CE02 - Milieux et biodiversité : Terre vivante

Mechanisms underlying plant adaptation and diversification in an insect crop pest – Mecadapt

Mechanisms underlying plant adaptation and diversification in an insect crop pest

Adaptation of organisms to contrasting environmental conditions is a major driver of species diversification. However we know very little on the genetic basis underlying ecologically-relevant traits, and on how and at what speed adaptive divergence leads to genetic differentiation.

MECADAPT proposes to use the continuum of divergence in the pea aphid complex to characterize the genomic architecture of adaptive divergence and to reconstruct the dynamics of genomic differentiation

Here, we will use the pea aphid, a well-suited system for adaptive genomics, which conveniently shows a complex of plant-specialized biotypes, to reconstruct the evolutionary history of plant specialization events and to identify genomic regions controlling plant specialization.

By combining novel phylogenetic and population genetic analyses of massive genomic dataset, innovative tools for functional analysis and unique biological resources, we will 1) reconstruct the evolutionary history of plant specialization and biotype formation, 2) identify genomic regions under divergent selection and characterize the genomic architecture underlying plant-based differentiation, and 3) identify genes and functions involved in plant specialization in the pea aphid complex. This project relies on a consortium of 3 French partners and 2 associate partners from other European countries who will bring complementary skills and know-how for the development of multidisciplinary approaches and combination of methods needed to reach project's objectives. This project will allow testing whether multiple independent events of adaptation to different environments involve the same genomic regions and the same set of genes and how genetic divergence accumulates along the genome through time in reproductive isolation. It will also increase knowledge on how insects overcome plant defenses and acquire new hosts on which they may become adapted, paving the way for the development of sustainable control strategies against aphids as important crop pests, based on enhanced plant defenses.

We have produced a very good assembly (at the chromosome level) of the pea aphid reference genome. We have been able to collect samples in Central Asia, allowing us to complete the geographical coverage of this species on different host plants. We initiated the characterization of the genomic divergence between biotypes and detected an introgression event. Finally, we have produced hybrid lines between different biotypes on which the detection of specialization QTLs is based.

We are currently in the process of generating new genomic resources (genomes of pea aphid lines of varied geographical origin collected from different host plants) in order to reconstruct the demographic history of the complex and to detect genomic regions associated with food specialization. We are also generating hybrid lines and will soon proceed to their phenotyping and genotyping in order to characterize specialization QTLs. Finally, we are setting up functional tools that will allow us to characterize candidate genes from population genomics and association genetics studies approaches.

Simon (2019) Genomics of plant adaptation and diversification in the pea aphid. Workshop of the international network on plant-insect-microbe interactions, Rennes, France
Simon (2019) Mechanisms of host plant adaptation and diversification in the pea aphid complex. Invited seminar at Northwest A&F University, Yangling, China
Sugio (2019) Molecular interactions of pea and the pea aphid. Invited seminar at Northwest A&F University, Yangling, China

Adaptation of organisms to contrasting environmental conditions is a major driver of species diversification. However we know very little on the genetic basis underlying ecologically-relevant traits, and on how and at what speed adaptive divergence leads to genetic differentiation. Here, we will use the pea aphid, a well-suited system for adaptive genomics, which conveniently shows a complex of plant-specialized biotypes, ranging from sympatric host races to incipient species, and resulting from a recent adaptive radiation. By combining novel phylogenetic and population genetic analyses of massive genomic dataset, innovative tools for functional analysis and unique biological resources, we will 1) reconstruct the evolutionary history of plant specialization and biotype formation, 2) identify genomic regions under divergent selection and characterize the genomic architecture underlying plant-based differentiation, and 3) identify genes and functions involved in plant specialization in the pea aphid complex. This project relies on a consortium of 3 French partners and 2 associate partners from other European countries who will bring complementary skills and know-how for the development of multidisciplinary approaches and combination of methods needed to reach project's objectives. This project will allow testing whether multiple independent events of adaptation to different environments involve the same genomic regions and the same set of genes and how genetic divergence accumulates along the genome through time in reproductive isolation. It will also increase knowledge on how insects overcome plant defenses and acquire new hosts on which they may become adapted, paving the way for the development of sustainable control strategies against aphids as important crop pests, based on enhanced plant defenses.

Project coordinator

Monsieur Jean-Christophe Simon (Institut de Génétique Environnement et Protection des Plantes)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Maynooth University / Department of Biology
ISEM Institut des Sciences de l'Evolution de Montpellier
CBGP Centre de Biologie pour la Gestion des Populations
IGEPP Institut de Génétique Environnement et Protection des Plantes

Help of the ANR 414,015 euros
Beginning and duration of the scientific project: March 2019 - 48 Months

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