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Jeanchristophe Simon - One of the best experts on this subject based on the ideXlab platform.
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Protective symbiosis: distribution of Hamiltonella defensa in natural populations of Pea Aphid
2020Co-Authors: Mélanie Leclair, Jeanpierre Gauthier, Jeanchristophe Simon, Inès Pons-guillouard, Frédérique Mahéo, Gregory Toussaint, Jean-françois Le Gallic, Yannick OutremanAbstract:Symbiotic associations between microorganisms and eukaryotes are common in nature. These microorganisms can play important role of the evolution and ecology of their hosts by modifying their phenotype like conferring protection against parasitic wasps. This symbiotic protection is encountered in the Pea Aphid, Acyrthosiphon pisum, where the bacterial symbiont Hamiltonella defensa confers protection against parasitoid wasp, Aphidius ervi. Despite this protective benefit, this symbiont occurs only at intermediate frequencies in natural populations. To identify factors influencing the frequency of H. defensa in natural population, we measured Pea Aphid life history traits and the protective effect of this symbiont. We found that protective symbiont doesn’t influence the host life history traits and the protection conferred by this symbiont varies according the biotype of Pea Aphid and the bacterial strain. However, the multiple infections with facultative symbionts reduce the fitness of the host while increasing protection against parasitoids. We also observed the positive correlation between Aphid reproduction in the absence of parasitoid and the level of resistance: higher the symbiotic protection higher the Aphid fecundity. This finding has important implications for the evolution of defensive symbiosis and allows evidence the need for better understanding of how these protective symbionts is maintained in the population.
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Host plant effects on the outcomes of defensive symbioses in the Pea Aphid complex
Evolutionary Ecology, 2019Co-Authors: Corentin Sochard, Jeanchristophe Simon, Mélanie Leclair, Yannick OutremanAbstract:There is increasing evidence that microbial symbionts play pivotal roles in protecting their hosts. Most studies on defensive symbioses have analyzed interaction effects of host-symbiont genotypes on fitness value of defense but very few have considered how local environment could influence symbiont-mediated phenotypes. Our study assessed the effects of environmental variation on the intensity and cost of protection against adverse organisms in lineages of the Pea Aphid, Acyrthosiphon pisum differing by their composition in secondary symbionts. This Aphid is frequently infected by Hamiltonella defensa, singly or in co-infection with Fukatsuia symbiotica, and both bacterial symbionts generally confer a resistance against parasitoids but also induce fitness costs to their hosts. The Pea Aphid forms a complex of plant-adapted biotypes, each specialized on one or a few legume species (i.e., native host). These biotypes can all feed on broad bean, considered as a “universal” host plant. Since plants constitute the primary environment of Aphids in providing both habitat and resources, we tested if symbiont-mediated protection was influenced by whether plant-specialized Aphids fed on their native or universal hosts. For this purpose, parasitism resistance as well as constitutive and induced fitness costs of 21 Pea Aphid lineages differing in biotype and symbiotic complement were measured on both native and universal host plants. We showed that host plant could exert some influence on the outcomes of symbiotic defenses: while the host plant species had very little effect on the protection level against parasitoids, we showed that both costs of symbiotic association and costs induced by parasitism challenge varied in a plant-dependent manner.
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Multi-scale characterization of symbiont diversity in the Pea Aphid complex through metagenomic approaches.
