关键词: 朱砂叶螨, β-N-乙酰己糖胺酶, 20羟基蜕皮酮, 差异表达基因, RANi

Abstract: 【Aim】 The aim of this study is to analyze the function of β-N-acetylhexosaminase gene TecHEX3 of Tetranychus cinnabarinus during molting, which is the key enzyme gene in the chitin degradation pathway, so as to lay the foundation for the development of a new safe biopesticide against T. cinnabarinus. 【Methods】TecHEX3 from T. cinnabarinus was cloned using PCR and analyzed using bioinformatics methods. The expression levels of TecHEX3 in different developmental stages (egg, larva, nymph and adult), and nymphs fed with 20-hydroxyecdysone (20E) were assayed using RT-qPCR. The efficiency of silencing TecHEX3 of female adult and nymph of T. cinnabarinus through RNAi was analyzed using the feeding method, and the mortality and lethal phenotype of nymphs were counted and observed. 【Results】 TecHEX3 (GenBank accession number: OR413561) was cloned from T. cinnabarinus and the encoded protein belongs to the 20-glycoside hydrolase family. Phylogenetic tree indicated its closest relationship to TuHEX3 of T. urticae, placing it in beta-N-acetylhexosaminase group IV. TecHEX3 was expressed in various developmental stages of T. cinnabarinus, with the highest expression level observed in adults. The best induction of TecHEX3 expression was achieved by feeding 500 ng/μL of 20E. RNAi results demonstrated that the expression level of TecHEX3 in T. cinnabarinus nymphs fed with dsTecHEX3 was significantly reduced by 81% as compared to that of the control group (fed with dsEGFP). Silencing TecHEX3 resulted in failure to shed the old cuticle or abnormal morphology of T. cinnabarinus, causing a mortality rate of 40.58%. 【Conclusion】 TecHEX3 plays an important role in the molting development of T. cinnabarinus by involvement in the chitin degradation process.

Key words: Tetranychus cinnabarinus, beta-N-acetylhexosaminase, 20-hydroxyecdysone, differentially expressed gene, RNAi