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DGIMI est une unité mixte de recherche ayant pour tutelles INRAE et l'Université de Montpellier. Elle est située sur le campus Triolet de l'Université de Montpellier et accueille une trentaine de personnels INRAE et UM.

Les recherches développées dans l'UMR DGIMI visent à mieux comprendre les interactions entre les insectes et leur environnement biotique et abiotique dans les agrosystèmes, selon deux axes thématiques 

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HAL : Dernières publications

  • [hal-05374380] A characterization of piARNs, their biogenesis and their targets in Spodoptera frugiperda (Lepidoptera, Noctuidae)

    Abstract PIWI-interacting RNAs (piRNAs) and PIWI proteins were initially described as involved in gametogenesis and preservation of genome integrity through the control of transposable elements (TE). Expressed also in the soma and able to regulate protein coding gene expression, they are involved in multiple biological pathways including host-pathogens interaction, sex determination, reproductive isolation. Spodoptera frugiperda is a major invasive insect pest species consisting of two strains with different host-plant ranges. In this paper, we characterized proteins and genomic regions involved in their biogenesis as well as TE and gene transcripts regulated by piRNAs. By phylogenetic analysis, we identified two new Piwi genes conserved in the genus Spodoptera , compared to the Lepidopteran model Bombyx mori , one more than in Drosophila . One of them, more expressed in gonads then soma could be a functional homolog of Drosophila PIWI or replace AGO3. A pool of 11 sRNA-Seq libraries was used to annotate piRNA clusters with Shortstack in the genomes of the two strains of Spodoptera frugiperda . Identification of TE targeted by piRNAs revealed that active transposons differ between the two strains of S. frugiperda despite of a similar TE content, as putative cause or consequence of reproductive isolation. GO analysis of genes targeted by piRNAs shows that some are involved in protein translation initiation. A piRNA cluster in the Masc gene suggests that sex determination is regulated by piRNAs in Spodoptera frugiperda . Our analysis supports that piRNAs have additional roles than silencing of transposable elements and contributes to functional annotation of the two strains genomes of Spodoptera frugiperda .

    ano.nymous@ccsd.cnrs.fr.invalid (Imène Seninet) 20 Nov 2025

    https://hal.inrae.fr/hal-05374380v1
  • [hal-05248666] Global transcriptomics and targeted metabolite analysis reveal the involvement of the AcrAB efflux pump in physiological functions by exporting signaling molecules in Photorhabdus laumondii

    In Gram-negative bacteria, resistance-nodulation-division (RND)-type efflux pumps, particularly AcrAB-TolC, play a critical role in mediating resistance to antimicrobial agents and toxic metabolites, contributing to multidrug resistance. Photorhabdus laumondii is an entomopathogenic bacterium that has garnered significant interest due to its production of bioactive specialized metabolites with anti-inflammatory, antimicrobial, and scavenger deterrent properties. In previous work, we demonstrated that AcrAB confers self-resistance to stilbenes in P. laumondii TT01. Here, we explore the pleiotropic effects of AcrAB in this bacterium. RNA sequencing of ∆acrA compared to wild type revealed growth-phase-specific gene regulation, with stationary-phase cultures showing significant downregulation of genes involved in stilbene, fatty acid, and anthraquinone pigment biosynthesis, as well as genes related to cellular clumping and fimbrial pilin formation. Genes encoding putative LuxR regulators, type VI secretion systems, two-partner secretion systems, and contact-dependent growth inhibition systems were upregulated in ∆acrA. Additionally, exponential-phase cultures revealed reduced expression of genes related to motility in ∆acrA. The observed transcriptional changes were consistent with phenotypic assays, demonstrating that the ∆acrA mutant had altered bioluminescence and defective orange pigmentation due to disrupted anthraquinone production. These findings confirm the role of stilbenes as signaling molecules involved in gene expression, thereby shaping these phenotypes. Furthermore, we showed that AcrAB contributes to swarming and swimming motilities independently of stilbenes. Collectively, these results highlight that disrupting acrAB causes transcriptional and metabolic dysregulation in P. laumondii, likely by impeding the export of key signaling molecules such as stilbenes, which may serve as a ligand for global transcriptional regulators.

