Molecular characterization and functional analysis of Cry toxin receptor‐like genes from the model insect Galleria mellonella

Abstract

Crystal (Cry) toxins produced from the soil bacterium, Bacillus thuringiensis (Bt), have gained worldwide attention for long due to their insecticidal potential. A number of receptor proteins located on the epithelial cells of the larval midgut were shown to be crucial for Cry intoxication in different insect pests belonging to order Lepidoptera, Diptera and Coleoptera. A beehive pest, Galleria mellonella, serves as an excellent insect model for biochemical research. However, information on the Cry receptor‐like genes in G. mellonella is limited. In the present study, the full‐length sequences of four putative Cry receptor genes (ABC transporter, alkaline phosphatase, aminopeptidase N and cadherin) were cloned from G. mellonella. All these receptor genes were substantially upregulated in the midgut tissue of fourth‐instar G. mellonella larvae upon early exposure (6 h) to a sub‐lethal dose of Cry1AcF toxin. Oral and independent delivery of bacterially‐expressed dsRNAs corresponding to four receptor genes in G. mellonella suppressed the transcription of target receptors which in turn significantly reduced the larval sensitivity to Cry1AcF toxin. As the laboratory populations of G. mellonella develop Bt resistance in a relatively short time, molecular characterization of Cry receptor genes in G. mellonella performed in the present study may provide some useful information for future research related to the genetic basis of Bt resistance in the model insect.

RNAi-mediated knockdown of gut receptor-like genes prohibitin and α-amylase altered the susceptibility of Galleria mellonella to Cry1AcF toxin

“…With few exceptions majority of these candidate genes were predominantly transcribed in the midgut tissues and fourthinstar larval stages of G. mellonella. This is in agreement with our previous finding that G. mellonella fourth-instar stage is most vulnerable to Cry1AcF-induced toxicity and Cry1AcF enzymatic action occurs in midgut epithelium as revealed by the histopathology assay [21]. The nonreceptor gene arylphorin was greatly expressed in the fifth-instar stage of G. mellonella in the current study.…”

“…have been shown to be involved in Cry intoxication process in different insects [7,[16][17][18][19][20]. In our earlier study, the independent and significant role of G. mellonella CAD, ALP, APN1 and ABCC2 receptors in Cry intoxication process was established [21]. In the present study, we interrogated the role of prohibitin, GLTP, α-amylase, ADAM and UDP-GT in Cry-induced toxicity in G. mellonella.…”

Greater wax moth control in apiaries can be improved by combining Bacillus thuringiensis and entrapments

“…Histopathology assays were carried out according to a previous description 68 . The 4th instar GWM larvae were injected with 10 μL BiotGm (100 μg/mL) or PBS as the treatment group and control group, respectively.…”