Research

Context and Issues
Aphids are serious pests of many cultivated crops and mainly managed by application of pesticides. Pesticides can be harmful to the environment and human health, and many aphid species have developed resistance mechanisms against insecticides; therefore, alternative methods for aphid control are required.

Objectives
To develop durable aphid control strategies while reducing pesticide use, it is necessary to create more knowledge on plant-aphid interactions and select or construct aphid resistant crops efficiently. This project takes advantage of well-developed pea aphid (Acyrthosiphon pisum) system to study plant-aphid interactions at a molecular level. More specifically, we will examine A. pisum biotypes and host legume interactions to identify and characterize the compatibility and incompatibility factors in both aphids and plants and examine the plant signalling pathways involved in the interactions. A. pisum biotypes are specialized to feed on one or a few legume species only (compatible hosts) and cannot perform well on the other legumes (incompatible hosts). We hypothesize that plant-aphid interactions are analogous to plant-microbial pathogen interactions: aphid salivary proteins might function like effectors with virulence and avirulence functions, and their interactions with certain plant proteins determine the success of the aphids. We further hypothesize that aphid salivary proteins with biotype specific expression pattern or amino acid sequence can be the effectors involved in the determination of compatibility with specific plants and wish to test these hypotheses.

Methodology
Based on the analyses of genome re-sequencing and transcriptomic analyses, we have already identified some candidate salivary effector genes that may be involved in the aphid adaptation to their specific host plants. We would like to characterize those genes and envisage identifying their plant targets using protein-protein interactions. To directly identify the plant factors involved in aphid interactions, we have screened 240 re-sequenced Pisum sativum accessions with pea adapted and non-adapted A. pisum lines and observed a range of resistance and susceptibility. In this project, based on the already acquired data, we would like to conduct genome wide association study (GWAS) and identify the loci involved in plant resistance or susceptibility. We will also select accessions with extreme resistance/susceptible phenotype and conduct metabolomics and transcriptomics to identify the signalling pathways involved in the interactions with aphids. Furthermore, we aim to screen P. sativum mutants by TILLING to find the mutants of key resistance pathways, effector targets and resistant genes. We will test their interactions with A. pisum biotypes and examine the induction of genes and accumulation of metabolites. By the end of the project, we will produce valuable data and materials useful for both fundamental and applied researches and create the knowledge that can contribute to select or create aphid resistant crops.

Collaborations

• INRAE IPS2, Institut des Sciences des Plantes Paris Saclay : Marion Dalmais and Abdelhafid Bendahmane
• INRAE Dijon UMR 1347 Agroécologie: Richard Thompson and Christine Le-Signor
• Max Planck Institute for Chemical Ecology, Germany: Grit Kunert and Jonathan Gershenzon
• Maynooth University, Ireland: James Carolan

 Funding and Support: ANR