Aphid stylin cuticular proteins contribute to turnip mosaic virus (Potyvirus) transmission
Hundreds of plant viruses are transmitted by aphid vectors, among which non-circulative ones are acquired and inoculated from one host to another within seconds. These viruses are retained on receptors located at the surface of the cuticle of aphid mouthparts. Members of the Potyviridae family are the most abundant RNA viruses infecting plants, and they cause significant economic losses. Among them, viruses of the Potyvirus genus are transmitted by aphids in a stylet-borne manner. Their receptors in aphid stylets remain poorly characterized. Using turnip mosaic virus (TuMV, Potyvirus rapae) as a model, we developed complementary approaches to investigate potyvirus-aphid interactions in three vector species. Immunofluorescence detection and transmission electron microscopy revealed the presence of TuMV in the distal part of aphid maxillary stylets, both in the food canal and on the acrostyle. This cuticular organ houses Stylin proteins, including Stylin-01, the receptor for the cauliflower mosaic virus (Caulimovirus tesselobrassicae). Using CRISPR-Cas9-edited Stylin-01 mutant lines in the pea aphid, we demonstrated that this protein plays an important role in TuMV transmission. Complementary RNA interference silencing experiments revealed that Stylin-04/04bis also mediate TuMV transmission. Furthermore, our findings reveal that targeting simultaneously Stylin-01 and Stylin-04/04bis more strongly impaired the aphids ability to transmit TuMV, suggesting that virus transmission relies on a multi-component stylin interface rather than a single receptor. In conclusion, these results highlight that in complex interactions between potyviruses and their aphid vectors, Stylin proteins are key actors, underscoring their importance in the transmission of stylet-borne viruses. Author summaryPotyviruses are the largest group of plant-infecting RNA viruses and major threats to crops worldwide. Aphids can transmit them within seconds retaining virus particles on their needle-like mouthparts through specific interactions at the stylet surface. However, the identity of the aphid proteins involved in this process has remained unknown. Using turnip mosaic virus (TuMV), a potyvirus with an exceptionnally broad host ranges, we provide evidence of virus retention at the acrostyle, a specialized cuticular microstructure at the tip of aphid stylets. CRISPR-Cas9 stable aphid mutant lines and RNAi-mediated gene silencing revealed that the acrostyle cuticular proteins Stylin-01 and Stylin04/04bis promote TuMV transmission. These findings uncover previously unknown molecular components of the aphid-potyvirus interface and identify potential targets to disrupt virus-vector interaction and virus transmission.