An LW-Opsin Mutation Changes the Gene Expression of the Phototransduction Pathway: A Cryptochrome1 Mutation Enhances the Phototaxis of Male Plutella xylostella (Lepidoptera: Plutellidae)

SIMPLE SUMMARY: The Diamondback moth (DBM, Plutella xylostella) is a worldwide destructive pest with a typical phototaxis, mainly damaging cruciferous vegetables. Our previous study revealed that an LW-opsin mutation causes a defective phototaxis in P. xylostella, but the mechanism behind this phenomenon remains unknown. In this study, the head transcriptomes of the male Geneva 88 strain of P. xylostella (G88) and an LW-opsin mutant were compared to reveal the expression changes of other genes in the phototransduction pathway caused by the mutation of LW-opsin. The results showed that the LW-opsin mutation caused expression changes of the genes in the phototransduction pathway, such as neither inactivation nor afterpotential C (ninaC), retinal degeneration C (rdgC), arrestin1 (arr1), cryptochrome1 (cry1), transient receptor potential (trp), transient receptor potential like (trpl) and inactivation nor afterpotential D (inaD). Considering CRY1 acts as a UV/blue-light photoreceptor, the influence of a cry1 mutation on the phototaxis of P. xylostella was examined, and the results showed that the male cry1 mutant possessed higher phototactic rates to UV and blue lights than the male G88. Our results provide a foundation for further exploration of the phototransduction pathway of P. xylostella. ABSTRACT: Plutella xylostella is a typical phototactic pest. LW-opsin contributes to the phototaxis of P. xylostella, but the expression changes of other genes in the phototransduction pathway caused by the mutation of LW-opsin remain unknown. In the study, the head transcriptomes of male G88 and LW-opsin mutants were compared. A GO-function annotation showed that DEGs mainly belonged to the categories of molecular functions, biological processes, and cell composition. Additionally, a KEGG-pathway analysis suggested that DEGs were significantly enriched in some classical pathways, such as the phototransduction-fly and vitamin digestion and absorption pathways. The mRNA expressions of genes in the phototransduction-fly pathway, such as Gq, ninaC, and rdgC were significantly up-regulated, and trp, trpl, inaD, cry1, ninaA and arr1 were significantly down-regulated. The expression trends of nine DEGs in the phototransduction pathway confirmed by a RT-qPCR were consistent with transcriptomic data. In addition, the influence of a cry1 mutation on the phototaxis of P. xylostella was examined, and the results showed that the male cry1 mutant exhibited higher phototactic rates to UV and blue lights than the male G88. Our results indicated that the LW-opsin mutation changed the expression of genes in the phototransduction pathway, and the mutation of cry1 enhanced the phototaxis of a P. xylostella male, providing a basis for further investigation on the phototransduction pathway in P. xylostella.