Microbiome, 2018Co-Authors: Cervin Guyomar, Fabrice Legeai, Emmanuelle Jousselin, Christophe Mougel, Claire Lemaitre, Jeanchristophe SimonAbstract:Most metazoans are involved in durable relationships with microbes which can take several forms, from mutualism to parasitism. The advances of NGS technologies and bioinformatics tools have opened opportunities to shed light on the diversity of microbial communities and to give some insights into the functions they perform in a broad array of hosts. The Pea Aphid is a model system for the study of insect-bacteria symbiosis. It is organized in a complex of biotypes, each adapted to specific host plants. It harbors both an obligatory symbiont supplying key nutrients and several facultative symbionts bringing additional functions to the host, such as protection against biotic and abiotic stresses. However, little is known on how the symbiont genomic diversity is structured at different scales: across host biotypes, among individuals of the same biotype, or within individual Aphids, which limits our understanding on how these multi-partner symbioses evolve and interact. We present a framework well adapted to the study of genomic diversity and evolutionary dynamics of the Pea Aphid holobiont from metagenomic read sets, based on mapping to reference genomes and whole genome variant calling. Our results revealed that the Pea Aphid microbiota is dominated by a few heritable bacterial symbionts reported in earlier works, with no discovery of new microbial associates. However, we detected a large and heterogeneous genotypic diversity associated with the different symbionts of the Pea Aphid. Partitioning analysis showed that this fine resolution diversity is distributed across the three considered scales. Phylogenetic analyses highlighted frequent horizontal transfers of facultative symbionts between host lineages, indicative of flexible associations between the Pea Aphid and its microbiota. However, the evolutionary dynamics of symbiotic associations strongly varied depending on the symbiont, reflecting different histories and possible constraints. In addition, at the intra-host scale, we showed that different symbiont strains may coexist inside the same Aphid host. We present a methodological framework for the detailed analysis of NGS data from microbial communities of moderate complexity and gave major insights into the extent of diversity in Pea Aphid-symbiont associations and the range of evolutionary trajectories they could take.
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differential gene expression according to race and host plant in the Pea Aphid
Molecular Ecology, 2016Co-Authors: Isobel Eyres, Fabrice Legeai, Jeanchristophe Simon, Julie Jaquiery, Ludovic Duvaux, Karim Gharbi, Jingjiang Zhou, Akiko Sugio, Michaela Nelson, Carole M SmadjaAbstract:Host-race formation in phytophagous insects is thought to provide the opportunity for local adaptation and subsequent ecological speciation. Studying gene expression differences amongst host races may help to identify phenotypes under (or resulting from) divergent selection and their genetic, molecular and physiological bases. The Pea Aphid (Acyrthosiphon pisum) comprises host races specializing on numerous plants in the Fabaceae and provides a unique system for examining the early stages of diversification along a gradient of genetic and associated adaptive divergence. In this study, we examine transcriptome-wide gene expression both in response to environment and across Pea Aphid races selected to cover the range of genetic divergence reported in this species complex. We identify changes in expression in response to host plant, indicating the importance of gene expression in Aphid-plant interactions. Races can be distinguished on the basis of gene expression, and higher numbers of differentially expressed genes are apparent between more divergent races; these expression differences between host races may result from genetic drift and reproductive isolation and possibly divergent selection. Expression differences related to plant adaptation include a subset of chemosensory and salivary genes. Genes showing expression changes in response to host plant do not make up a large portion of between-race expression differences, providing confirmation of previous studies' findings that genes involved in expression differences between diverging populations or species are not necessarily those showing initial plasticity in the face of environmental change.
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diversity in symbiont consortia in the Pea Aphid complex is associated with large phenotypic variation in the insect host
Evolutionary Ecology, 2016Co-Authors: Jeanchristophe Simon, Mélanie Leclair, Frédérique Mahéo, Ines Pons, Stephanie Morliere, Yannick OutremanAbstract:Virtually all eukaryotes host microbial symbionts that influence their phenotype in many ways. In a host population, individuals may differ in their symbiotic complement in terms of symbiont species and strains. Hence, the combined expression of symbiont and host genotypes may generate a range of phenotypic diversity on which selection can operate and influence host population ecology and evolution. Here, we used the Pea Aphid to examine how the infection with various symbiotic complements contributes to phenotypic diversity of this insect species. The Pea Aphid hosts an obligate symbiont (Buchnera Aphidicola) and several secondary symbionts among which is Hamiltonella defensa. This secondary symbiont confers a protection against parasitoids but can also reduce the host’s longevity and fecundity. These phenotypic effects of H. defensa infection have been described for a small fraction of the Pea Aphid complex which encompasses multiple plant-specialized biotypes. In this study, we examined phenotypic differences in four Pea Aphid biotypes where H. defensa occurs at high frequency and sometimes associated with other secondary symbionts. For each biotype, we measured the fecundity, lifespan and level of parasitoid protection in several Aphid lineages differing in their symbiotic complement. Our results showed little variation in longevity and fecundity among lineages but strong differences in their protection level. These differences in protective levels largely resulted from the strain type of H. defensa and the symbiotic consortium in the host. This study highlights the important role of symbiotic complement in the emergence of phenotypic divergence among host populations of the same species.
Shuji Shigenobu - One of the best experts on this subject based on the ideXlab platform.
