Frankliniella occidentalis is a notorious polyphagous crop pest causing tremendous economic loss. It damages flowers and leaves of host plants and also carries severe plant viruses. During last few decades, it has spread to all continents via transport of plant materials. Following extensive use of insecticides to control F. occidentalis, it has developed high level of resistance due to its short life cycle and high reproductive potential. In this study, RNA interference (RNAi)-based bioassay system was developed to find an alternative control measure for insecticide-resistant population of F. occidentalis. A variety of genes involved in various physiological mechanisms were selected for the test of dsRNA potency (tubulin, v-ATPase, amylase, aquaporin etc.). Each bioassay unit made by 3D printing has a leaf disc placed on 150 ㎕ of 50 ng/ul dsRNA solution and 20 thrips. The mortality was checked, and the dsRNA and leaf disc were replaced every 24 h for 72 h. Of the 20 genes tesetd, tubulin, v-ATPase, and aquaporin showed 31, 38, 38 and 45% of corrected mortality at 72 h post-treatment, respectively. This result suggests the potential of these genes as candidate lethal genes for RNAi-based F. occidentalis control system.

담배가루이(Bemisia tabaci)의 약제에 대한 저항성 문제를 해결하기 위한 방편 의 일환으로 RNA interference(RNAi)를 이용한 해충방제가 시도되고 있다. 본 연 구에서는 RNAi를 이용하여 담배가루이 방제를 위한 target 유전자들을 선발하기 위해 gateway system을 이용한 담배가루이 cDNA library 제작하고, RNAi에 적절 한 약 100-400bp의 insert를 확인하였다. 또한, blast search 및 EST database 비교 분석 결과, 대부분이 담배가루이 관련 유전자임을 확인하였고, 최종적으로 1.75⨉ 106 titer의 담배가루이 cDNA library를 완성하였다. 완성한 cDNA library를 att site 를 가지는 TRV(tobacco rattle virus) RNA2 vector에 LR recombination한 다음 Agrobacterium tumefaciens (EHA105)에 transformation 후 sequencing을 통해 redundancy를 확인하였다. A. tumefaciens (EHA105)에 transformation된 cell을 토 마토에 Agro-infiltration 시킨 후 담배가루이가 섭식하여 체내에서도 RNAi의 발현 을 유도하면 담배가루이 살충 또는 기피효과를 행동학적 변화로 확인하고, 또한 이 와 관련된 target 유전자를 선발하는데 이용될 수 있을 것으로 사료된다.

In this study, to further understand the mechanism of animal growth and to develop a miniature transgenic animal model, we constructed and tested tetracycline-inducible RNAi system using shRNA targeting the mRNA of mouse insulin-like growth factor (mIGF-1) or mouse growth hormone receptor (mGHR) gene. Quantitative real-time PCR analysis of mouse liver cell (Hepa1c1c7) cells transfected with these vectors showed 85% or 90% of expression inhi-bition effect of IGF-1 or GHR, respectively. In ELISA analysis, the protein level of IGF-1 in the cells expressing the shRNA targeting IGF-1 mRNA was reduced to 26% of non-transformed control cells. Unexpectedly, in case of using shRNA targeting GHR, the IGF-1 protein level was decreased to 75% of control cells. Further experiments are needed to explain the lower interference effect of GHR shRNA in IGF-1 protein. Accumulated knowledge of this approach could be applicable to a variety of related biological area including gene function study, gene therapy, development of miniature animals, etc.