA测序构建的亮蓟马若虫、蛹与成虫发育转录组开展系统性分析，旨在建立该物种嗅觉响应的序列基础。共计56669条单基因（unigene）通过基因本体（Gene Ontology, GO）、非冗余蛋白序列数据库（Non-Redundant Protein Sequence Database, NR）、蛋白质家族数据库（Pfam）、进化基因类群数据库（eggNOG）、瑞士蛋白数据库（SwissProt）及京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）完成功能注释。蛹与若虫、雄虫与若虫、雌虫与若虫之间的差异表达基因数量分别为10498、9235和10964个。本研究从转录组中筛选得到1个气味结合蛋白（odorant-binding protein, OBP）及1个化学感受蛋白（chemosensory protein, CSP），分别命名为MusiOBP1与MusiCSP1，并通过快速扩增cDNA末端聚合酶链式反应（RACE PCR）获得二者的全长编码序列。MusiOBP1在初生雌成虫中的相对表达量最高，而MusiCSP1在初生蛹中的相对表达量最高。β-香茅醇（β-citronellol）与MusiOBP1的结合活性最强。3-羟基-2-甲基-4-吡喃酮（3-Hydroxy-2-methyl-4-pyrone）与MusiCSP1的结合亲和力最高。本研究分析表明，MusiOBP1与MusiCSP1可能在介导亮蓟马寄主识别的过程中发挥关键作用。本研究将深化学界对气味结合蛋白与化学感受蛋白的认知，进而推动对昆虫嗅觉系统的深入理解。