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genomic revelations of a mutualism the Pea Aphid and its obligate bacterial symbiont
Cellular and Molecular Life Sciences, 2011Co-Authors: Shuji Shigenobu, Alex C C WilsonAbstract:The symbiosis of the Pea Aphid Acyrthosphion pisum with the bacterium Buchnera Aphidicola APS represents the best-studied insect obligate symbiosis. Here we present a refined picture of this symbiosis by linking pre-genomic observations to new genomic data that includes the complete genomes of the eukaryotic and prokaryotic symbiotic partners. In doing so, we address four issues central to understanding the patterns and processes operating at the A. pisum/Buchnera APS interface. These four issues include: (1) lateral gene transfer, (2) host immunity, (3) symbiotic metabolism, and (4) regulation.
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Aphidbase a centralized bioinformatic resource for annotation of the Pea Aphid genome
Insect Molecular Biology, 2010Co-Authors: Fabrice Legeai, Stephen Richards, Alex C C Wilson, C Rispe, Jeanpierre Gauthier, Shuji Shigenobu, John K Colbourne, Olivier Collin, Terence MurphyAbstract:AphidBase is a centralized bioinformatic resource that was developed to facilitate community annotation of the Pea Aphid genome by the International Aphid Genomics Consortium (IAGC). The AphidBase Information System designed to organize and distribute genomic data and annotations for a large international community was constructed using open source software tools from the Generic Model Organism Database (GMOD). The system includes Apollo and GBrowse utilities as well as a wiki, blast search capabilities and a full text search engine. AphidBase strongly supported community cooperation and coordination in the curation of gene models during community annotation of the Pea Aphid genome. AphidBase can be accessed at http://www.Aphidbase.com.
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a full length cdna resource for the Pea Aphid acyrthosiphon pisum
Insect Molecular Biology, 2010Co-Authors: Stephen Richards, Richard A Gibbs, Shuji Shigenobu, Andrew Cree, Mizue Morioka, Takema Fukatsu, Toshiaki Kudo, Shinya Miyagishima, David L SternAbstract:Large collections of full-length cDNAs are important resources for genome annotation and functional genomics. We report the creation of a collection of 50 599 full-length cDNA clones from the Pea Aphid, Acyrthosiphon pisum. Sequencing from 5′ and 3′ ends of the clones generated 97 828 high-quality expressed sequence tags, representing approximately 9000 genes. These sequences were imported to AphidBase and are shown to play crucial roles in both automatic gene prediction and manual annotation. Our detailed analyses demonstrated that the full-length cDNAs can further improve gene models and can even identify novel genes that are not included in the current version of the official gene set. This full-length cDNA collection can be utilized for a wide variety of functional studies, serving as a community resource for the study of the functional genomics of the Pea Aphid.
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chitinase like proteins encoded in the genome of the Pea Aphid acyrthosiphon pisum
Insect Molecular Biology, 2010Co-Authors: Atsushi Nakabachi, Shuji Shigenobu, Shinya MiyagishimaAbstract:In insects, chitinases play an essential role in the degradation of old exoskeleton and turnover of the gut lining. In silico screening of the entire genome of the Pea Aphid (Hemimetabola), Acyrthosiphon pisum, detected nine genes encoding putative chitinase-like proteins, including six enzymatically active chitinases, one imaginal disc growth factor, and one endo-beta-N-acetylglucosaminidase. Screening of the genomes of Aedes aegypti, Anopheles gambiae, Apis mellifera, Bombyx mori, Culex quinquefasciatus, Drosophila melanogaster, Nasonia vitripennis, Pediculus humanus corporis, and Tribolium castaneum suggested rePeated gene duplications in holometabolous lineages. Quantitative reverse transcription-PCR demonstrated the expression of four and two distinct chitinase-like genes of A. pisum to be highly up-regulated in the embryo and the midgut, respectively, suggesting specific roles in these Pea Aphid tissues.
