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DGIMI - Diversity, Genomes and Insects-Microorganisms Interactions

DGIMI is a joint research unit supervised by INRAE and the University of Montpellier. It is located on the Triolet campus of the University of Montpellier, and houses staff from both INRAE and UM.

The research carried out by UMR DGIMI is devoted to the study of interaction mechanisms between insect crop pests, their pathogens and parasites, and their host plants. This research takes into account the diversity of the partners and is based on knowledge of their genomes.

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HAL : Dernières publications

  • [hal-05027917] Divergent Selection Promotes Intraspecific Genomic Differentiation in Spodoptera littoralis With Possible Involvement in Detoxification

    The cotton leafworm, Spodoptera littoralis (Lepidoptera: Noctuidae), is a major agricultural pest affecting crops like cotton, maize, tomatoes, and wheat across southern Europe, Africa, the Middle East, and western Asia. Whole genome analyses have revealed adaptive evolution in chemosensation and detoxification genes in S. littoralis. However, the extent of intraspecific diversity influenced by recent adaptive evolutionary forces remains unclear. In this study, we conducted a population genomics analysis using 31 S. littoralis individuals from sub-Saharan Africa, northern Africa, and southern Europe to assess the existence of intraspecific population divergence and identify the underlying evolutionary forces. We show whole genome differentiation between populations based on geographic origin from the analyzed samples. Phylogenetic analyses indicate that sub-Saharan and southern European populations share a common ancestor, distinct from several northern African populations. FST and dXY statistics along the chromosomes reveal loci with restricted gene flow among populations. These loci are associated with population-specific selective sweeps, indicating the role of divergent natural selection in limiting gene flow. Notably, these loci are enriched with detoxification genes, including cytochrome P450, multidrug resistance, and xanthine dehydrogenase genes, all of which are potentially associated with detoxification. These results demonstrate that divergent selection limits gene flow among geographically distinct populations with the possibility of the involvement of detoxification as a key trait. We argue that this genetic heterogeneity can be considered in pest monitoring and management, as strategies tailored to specific populations may not be relevant for others.

    ano.nymous@ccsd.cnrs.fr.invalid (Karine Durand) 09 Apr 2025

    https://hal.inrae.fr/hal-05027917v1
  • [hal-05039973] Towards identification of a holocentromere marker in the lepidopteran model <i>Spodoptera frugiperda</i>

    &lt;div&gt;&lt;p&gt;Some insects have holocentric chromosomes, with multiple kinetochores rather than a single centromere. They also lack the CENP-A and CENP-C proteins, suggesting a kinetochore assembly process different from that of monocentric chromosomes. The homolog of CENP-T was recently shown to bind silent chromatin and to play a key role in kinetochore assembly in Bombyx mori, but its role in other insects with holocentric chromosomes is unknown. We identified kinetochore genes and analyzed their expression in Spodoptera frugiperda. We silenced the kinetochore genes cenp-L, cenp-S, cenp-X and ndc80 and searched for chromosome segregation defects in Sf9 cells. All kinetochore genes except cenp-S were more strongly expressed in gonadal than in somatic tissues. Immunofluorescence microscopy and RT-qPCR demonstrated the effective silencing of the target genes by transfection with dsRNA. In Sf9 cells depleted of CENP-L and NDC80, immunofluorescence microscopy revealed increases in mitotic index and in the proportion of cells with unaligned chromosomes or multipolar spindles. The depletion of CENP-S and CENP-X had no effect on mitotic index and no division defects were observed. This suggests that CENP-L and NDC80 play key roles in chromosome segregation, whereas the functions of CENP-S and CENP-X remain unknown. We have begun to characterize the kinetochore proteins (CENP-L, CENP-S, CENP-X, NDC80), a prerequisite for holocentromere identification in S. frugiperda. This study also provides the first information about the role, in Lepidoptera, of CENP-L, a protein essential to the structure of the constitutive centromere-associated network in species with monocentric chromosomes.&lt;/p&gt;&lt;/div&gt; &lt;div&gt;Keywords&lt;p&gt;Kinetochore • Holocentric chromosome • Centromere • RNAi • Chromosome segregation • Lepidoptera * Emmanuelle d'Alençon&lt;/p&gt;&lt;/div&gt;

    ano.nymous@ccsd.cnrs.fr.invalid (Sylvie Gimenez) 18 Apr 2025

    https://hal.inrae.fr/hal-05039973v1
  • [hal-04941032] A fi rst characterization of kinetochore proteins in theholocentric insect Spodoptera frugiperda

    Abstract Insects with holocentric chromosomes have a centromere spread all over their length and are devoid of the proteins CENP-A and CENP-C, suggesting a different kinetochore assembly process compared to that in monocentrics. Very recently, the homolog of CENP-T was shown to play a key role in kinetochore assembly in Bombyx mori and to bind to silent chromatin regions. However, nothing is known in other holocentric insects. In this paper, we set up a protocol to silence the kinetochore genes cenp -L, cenp -S, cenp -X and ndc 80 and searched for chromosome segregation defects in Spodoptera frugiperda cells. We also analyzed their expression pattern in the insect. As shown by immunofluorescence microscopy and RT-QPCR, we succeeded to silence target genes efficiently by transfection with dsRNA. In Sf9 cells depleted for CENP-L and NDC80, by immunofluorescence microscopy, we observed an increase of mitotic indices linked to metaphase arrest and, respectively unaligned chromosomes and multipolar spindles. In cells depleted for CENP-S and CENP-X, the mitotic indices were unchanged and no division defects were observed. Except cenp -S and X, kinetochore genes were overexpressed in gonadal versus somatic tissues. We conclude that CENP-L and NDC80 play a major role in chromosome segregation, while the function of CENP-S and -X are still unknown. We started to characterize the kinetochore proteins (CENP-L, CENP-S, CENP-X, NDC80), a prerequisite for holocentromere identification in S. frugiperda . We provide the first clues on CENP-L in Lepidoptera, a protein playing a central role in the structure of the Constitutive Centromere Associated Network in monocentrics

    ano.nymous@ccsd.cnrs.fr.invalid (Emmanuelle d'Alençon) 11 Feb 2025

    https://hal.inrae.fr/hal-04941032v1

News

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article

06 March 2025

By: A-N Volkoff, N. Nègre , I. Seninet

A new scientific publication

Invasive populations in Senegal show evidence of adaptive evolution on CYP450 genes that may explain their adaptation to maize
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photo Peter Heeling

Website under restructuring

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Our website is currently being restructured.

Postdoctoral Position in CRISPR/Cas9 Gene Editing in Insects (University of Montpellier)

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Location: UMR-DGIMI, University of Montpellier, France / Duration: 18 months / Start Date: Preferably from April 2025