Roles of GOBP1 in perception of host plant volatiles revealed by CRISPR/Cas9-mediated mutagenesis in Spodoptera litura

The general odorant-binding proteins (GOBPs) in Lepidoptera form a distinct OBP subclass, which exclusively has two members (GOBP1 and GOBP2) in a single species. GOBPs are long thought to function in perception of plant odorants and recently in sex pheromones, but the in vivo evidence is rarely provided. Here, by using CRISPR/Cas9 technique, we demonstrated that GOBP1 in a noctuid moth Spodoptera litura is involved in perception of host plant volatiles but not of the female sex pheromone, and GOBP1 in females is less important than GOBP2 in host plant perception. First, the GOBP1 knockout strain (GOBP1(-/-)) of S. litura was obtained by CRISPR/Cas9 technique. Second, in the electroantennography (EAG) tests, GOBP1(-/-) females displayed significant reduction in responses to plant volatile farnesene, and leaf discs of the host plant cabbage (males only to high leaf doses), but GOBP1(-/-) adults did not show significant EAG reduction to the major sex pheromone component and two pheromone analogues. Third, compared with GOBP2(-/-) females, GOBP1(-/-) females were significantly lower in reduction (in relation to WT moths) of EAG response to host plant leaves. Our results provide in vivo evidence that GOBP1 is involved in perception of host plant volatiles but is less important than GOBP2 in S. litura.