Intra-lineage microevolution of < i > Wolbachia < /i > leads to the emergence of new cytoplasmic incompatibility patterns

by Alice Namias, Annais Ngaku, Patrick Makoundou, Sandra Unal, Mathieu Sicard, Myl ène Weill

Mosquitoes of theCulex pipiens complex are worldwide vectors of arbovirus, filarial nematodes, and avian malaria agents. In these hosts, the endosymbiotic bacteriaWolbachia induce cytoplasmic incompatibility (CI), i.e., reduced embryo viability in so-called incompatible crosses.Wolbachia infectingCulex pipiens (wPip) cause CI patterns of unparalleled complexity, associated with the amplification and diversification ofcidA andcidB genes, with up to 6 different gene copies described in a singlewPip genome. InwPip, CI is thought to function as a toxin-antidote (TA) system where compatibility relies on having the right antidotes (CidA) in the female to bind and neutralize the male ’s toxins (CidB). By repeating crosses betweenCulex isofemale lines over a 17 years period, we documented the emergence of a new compatibility type in real time and linked it to a change incid genes genotype. We showed that loss of specificcidA gene copies in somewPip genomes results in a loss of compatibility. More precisely, we found that this lost antidote had an original sequence at its binding interface, corresponding to the original sequence at the toxin ’s binding interface. We showed that these originalcid variants are recombinant, supporting a role for recombination rather than point mutations in rapid CI evolution. These results strongly support the TA model in natura, adding to all previous data...

Source: PLoS Biology: Archived Table of Contents - February 5, 2024 Category: Biology Authors: Alice Namias Source Type: research