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comprehensive survey of developmental genes in the Pea Aphid acyrthosiphon pisum frequent lineage specific duplications and losses of developmental genes
Insect Molecular Biology, 2010Co-Authors: Jennifer A Brisson, Shuji Shigenobu, Ryan D. Bickel, Thomas Butts, C C Chang, Olivier Christiaens, Gregory K Davis, Elizabeth J Duncan, David E K FerrierAbstract:Aphids exhibit unique attributes, such as polyphenisms and specialized cells to house endosymbionts, that make them an interesting system for studies at the interface of ecology, evolution and development. Here we present a comprehensive characterization of the developmental genes in the Pea Aphid, Acyrthosiphon pisum, and compare our results to other sequenced insects. We investigated genes involved in fundamental developmental processes such as establishment of the body plan and organogenesis, focusing on transcription factors and components of signalling pathways. We found that most developmental genes were well conserved in the Pea Aphid, although many lineage-specific gene duplications and gene losses have occurred in several gene families. In particular, genetic components of transforming growth factor beta (TGFβ) Wnt, JAK/STAT (Janus kinase/signal transducer and activator of transcription) and EGF (Epidermal Growth Factor) pathways apPear to have been significantly modified in the Pea Aphid.
Jean Peccoud - One of the best experts on this subject based on the ideXlab platform.
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genetic characterisation of new host specialised biotypes and novel associations with bacterial symbionts in the Pea Aphid complex
Insect Conservation and Diversity, 2015Co-Authors: Jean Peccoud, Manon De La Huerta, Cindy Laurence, Frédérique Mahéo, Jeanchristophe SimonAbstract:1. The Pea Aphid, Acyrthosiphon pisum Harris, constitutes a complex of sympatric populations that are specialised to distinct species of Fabaceae. So far, 12 such populations have been characterised genetically as genetic clusters associated with one or few legumes species. These clusters form a continuum of genetic divergence linking host-associated races, which show moderate hybridization, to nascent species. They are also known to be associated with different species of endosymbiotic bacteria, which have environmentally dependent effects on Aphid fitness2. Here, we report on the genetic characterisation of new host-associated populations in this species complex. We sampled Pea Aphids in eastern France on Genista tinctoria, G. sagittalis, Onobrychis viciifolia, and Hippocrepis comosa. Bayesian clustering methods based on genotypes obtained at 25 microsatellite loci showed that each sampled plant species hosted a specific Pea Aphid population. Comparison with previously characterised biotypes showed that the population associated with Hippocrepis comosa was no different from that on Securigera varia. Migrant Aphids from other host plants and hybrids were found at various frequencies on the newly sampled plant species. They were particularly frequent on Onobrychis viciifolia, occasional between the two Genista-associated populations, and rare on Hippocrepis comosa.3. PCR-based screening of bacterial species revealed new associations between Aphid biotypes and facultative endosymbionts, chiefly the combination of Serratia symbiotica and Hamiltonella defensa within most individuals collected on Genista.4. The newly identified biotypes, which add up to a total of 15 within the Pea Aphid complex, offer new material to study the mechanisms and genetic bases of host-specialisation and ecological speciation in this model Aphid.
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widespread host dependent hybrid unfitness in the Pea Aphid species complex
Evolution, 2014Co-Authors: Jean Peccoud, Joel Bonhomme, Yannick Outreman, Manon De La Huerta, Cindy Laurence, Carole M Smadja, Jeanchristophe SimonAbstract:: Linking adaptive divergence to hybrid unfitness is necessary to understand the ecological factors contributing to reproductive isolation and speciation. To date, this link has been demonstrated in few model systems, most of which encompass ecotypes that occupy relatively early stages in the speciation process. Here we extend these studies by assessing how host-plant adaptation conditions hybrid fitness in the Pea Aphid, Acyrthosiphon pisum. We made crosses between and within five Pea Aphid biotypes adapted to different host plants and representing various stages of divergence within the complex. Performance of F1 hybrids and nonhybrids was assessed on a "universal" host that is favorable to all Pea Aphid biotypes in laboratory conditions. Although hybrids performed equally well as nonhybrids on the universal host, their performance was much lower than nonhybrids on the natural hosts of their parental populations. Hence, hybrids, rather than being intrinsically deficient, are maladapted to their parents' hosts. Interestingly, the impact of this maladaptation was stronger in certain hybrids from crosses involving the most divergent biotype, suggesting that host-dependent postzygotic isolation has continued to evolve late in divergence. Even though host-independent deficiencies are not excluded, hybrid maladaptation to parental hosts supports the hypothesis of ecological speciation in this complex.
