The effects of glyphosate exposure on gene transcription and immune function of the silkworm, Bombyx mori.

Abstract

Glyphosate is a widely used herbicide and crop desiccant. However, whether its extensive use has any effect on the species diversity of nontarget organisms is still unclear. In this study, we used the silkworm, Bombyx mori, as the research subject, and performed RNA sequencing to analyze the transcriptional profile of silkworm midgut after exposure to glyphosate at 2975.20 mg/L (a concentration commonly used at mulberry fields). A total of 125 significantly differentially expressed genes (DEGs) were detected in the midgut of glyphosate-exposed silkworm (q < 0.05), of which 53 were upregulated and 72 were downregulated. Gene ontology enrichment analysis showed that the DEGs were mainly enriched in biological process, cellular component, and molecular function. Kyoto encyclopedia of genes and genomesanalysis showed that the differential genes were mainly related to oxidative stress, nutrient metabolism, and immune defense pathways, including oxidative stress-related Cat and Jafrac1, nutrient metabolism-related Fatp and Scpx, and immune-related CYP6AN2, UGT40B4, CTL11, serpin-2, and so forth. Experimental verification showed that glyphosate exposure led to a 4.35-fold increase in the mortality of silkworm after Beauveria bassiana infection, which might be caused by the decreased PO (phenoloxidase) activity and impaired immunity. These results provide evidence for the potential effects of residue glyphosate on the physiological functions of silkworm, and also provide a reference for the biosafety evaluation of glyphosate.