    ano.nymous@ccsd.cnrs.fr.invalid (Linda Hadchity) 10 Sep 2025

    https://hal.science/hal-05248666v1
  • [hal-05279475] Pleiotropic role of PAX cyclolipopeptides in the Xenorhabdus bacterium mutualistically associated with entomopathogenic nematodes

    ABSTRACT Xenorhabdus is an entomopathogenic bacterium involved in a mutualistic relationship with Steinernema nematodes. Xenorhabdus produces a multitude of specialized metabolites by non-ribosomal peptide synthetase (NRPS) pathways to mediate bacterium-nematode-insect interactions. PAX cyclolipopeptides are a family of NRP-type molecules whose ecological role remains poorly understood. In this study, the pleiotropic role of PAX peptides in the life cycle of Xenorhabdus nematophila has been investigated. By mass spectrometry analysis, we first demonstrated that PAX peptides were detected from the pathogenic stage up to the necrotrophic stage. We discovered that the bromothymol blue adsorption phenotype historically used to discriminate Xenorhabdus variants was associated with the presence of PAX peptides. We found that PAX peptides were positively involved in biofilm formation and negatively involved in swimming motility. PAX peptides were also shown to promote in vivo the production of infective Steinernema juveniles, suggesting their involvement in the mutualistic relationship between Xenorhabdus and its nematode partner. Finally, we showed that the paxTABC cluster, as well as PAX peptide production, was conserved across the whole Xenorhabdus genus except in Xenorhabdus poinarii and Xenorhabdus ishibashii . This work has revealed multiple new ecological roles for NRP-type peptides. IMPORTANCE Xenorhabdus bacteria are models of particular interest for their mutualistic relationship with Steinernema nematodes and their ability to produce a wide range of natural NRP-type bioactive metabolites. These compounds are mostly studied for their medical or industrial applications, but their ecological role is poorly understood. This study provides a dynamic characterization of PAX cyclolipopeptide presence during the Xenorhabdus nematophila life cycle, as well as confirmation of their production by seven different strains within the Xenorhabdus genus. We revealed new multiple functions for PAX peptides in biofilm formation, swimming motility, and juvenile nematode production. A deeper understanding of how PAX peptides interact with the nematode host would provide a better insight into the role of these cyclolipopeptides in bacterial-nematode mutualism.

    ano.nymous@ccsd.cnrs.fr.invalid (Noémie Claveyroles) 23 Sep 2025

    https://hal.inrae.fr/hal-05279475v1

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article

27 octobre 2025

Rédaction : A-N Volkoff, N. Claveyrolles, N. Nègre, I. Seninet

Notre nouvel article en couverture d’AEM

Les nématodes sont utilisés en lutte biologique pour lutter contre des insectes ravageurs. Pour accomplir leur cycle infectieux, ils sont aidés par leurs bactéries symbiotiques Xenorhabdus qui produit une multitude de métabolites différents. Parmi ces métabolites, Xenorhabdus produit les cyclolipopeptides PAX dont le rôle dans le cycle écologique de la bactérie était peu compris.
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Soutenance de thèse : Shannon Alary

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Bravo à Shannon Alary pour sa soutenance de thèse sur l’effet de la température sur la plasticité des interactions hôte-parasitoïde, encadrée par Isabelle Darboux et Manuel Massot (iEES Paris) !

vignette FDS 2025 DGIMI
04 10

Du 04 oct. 2025 au 05 oct. 2024

Village des sciences de Montpellier

Fête de la science 2025

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Pour cette édition 2025, le laboratoire DGIMI a proposé une animation sur la thématique "Ravageurs malins et microbes futés".

Publication scientifique

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Les populations invasives au Sénégal montrent des traces d’évolution adaptative sur des gènes CYP450 pouvant expliquer leur adaptation au maïs.