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inheritance patterns of secondary symbionts during sexual reproduction of Pea Aphid biotypes
Insect Science, 2014Co-Authors: Jean Peccoud, Joel Bonhomme, Manon De La Huerta, Frédérique Mahéo, Olivier Cosson, Jeanchristophe SimonAbstract:Herbivorous insects frequently harbor bacterial symbionts that affect their ecology and evolution. Aphids host the obligatory endosymbiont Buchnera, which is required for reproduction, together with facultative symbionts whose frequencies vary across Aphid populations. These maternally transmitted secondary symbionts have been particularly studied in the Pea Aphid, Acyrthosiphon pisum, which harbors at least 8 distinct bacterial species (not counting Buchnera) having environmentally dependent effects on host fitness. In particular, these symbiont species are associated with Pea Aphid populations feeding on specific plants. Although they are maternally inherited, these bacteria are occasionally transferred across insect lineages. One mechanism of such nonmaternal transfer is paternal transmission to the progeny during sexual reproduction. To date, transmission of secondary symbionts during sexual reproduction of Aphids has been investigated in only a handful of Aphid lineages and 3 symbiont species. To better characterize this process, we investigated inheritance patterns of 7 symbiont species during sexual reproduction of Pea Aphids through a crossing experiment involving 49 clones belonging to 9 host-specialized biotypes, and 117 crosses. Symbiont species in the progeny were detected with diagnostic qualitative PCR at the fundatrix stage hatching from eggs and in later parthenogenetic generations. We found no confirmed case of paternal transmission of symbionts to the progeny, and we observed that maternal transmission of a particular symbiont species (Serratia symbiotica) was quite inefficient. We discuss these observations in respect to the ecology of the Pea Aphid.
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post pleistocene radiation of the Pea Aphid complex revealed by rapidly evolving endosymbionts
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Jean Peccoud, Jeanchristophe Simon, Heather J Mclaughlin, Nancy A MoranAbstract:Adaptation to different resources has the potential to cause rapid species diversification, but few studies have been able to quantify the time scale of recent adaptive radiations. The Pea Aphid, Acyrthosiphon pisum, a model of speciation for host-specialized parasites, consists of several biotypes (races or species) living on distinct legume hosts. To document this radiation, we used rapidly evolving sequences from Buchnera, the maternally transmitted bacterial endosymbiont of Aphids. Analyses of Buchnera pseudogene sequences revealed that 11 host-associated biotypes sort mostly into distinct matrilines despite low sequence divergence. A calibration based on divergence times of 7 sequenced genomes of Buchnera allowed us to date the last maternal ancestor of these biotypes between 8,000 and 16,000 years, with a burst of diversification at an estimated 3,600–9,500 years. The recency of this diversification, which is supported by microsatellite data, implies that the Pea Aphid complex ranks among the most rapid adaptive radiations yet documented. This diversification coincides with post-Pleistocene warming and with the domestication and anthropogenic range expansion of several of the legume hosts of Pea Aphids. Thus, we hypothesize that the new availability or abundance of resources triggered a cascade of divergence events in this newly formed complex.
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a continuum of genetic divergence from sympatric host races to species in the Pea Aphid complex
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Jean Peccoud, Manuel Plantegenest, Anthony Ollivier, Jeanchristophe SimonAbstract:Sympatric populations of insects adapted to different host plants, i.e., host races, are good models to investigate how natural selection can promote speciation in the face of ongoing gene flow. However, host races are documented in very few model systems and their gradual evolution into good species, as assumed under a Darwinian view of species formation, lacks strong empirical support. We aim at resolving this uncertainty by investigating host specialization and gene flow among populations of the Pea Aphid complex, Acyrthosiphon pisum. Genetic markers and tests of host plant specificity indicate the existence of at least 11 well-distinguished sympatric populations associated with different host plants in Western Europe. Population assignment tests show variable migration and hybridization rates among sympatric populations, delineating 8 host races and 3 possible species. Notably, hybridization correlates negatively with genetic differentiation, forming a continuum of population divergence toward virtually complete speciation. The Pea Aphid complex thus illustrates how ecological divergence can be sustained among many hybridizing populations and how insect host races blend into species by gradual reduction of gene flow.
Alex C C Wilson - One of the best experts on this subject based on the ideXlab platform.
