Genomic islands in Wolbachia prophages drive amplification and diversification of cytoplasmic incompatibility genes in Culex pipiens
5 affiliations
- 1ISEM, Université de Montpellier, CNRS, IRD , Montpellier 34095 ,
- 2MIVEGEC, Université de Montpellier, CNRS, IRD , Montpellier 34394 ,
- 3Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Société Evolution , Gif-sur-Yvette 91190 ,
- 4ASTRE, Université de Montpellier, INRAe, CIRAD , Montpellier 34398 ,
- 5Tree of Life, Wellcome Sanger Institute , Hinxton, Cambridge CB10 1SA ,
Abstract
Wolbachia are maternally inherited endosymbiotic bacteria widespread among arthropods. They manipulate their host reproduction to enhance their prevalence in host populations. The most common manipulation is cytoplasmic incompatibility (CI), which causes embryonic death in crosses between infected males and uninfected females, or between individuals carrying incompatible Wolbachia strains. CI patterns are highly complex in the mosquito Culex pipiens, where the causal genes cidA and cidB are amplified and diversified, forming a "cid repertoire" within each Wolbachia wPip genome. Despite their central role in CI, the genomic mechanisms underlying such cid amplification and diversification remain poorly understood. This knowledge gap is largely due to the difficulty of assembling wPip's genomes due to highly repeated genes and mobile elements, especially in WO prophages. Here, we directly annotated Illumina-corrected Nanopore sequences to investigate the genomic flanking context of cid genes in 3 distinct wPip lineages. We assembled WO prophage regions of substantial length containing the entire cid repertoire previously described in these bacterial lineages. Within these WO regions, cid genes are consistently embedded in modular and rearrangeable islands composed of MutL, rnhA, and small mobile elements, all displaying hyperconserved nucleotide identity across islands. These genomic islands are probably drivers for major rearrangement and recombination events responsible for the amplification and diversification of cidwPip genes within and between the wPip genomes, leading to CI complexity in C. pipiens.
Related
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- Extensive mobilome heterogeneity in a widespread endosymbiont: A candidate dimeric plasmid and highly fragmented prophages in Wolbachia from Culex pipiens
- Type III CI factors from wAlbB induce cytoplasmic incompatibility via a Host Modification mechanism
- Relatedness of Gardnerella prophages and their endolysins
- Editorial: New Frontiers in Wolbachia biology 2025
BibTeX
@article{amoros2026genomic,
title = {{Genomic islands in Wolbachia prophages drive amplification and diversification of cytoplasmic incompatibility genes in Culex pipiens}},
author = {Julien Amoros and Alice Namias and Theo Durand and Haoués Alout and Julien Martinez and Mylène Weill and Mathieu Sicard},
journal = {Genetics},
year = {2026},
month = may,
doi = {10.1093/genetics/iyag135},
url = {https://doi.org/10.1093/genetics/iyag135},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Genomic islands in Wolbachia prophages drive amplification and diversification of cytoplasmic incompatibility genes in Culex pipiens
AU - Julien Amoros
AU - Alice Namias
AU - Theo Durand
AU - Haoués Alout
AU - Julien Martinez
AU - Mylène Weill
AU - Mathieu Sicard
PY - 2026
DA - 2026/05/22
JO - Genetics
DO - 10.1093/genetics/iyag135
UR - https://doi.org/10.1093/genetics/iyag135
AB - Wolbachia are maternally inherited endosymbiotic bacteria widespread among arthropods. They manipulate their host reproduction to enhance their prevalence in host populations. The most common manipulation is cytoplasmic incompatibility (CI), which causes embryonic death in crosses between infected males and uninfected females, or between individuals carrying incompatible Wolbachia strains. CI patterns are highly complex in the mosquito Culex pipiens, where the causal genes cidA and cidB are amplified and diversified, forming a "cid repertoire" within each Wolbachia wPip genome. Despite their central role in CI, the genomic mechanisms underlying such cid amplification and diversification remain poorly understood. This knowledge gap is largely due to the difficulty of assembling wPip's genomes due to highly repeated genes and mobile elements, especially in WO prophages. Here, we directly annotated Illumina-corrected Nanopore sequences to investigate the genomic flanking context of cid genes in 3 distinct wPip lineages. We assembled WO prophage regions of substantial length containing the entire cid repertoire previously described in these bacterial lineages. Within these WO regions, cid genes are consistently embedded in modular and rearrangeable islands composed of MutL, rnhA, and small mobile elements, all displaying hyperconserved nucleotide identity across islands. These genomic islands are probably drivers for major rearrangement and recombination events responsible for the amplification and diversification of cidwPip genes within and between the wPip genomes, leading to CI complexity in C. pipiens.
SN - 0016-6731
SN - 1943-2631
ER -