Identification of Plant Virus Receptor Candidates in the Stylets of Their Aphid Vectors
Résumé
Plant viruses transmitted by insects cause tremendous losses in most important crops around the world. The identification of receptors of plant viruses within their insect vectors is a key challenge to understanding the mechanisms of transmission and offers an avenue for future alternative control strategies to limit viral spread. We here report the identification of two cuticular proteins within aphid mouthparts, and we provide experimental support for the role of one of them in the transmission of a non-circulative virus. These two proteins, named Stylin-01 and Stylin-02, belong to the RR-1 cuticular protein subfamily and are highly conserved among aphid species. Using an im-munolabeling approach, they were localized in the maxillary stylets of the pea aphid Acyrthosiphon pisum and the green peach aphid Myzus persicae, in the acrostyle, an organ earlier shown to harbor receptors of a noncirculative virus. A peptide motif present at the C termini of both Stylin-01 and Stylin-02 is readily accessible all over the surface of the acrostyle. Competition for in vitro binding to the acrostyle was observed between an antibody targeting this peptide and the helper component protein P2 of Cauliflower mosaic virus. Furthermore, silencing the stylin-01 but not stylin-02 gene through RNA interference decreased the efficiency of Cauliflower mosaic virus transmission by Myzus per-sicae. These results identify the first cuticular proteins ever reported within arthropod mouthparts and distinguish Stylin-01 as the best candidate receptor for the aphid transmission of noncirculative plant viruses.
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