The Combination of Bacillus Thuringiensis and Its Engineered Strain Expressing dsRNA Increases the Toxicity against Plutella Xylostella.

Ying-Xia Jiang,Xue-Mei Chu,Peng-Rong Huang,Guang Yang,Jin-Zhi Chen,Jing Chen,Ben-Hu Zha,Miao-Wen Li

doi:10.3390/ijms23010444

Abstract

RNA interference (RNAi) has been developed and used as an emerging strategy for pest management. Here, an entomopathogen Bacillus thuringiensis (Bt) was used to express the dsRNA for the control of Plutella xylostella. A vector containing a 325-bp fragment of the conserved region of P. xylostella arginine kinase gene (PxAK) flanking in two ends with the promoter Pro3α was developed and transferred into Bt 8010 and BMB171, and consequently engineered Bt strains 8010AKi and BMB171AKi expressing dsRNA of PxAK were developed. The two engineered Bt strains were separately mixed with Bt 8010 in a series of ratios, and then fed to the P. xylostella larvae. We found that 8010:8010AKi of 9:1 and 8010:BMB171AKi of 7:3 caused a higher mortality than Bt 8010. PxAK expression levels in the individuals treated with the mixtures, 8010AKi and BMB171Aki, were lower than that in the control. The intrinsic rate of increase (r) and net reproductive rate (R0) of the population treated with 8010:8010AKi of 9:1 were lower than those of the population treated with Bt 8010 or 8010AKi. We developed a Bt-mediated insect RNAi for the control of P. xylostella and demonstrated a practical approach to integrating the entomopathogen with RNAi technique for the pest management.

Highlights

RNA interference (RNAi) is a potential genetic tool for pest management [1,2,3]
Reports state that the survival rates of Spodoptera exigua Hübner (Lepidoptera: Noctuidae)feeding on E. coli HT115 expressing double-strand RNA (dsRNA) of chitin synthase gene A (SeCHSA) is lower than that of individuals feeding on controls [10]
The pHT305AKR2 plasmid was transformed into Bacillus thuringiensis (Bt) 8010 and BMB171 to produce engineered bacteria 8010AKi and BMB171AKi (Figure S1c)

Summary

Introduction

It has been proven that transgenic plants/microorganism expressing double-strand RNA (dsRNA) of insect pest gene(s) can disturb the insect growth and development, and even lead to death [4,5]. Xu-142 [7], and Arabidopsis thaliana (Linnaeus) Heynhold [8,9] Another efficient way of using RNAi technology to control insect pests is through the engineered bacteria expressing dsRNA. Among these engineered bacteria, the Escherichia coli (Migula) Castellani and Chalmers strain HT115, which is deficient in RNase III enzyme, is used to produce dsRNA [10,11]. With the help of p19, a siRNA-binding protein, both wild type E. coli and HT115 with RNase III expression restored can accumulate a mass of siRNAs to achieve an efficient interference [16]

Methods

Results

Conclusion