XB-ART-56812Insects March 18, 2020; 11 (3):
Functional Characterization of Sex Pheromone Receptors in the Fall Armyworm (Spodoptera frugiperda).
Pheromone receptors (PRs) found in the antennae of male moths play a vital role in the recognition of sex pheromones released by females. The fall armyworm (FAW), Spodoptera frugiperda, is a notorious invasive pest, but its PRs have not been reported. In this report, six candidate PRs (SfruOR6, 11, 13, 16, 56 and 62) suggested by phylogenetic analysis were cloned, and their tissue-sex expression profiles were determined by quantitative real-time PCR (qPCR). All six genes except for SfruOR6 were highly and specifically expressed in the antennae, with SfruOR6, 13 and 62 being male-specific, while the other three (SfruOR11, 16 and 56) were male biased, suggesting their roles in sex pheromone perception. A functional analysis by the Xenopus oocyte system further demonstrated that SfruOR13 was highly sensitive to the major sex pheromone component Z9-14:OAc and the pheromone analog Z9,E12-14:OAc, but less sensitive to the minor pheromone component Z9-12:OAc; SfruOR16 responded weakly to pheromone component Z9-14:OAc, but strongly to pheromone analog Z9-14:OH; the other four candidate PRs did not respond to any of the four pheromone components and four pheromone analogs. This study contributes to clarifying the pheromone perception in the FAW, and provides potential gene targets for developing OR-based pest control techniques.
PubMed ID: 32197457
PMC ID: PMC7143582
Article link: Insects
Genes referenced: tcf3
Article Images: [+] show captions
|Figure 1. Alignment of the amino acid sequences of the six candidate PRs. The approximate positions of the seven predicted transmembrane domains (TM1–TM7) are indicated by black lines.|
|Figure 2. Phylogenetic analysis of ORs from four Spodoptera species. Sfru: S. frugiperda, Slitu: S. litura, Slitt: S. littoralis and Sexi: S. exigua. The six candidate PR genes in S. frugiperda are all clustered in the PR clade, and are denoted with black stars.|
|Figure 3. Tissue-sex expression profiles of six candidate SfruPR genes assessed by qPCR. An, antennae; P, proboscises; T, thoraxes; Ab, abdomens; L, legs; W, wings.|
|Figure 4. Responses of Xenopus oocytes, co-expressing SfruOR13/ORco, to sex pheromone components and analogs. (A) Inward current values of oocytes, injected with SfruOR13/ORco (upper) and with buffer (lower), induced by compounds at concentrations of 10−4 M. (B) Response profile of Xenopus oocytes expressing the SfruOR13/ORco complex. Error bars indicate SEM (n = 6). (C) Responses of Xenopus oocytes, co-expressing SfruOR13/ORco, to Z9-14:OAc at varying concentrations. (D) Dose-response curve of Xenopus oocytes, co-expressing SfruOR13/ORco, to Z9-14:OAc. EC50 value was calculated to be 6.078 × 10−6 M. Error bars indicate SEM (n = 5).|
|Figure 5. Responses of Xenopus oocytes, co-expressing SfruOR16/ORco, to sex pheromone components and analogs. (A) Inward current responses of Xenopus oocytes, injected with SfruOR16/ORco (upper) and with buffer (lower), induced compounds at concentrations of 10−4 M. (B) Response profile of Xenopus oocytes expressing SfruOR16/ORco. Error bars indicate SEM (n = 6). (C) Responses of Xenopus oocytes, co-expressing with SfruOR16/ORco, to Z9-14:OH at varying concentrations. (D) Dose-response curves of Xenopus oocytes, co-expressing SfruOR16/ORco, to Z9-14:OH. EC50 value was calculated to be 1.691 × 10−5 M. Error bars indicate SEM (n = 5).|
|Figure 6. Response profiles of PRs from four Spodoptera species. The left part is the phylogenetic tree of candidate PRs from the four species. The right is the response profiles of these candidate PRs (S. frugiperda (Figure 4 and Figure 5), S. exigua , S. littoralis [15,69], and S. litura ). The dots represent the responses obtained by the Xenopus oocytes system, and the stars represent responses by in vivo heterologous expression in Drosophila OSNs. The blanks indicate compounds that are not tested. The color of the pheromone component corresponds to the color of the insect species to which the sex pheromone belongs, and the black refers to the components shared by two or more species. Z9-14:OAc is shared by the four Spodoptera species; Z9,E12-14:OAc is shared by S. litura, S. littoralis and S. exigua; Z9,E11-14:OAc and E11-14:OAc are shared by S. litura and S. littoralis. Z11-16:OH and Z9-16:Ald in gray are not sex pheromones for the four Spodoptera species.|
References [+] :
Bastin-Héline, A novel lineage of candidate pheromone receptors for sex communication in moths. 2020, Pubmed, Xenbase