title: Screening of target genes for RNAi in Tetranychus urticae and RNAi toxicity enhancement by chimeric genes.
abstract: Due to its rapid development of resistance to nearly all arrays of acaricide, Tetranychus urticae is extremely hard to control using conventional acaricides. As an alternative control measure of acaricide-resistant mites, RNA interference (RNAi)-based method has recently been suggested. A double-stranded RNA (dsRNA) delivery method using multi-unit chambers was established and employed to screen the RNAi toxicity of 42 T. urticae genes. Among them, the dsRNA treatment of coatomer I (COPI) genes, such as coatomer subunit epsilon (COPE) and beta 2 (COPB2), resulted in high mortality [median lethal time (LT50)=89.7 and 120.3h, respectively]. The transcript level of the COPE gene was significantly (F3,9=16.2, P=0.001) reduced by up to 24% following dsRNA treatment, suggesting that the toxicity was likely mediated by the RNAi of the target gene. As a toxicity enhancement strategy, the recombinant dsRNA was generated by reciprocally recombining half-divided fragments of COPE and COPB2. The two recombinant dsRNAs exhibited higher toxicity than the respective single dsRNA treatments as determined by LT50 values (79.2 and 81.5h, respectively). This finding indicates that the recombination of different genes can enhance RNAi toxicity and be utilized to generate synthetic dsRNA with improved RNAi efficacy.
authors.affiliation: Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Deok Ho
authors.initials: DH
authors.lastname: Kwon
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Patil Anandrao
authors.initials: PA
authors.lastname: Ashok
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Unggyu
authors.initials: U
authors.lastname: Lee
authors.affiliation: Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea; Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea. Electronic address: shlee22@snu.ac.kr.
authors.forename: Si Hyeock
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D055785:Gene Knockdown Techniques / Q000379:methods; D018390:Gene Targeting / Q000379:methods; D005796:Genes / Q000235:genetics; D005820:Genetic Testing / Q000379:methods; D010571:Pest Control / Q000379:methods; D034622:RNA Interference; D040102:Tetranychidae / Q000187:drug effects / Q000235:genetics*
keywords: COPI coatomer; Lethal dsRNA; RNA interference; Tetranychus urticae; Toxicity enhancement