Are saliva proteins key determinants of host plant specificity in the pea aphid complex?

Research

Context

Aphids are insect pests that feed on plant phloem sap and cause feeding damages and transmission of plant pathogens. The pea aphid (Acyrthosiphon pisum) complex is consisted of multiple biotypes each of which specialized to one or a few specific legume plants. Aphids use a specialized mouth part to puncture plant phloem sieve cells and suck plant nutrients. During the feeding process, aphids secrete saliva which contains various proteins that might interact with plant proteins.

Objectives

This project aims to examine the roles of aphid salivary proteins in host plant adaptation. Based on previous works in plant microbe interactions, I hypothesize that aphid saliva proteins function like microbial pathogen effectors. Thus, I anticipate that the saliva proteins that are involved in host adaptation process are under high evolutionary pressure and show polymorphisms between biotypes.

Methodology

We will examine pool-seq data of aphid genomes (3 biotypes, 60 individual aphids/pool) to identify fast evolving salivary genes. Furthermore, we will conduct in-depth analysis of published and unpublished salivary proteomes and transcriptomes to extend the catalogue of the pea aphid salivary genes. The fast evolving salivary genes will be expressed in host/non host plants or silenced in aphids to examine their involvement in specific plant-aphid interactions.

Perspectives

The in-depth study of the pea aphid salivary genes will be extended to understand the evolutionary history of salivary genes in each aphid species. Functional analyses of salivary proteins will increase our knowledge on plant-aphid interactions at a molecular level and contribute to create/construct aphid resistant/tolerant crops.

Funding and Support

• European Commission (100k€)
• INRA SPE and Région Bretagne