Acrostyle in aphid stylets: a key for crop protection – StylHook

Aphids are sap-feeding insects with piercing-sucking mouthparts. They are serious pests in agriculture and provoke significant losses, not only reducing plant growth by deprivation of nutrients, but also and most importantly because of their formidable capacity to transmit numerous plant viruses causing diseases in almost all important crops. Though difficult to quantify accurately, these losses are estimated to reduced yields in the order of several millions tons per year of fruits, vegetables, tubers and cereals, summing up to billions euros world wide, including costs related to current control measures. The majority of viruses are acquired after feeding on an infected plant and retained on the aphid’s stylet. However the specific receptors involved in viral binding are completely unknown. Viruses are transported on the stylet’s surface while the aphid moves from plant to plant. Most often, viruses are both acquired from infected plants and inoculated to healthy ones with a single probing puncture of a few seconds, thereby promoting viral outbreaks even on plants that are non-hosts for the aphids. Chemical treatments are expensive and only partially effective at preventing aphid infestation and associated viral diseases, and their intensive use have an undisputed negative impacts on human health and/or environment.
We have recently discovered the acrostyle, an organ located at the tip of aphid maxillary stylets, that harbors the receptors for Cauliflower Mosaic Virus (CaMV), and likely those for numerous other viruses. Most recently, we have identified the first protein present in the acrostyle and emerging at its surface, and we now strive to definitely demonstrate its role in plant virus transmission. The physiological function of the acrostyle is also a mystery, but it is logically expected to play a key role in plant/aphid interactions, likely by binding compounds from the plant sap or from the aphid saliva.
The goals of the StylHook project are to: (i) establish an exhaustive inventory of the cuticular proteins composing the acrostyle, (ii) define the peptide motifs accessible at the surface, (iii) identify virus receptors among these proteins, (iv) define their functions, beyond virus transmission, in the physiology of aphids, and (v) elucidate the structure of these proteins, either alone or as macromolecular complexes. Together, these goals will contribute to better understand virus/vector and plant/insect interactions at different scales including the molecular and atomic level.
Targeting and disrupting specifically the peptides at the surface of the acrostyle is a longer-term ambition for which the StylHook project aims to provide the “proof of concept”. This will pave the way for future alternative “environmentally safe” strategies to control viral spread and aphid infestation in important crops, worldwide.