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genomic revelations of a mutualism the Pea Aphid and its obligate bacterial symbiont
Cellular and Molecular Life Sciences, 2011Co-Authors: Shuji Shigenobu, Alex C C WilsonAbstract:The symbiosis of the Pea Aphid Acyrthosphion pisum with the bacterium Buchnera Aphidicola APS represents the best-studied insect obligate symbiosis. Here we present a refined picture of this symbiosis by linking pre-genomic observations to new genomic data that includes the complete genomes of the eukaryotic and prokaryotic symbiotic partners. In doing so, we address four issues central to understanding the patterns and processes operating at the A. pisum/Buchnera APS interface. These four issues include: (1) lateral gene transfer, (2) host immunity, (3) symbiotic metabolism, and (4) regulation.
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genomic insight into the amino acid relations of the Pea Aphid acyrthosiphon pisum with its symbiotic bacterium buchnera Aphidicola
Insect Molecular Biology, 2010Co-Authors: Alex C C Wilson, Peter D Ashton, Federica Calevro, Hubert Charles, Stefano Colella, Gerard Febvay, Georg Jander, P F Kushlan, Sandy J Macdonald, J F SchwartzAbstract:The Pea Aphid genome includes 66 genes contributing to amino acid biosynthesis and 93 genes to amino acid degradation. In several respects, the Pea Aphid gene inventory complements that of its symbiotic bacterium, Buchnera Aphidicola (Buchnera APS). Unlike other insects with completely sequenced genomes, the Pea Aphid lacks the capacity to synthesize arginine, which is produced by Buchnera APS. However, consistent with other insects, it has genes coding for individual reactions in essential amino acid biosynthesis, including threonine dehydratase and branched-chain amino acid aminotransferase, which are not coded in the Buchnera APS genome. Overall the genome data suggest that the biosynthesis of certain essential amino acids is shared between the Pea Aphid and Buchnera APS, providing the opportunity for precise Aphid control over Buchnera metabolism.
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Aphidbase a centralized bioinformatic resource for annotation of the Pea Aphid genome
Insect Molecular Biology, 2010Co-Authors: Fabrice Legeai, Stephen Richards, Alex C C Wilson, C Rispe, Jeanpierre Gauthier, Shuji Shigenobu, John K Colbourne, Olivier Collin, Terence MurphyAbstract:AphidBase is a centralized bioinformatic resource that was developed to facilitate community annotation of the Pea Aphid genome by the International Aphid Genomics Consortium (IAGC). The AphidBase Information System designed to organize and distribute genomic data and annotations for a large international community was constructed using open source software tools from the Generic Model Organism Database (GMOD). The system includes Apollo and GBrowse utilities as well as a wiki, blast search capabilities and a full text search engine. AphidBase strongly supported community cooperation and coordination in the curation of gene models during community annotation of the Pea Aphid genome. AphidBase can be accessed at http://www.Aphidbase.com.
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genome sequence of the Pea Aphid acyrthosiphon pisum
PLOS Biology, 2010Co-Authors: Stephen Richards, Richard A Gibbs, Nicole M Gerardo, Nancy A Moran, Atsushi Nakabachi, David L Stern, Denis Tagu, Alex C C Wilson, Donna M Muzny, Christie L KovarAbstract:Aphids are important agricultural pests and also biological models for studies of insect-plant interactions, symbiosis, virus vectoring, and the developmental causes of extreme phenotypic plasticity. Here we present the 464 Mb draft genome assembly of the Pea Aphid Acyrthosiphon pisum. This first published whole genome sequence of a basal hemimetabolous insect provides an outgroup to the multiple published genomes of holometabolous insects. Pea Aphids are host-plant specialists, they can reproduce both sexually and asexually, and they have coevolved with an obligate bacterial symbiont. Here we highlight findings from whole genome analysis that may be related to these unusual biological features. These findings include discovery of extensive gene duplication in more than 2000 gene families as well as loss of evolutionarily conserved genes. Gene family expansions relative to other published genomes include genes involved in chromatin modification, miRNA synthesis, and sugar transport. Gene losses include genes central to the IMD immune pathway, selenoprotein utilization, purine salvage, and the entire urea cycle. The Pea Aphid genome reveals that only a limited number of genes have been acquired from bacteria; thus the reduced gene count of Buchnera does not reflect gene transfer to the host genome. The inventory of metabolic genes in the Pea Aphid genome suggests that there is extensive metabolite exchange between the Aphid and Buchnera, including sharing of amino acid biosynthesis between the Aphid and Buchnera. The Pea Aphid genome provides a foundation for post-genomic studies of fundamental biological questions and applied agricultural problems.
