Molecular characterization of the insecticidal activity of double-stranded RNA targeting the smooth septate junction of western corn rootworm (Diabrotica virgifera virgifera)

Abstract

The western corn rootworm (WCR, Diabrotica virgifera virgifera) gene, dvssj1, is a putative homolog of the Drosophila melanogaster gene, snakeskin (ssk). This gene encodes a membrane protein associated with the smooth septate junction (SSJ) which is required for the proper barrier function of the epithelial lining of insect intestines. Disruption of DVSSJ integrity by RNAi technique has been shown previously to be an effective approach for corn rootworm control, by apparent suppression of production of DVSSJ1 protein leading to growth inhibition and mortality. To understand the mechanism that leads to the death of WCR larvae by dvssj1 double-stranded RNA, we examined the molecular characteristics associated with SSJ functions during larval development. Dvssj1 dsRNA diet feeding results in dose-dependent suppression of mRNA and protein; this impairs SSJ formation and barrier function of the midgut and results in larval mortality. These findings suggest that the malfunctioning of the SSJ complex in midgut triggered by dvssj1 silencing is the principal cause of WCR death. This study also illustrates that dvssj1 is a midgut-specific gene in WCR and its functions are consistent with biological functions described for ssk.

Characterization of DvSSJ1 transcripts targeting the smooth septate junction (SSJ) of western corn rootworm (Diabrotica virgifera virgifera)

“…These findings support that the malfunction of SSJ complexes in the midgut triggered by DvSSJ1 RNAi were the main effects leading to the death of WCR. The DvSSJ1 is a midgut-specific gene in WCR and its functions are consistent with the biological functions described for Drosophila 9 . Two forms of transgenic DvSSJ1 dsRNAs present in plant tissues are long dsRNAs and siRNAs 8 .…”

“…from WCR 9 . These proteins play a crucial role in maintaining tissue homeostasis through the regulation of stem cell proliferation and enterocyte behavior in the Drosophila adult midgut 11 .…”

“…These proteins play a crucial role in maintaining tissue homeostasis through the regulation of stem cell proliferation and enterocyte behavior in the Drosophila adult midgut 11 . When the western corn rootworm feeds on DvSSJ1 dsRNA, the smooth septate junction gene is down-regulated by the insect's RNAi machinery resulting in pest mortality 9 .…”

“…Transgenic plants expressing dsRNA targeting DvSSJ1 show insecticidal activity and significant plant protection from WCR damage 8 . Diet based insect feeding assays using dsRNA targeting DvSSJ1 mRNA demonstrate that SSJ protein accumulation and mortality was negatively correlated and that the interactions of SSJ proteins and barrier function are impaired in RNAi-compromised or knockout insects 9 . These findings support that the malfunction of SSJ complexes in the midgut triggered by DvSSJ1 RNAi were the main effects leading to the death of WCR.…”

Validating the Potential of Double-Stranded RNA Targeting Colorado Potato Beetle Mesh Gene in Laboratory and Field Trials

“…In western corn rootworm, Hu et al (2016) identified another target gene-mesh (alternatively named dvssj2) which encodes a smooth septate junction protein important for structural integrity of the midgut epithelium. They showed that silencing mesh impairs midgut barrier function which results in increased larval mortality (Hu et al, 2019).…”