title: Expression of dsRNA in recombinant Isaria fumosorosea strain targets the TLR7 gene in Bemisia tabaci.
abstract: BACKGROUND
  RNA interference (RNAi) technology shows a great potential in controlling agricultural pests, despite the difficulty of introducing exogenous dsRNA/siRNA into target pests. Isaria fumosorosea is a common fungal pathogen of the B-biotype Bemisia tabaci (whitefly), which is a widespread pest. Entomopathogenic fungi directly penetrate the cuticle and invade insect hemocoel. Application of I. fumosorosea expressing dsRNA of whitefly immunity-related gene may aid in developing RNAi technology to effectively control whiteflies.
  
  
  METHODS
  A dsRNA expression plasmid, psTLR7, was constructed by introducing the Toll-like receptor 7 (TLR7) gene of B-biotype whitefly to the silent vector, pSilent-1. The plasmid psTLR7 was transferred into the protoplast of the I. fumosorosea strain IfB01. Then, the recombinant strain was screened out based on the biological stability and bioactivity against whitefly.
  
  
  RESULTS
  A genetically stable recombinant strain IfB01-TRL7 was screened out. The impact of IfB01-TRL7 against whitefly TRL7 gene was validated by qPCR. Lower expression levels of the TLR7 gene was observed in the whiteflies infected by the recombinant strain. The bioassay results indicated that compared to IfB01 strain, IfB01-TRL7 increased the mortality of whitefly nymphs, and decreased and shortened the values of LC50 and LT50, thus indicating higher virulence of IfB01-TRL7.
  
  
  CONCLUSIONS
  The expression of the dsRNA of whitefly TLR7 gene in recombinant I. fumosorosea strain successfully knocked down the host target gene by infecting the nymphs and enhanced the whiteflies mortality. The present study will give insight to new application of RNAi technology for more effective biocontrol of this pests.
authors.affiliation: College of Agriculture, South China Agricultural University, Guangzhou, China. 2409323925@qq.com.
authors.forename: Xiurun
authors.initials: X
authors.lastname: Chen
authors.affiliation: College of Agriculture, South China Agricultural University, Guangzhou, China. 578942719@qq.com.|College of Agronamy, Jiangxi Agricultural University, Nanchang, China. 578942719@qq.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: College of Agriculture, South China Agricultural University, Guangzhou, China. hqbscau@126.com.
authors.forename: Qiongbo
authors.initials: Q
authors.lastname: Hu
authors.affiliation: College of Agriculture, South China Agricultural University, Guangzhou, China. 757510384@qq.com.
authors.forename: Bowen
authors.initials: B
authors.lastname: Zhang
authors.affiliation: College of Agriculture, South China Agricultural University, Guangzhou, China. 1028212450@qq.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.affiliation: College of Agriculture, South China Agricultural University, Guangzhou, China. 690646250@qq.com.
authors.forename: Fengliang
authors.initials: F
authors.lastname: Jin
authors.affiliation: College of Agronamy, Jiangxi Agricultural University, Nanchang, China. 1564739051@qq.com.
authors.forename: Junxi
authors.initials: J
authors.lastname: Jiang
mesh_terms: D000818:Animals; D005658:Fungi / Q000235:genetics* / Q000472:pathogenicity; D005786:Gene Expression Regulation; D006430:Hemiptera / Q000235:genetics* / Q000382:microbiology; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D051199:Toll-Like Receptor 7 / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; D051199:Toll-Like Receptor 7