Yannick Outreman - One of the best experts on this subject based on the ideXlab platform.
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Protective symbiosis: distribution of Hamiltonella defensa in natural populations of Pea Aphid
2020Co-Authors: Mélanie Leclair, Jeanpierre Gauthier, Jeanchristophe Simon, Inès Pons-guillouard, Frédérique Mahéo, Gregory Toussaint, Jean-françois Le Gallic, Yannick OutremanAbstract:Symbiotic associations between microorganisms and eukaryotes are common in nature. These microorganisms can play important role of the evolution and ecology of their hosts by modifying their phenotype like conferring protection against parasitic wasps. This symbiotic protection is encountered in the Pea Aphid, Acyrthosiphon pisum, where the bacterial symbiont Hamiltonella defensa confers protection against parasitoid wasp, Aphidius ervi. Despite this protective benefit, this symbiont occurs only at intermediate frequencies in natural populations. To identify factors influencing the frequency of H. defensa in natural population, we measured Pea Aphid life history traits and the protective effect of this symbiont. We found that protective symbiont doesn’t influence the host life history traits and the protection conferred by this symbiont varies according the biotype of Pea Aphid and the bacterial strain. However, the multiple infections with facultative symbionts reduce the fitness of the host while increasing protection against parasitoids. We also observed the positive correlation between Aphid reproduction in the absence of parasitoid and the level of resistance: higher the symbiotic protection higher the Aphid fecundity. This finding has important implications for the evolution of defensive symbiosis and allows evidence the need for better understanding of how these protective symbionts is maintained in the population.
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Host plant effects on the outcomes of defensive symbioses in the Pea Aphid complex
Evolutionary Ecology, 2019Co-Authors: Corentin Sochard, Jeanchristophe Simon, Mélanie Leclair, Yannick OutremanAbstract:There is increasing evidence that microbial symbionts play pivotal roles in protecting their hosts. Most studies on defensive symbioses have analyzed interaction effects of host-symbiont genotypes on fitness value of defense but very few have considered how local environment could influence symbiont-mediated phenotypes. Our study assessed the effects of environmental variation on the intensity and cost of protection against adverse organisms in lineages of the Pea Aphid, Acyrthosiphon pisum differing by their composition in secondary symbionts. This Aphid is frequently infected by Hamiltonella defensa, singly or in co-infection with Fukatsuia symbiotica, and both bacterial symbionts generally confer a resistance against parasitoids but also induce fitness costs to their hosts. The Pea Aphid forms a complex of plant-adapted biotypes, each specialized on one or a few legume species (i.e., native host). These biotypes can all feed on broad bean, considered as a “universal” host plant. Since plants constitute the primary environment of Aphids in providing both habitat and resources, we tested if symbiont-mediated protection was influenced by whether plant-specialized Aphids fed on their native or universal hosts. For this purpose, parasitism resistance as well as constitutive and induced fitness costs of 21 Pea Aphid lineages differing in biotype and symbiotic complement were measured on both native and universal host plants. We showed that host plant could exert some influence on the outcomes of symbiotic defenses: while the host plant species had very little effect on the protection level against parasitoids, we showed that both costs of symbiotic association and costs induced by parasitism challenge varied in a plant-dependent manner.
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diversity in symbiont consortia in the Pea Aphid complex is associated with large phenotypic variation in the insect host
Evolutionary Ecology, 2016Co-Authors: Jeanchristophe Simon, Mélanie Leclair, Frédérique Mahéo, Ines Pons, Stephanie Morliere, Yannick OutremanAbstract:Virtually all eukaryotes host microbial symbionts that influence their phenotype in many ways. In a host population, individuals may differ in their symbiotic complement in terms of symbiont species and strains. Hence, the combined expression of symbiont and host genotypes may generate a range of phenotypic diversity on which selection can operate and influence host population ecology and evolution. Here, we used the Pea Aphid to examine how the infection with various symbiotic complements contributes to phenotypic diversity of this insect species. The Pea Aphid hosts an obligate symbiont (Buchnera Aphidicola) and several secondary symbionts among which is Hamiltonella defensa. This secondary symbiont confers a protection against parasitoids but can also reduce the host’s longevity and fecundity. These phenotypic effects of H. defensa infection have been described for a small fraction of the Pea Aphid complex which encompasses multiple plant-specialized biotypes. In this study, we examined phenotypic differences in four Pea Aphid biotypes where H. defensa occurs at high frequency and sometimes associated with other secondary symbionts. For each biotype, we measured the fecundity, lifespan and level of parasitoid protection in several Aphid lineages differing in their symbiotic complement. Our results showed little variation in longevity and fecundity among lineages but strong differences in their protection level. These differences in protective levels largely resulted from the strain type of H. defensa and the symbiotic consortium in the host. This study highlights the important role of symbiotic complement in the emergence of phenotypic divergence among host populations of the same species.
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widespread host dependent hybrid unfitness in the Pea Aphid species complex
Evolution, 2014Co-Authors: Jean Peccoud, Joel Bonhomme, Yannick Outreman, Manon De La Huerta, Cindy Laurence, Carole M Smadja, Jeanchristophe SimonAbstract:: Linking adaptive divergence to hybrid unfitness is necessary to understand the ecological factors contributing to reproductive isolation and speciation. To date, this link has been demonstrated in few model systems, most of which encompass ecotypes that occupy relatively early stages in the speciation process. Here we extend these studies by assessing how host-plant adaptation conditions hybrid fitness in the Pea Aphid, Acyrthosiphon pisum. We made crosses between and within five Pea Aphid biotypes adapted to different host plants and representing various stages of divergence within the complex. Performance of F1 hybrids and nonhybrids was assessed on a "universal" host that is favorable to all Pea Aphid biotypes in laboratory conditions. Although hybrids performed equally well as nonhybrids on the universal host, their performance was much lower than nonhybrids on the natural hosts of their parental populations. Hence, hybrids, rather than being intrinsically deficient, are maladapted to their parents' hosts. Interestingly, the impact of this maladaptation was stronger in certain hybrids from crosses involving the most divergent biotype, suggesting that host-dependent postzygotic isolation has continued to evolve late in divergence. Even though host-independent deficiencies are not excluded, hybrid maladaptation to parental hosts supports the hypothesis of ecological speciation in this complex.
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effects of Pea Aphid secondary endosymbionts on Aphid resistance and development of the Aphid parasitoid Aphidius ervi a correlative study
Entomologia Experimentalis Et Applicata, 2010Co-Authors: Franklin N Nyabuga, Jeanchristophe Simon, Yannick Outreman, David G Heckel, Wolfgang W WeisserAbstract:In order to reduce parasite-induced mortality, hosts may be involved in mutualistic interactions in which the partner contributes to resistance against the parasite. The Pea Aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), harbours secondary bacterial endosymbionts, some of which have been reported to confer resistance against Aphid parasitoids. Although this resistance often results in death of the developing parasitoid larvae, some parasitoid individuals succeed in developing into adults. Whether these individuals suffer from fitness reduction compared to parasitoids developing in Pea Aphid clones without symbionts has not been tested so far. Using 30 Pea Aphid clones that differed in their endosymbiont complement, we studied the effects of these endosymbionts on Aphid resistance against the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae), host‐parasitoid physiological interactions, and fitness of emerging adult parasitoids. The number of symbiont species in an Aphid clone was positively correlated with a number of resistance measurements but there were also clear symbiont-specific effects on the host‐parasitoid interaction. As in previous studies, Pea Aphid clones infected with Hamiltonella defensa Moran et al. showed resistance against theparasitoid.Inaddition,PeaAphidclonesinfectedwith Regiella insecticolaMoranet al.and co-infections of H. defensa‐Spiroplasma, R. insecticola‐Spiroplasma ,a ndR. insecticola‐H. defensa showed reduced levels of parasitism and mummification. Parasitoids emerging from symbiontinfected Aphid clones often had a longer developmental time and reduced mass. The number of teratocytes was generally lower when parasitoids oviposited in Aphid clones with a symbiont complement. Interestingly, unparasitized Aphids infected with Serratia symbiotica Moran et al. and R. insecticola had a higher fecundity than unparasitized Aphids of uninfected Pea Aphid clones. We conclude that in addition to conferring resistance, Pea Aphid symbionts also negatively affect parasitoids that successfully hatch from Aphid mummies. Because of the link between Aphid resistance and the number of teratocytes, the mechanism underlying resistance by symbiont infection may involveinterferencewith teratocytedevelopment.