Bidirectional incompatibility among divergent Wolbachia and incompatibility level differences among closely related Wolbachia in Nasonia

Abstract

Most insect groups harbor obligate bacterial symbionts from the a-proteobacterial genus Wolbachia. These bacteria alter insect reproduction in ways that enhance their cytoplasmic transmission. One of the most common alterations is cytoplasmic incompatibility (CI) -a post-fertilization modification of the paternal genome that renders embryos inviable or unable to complete diploid development in crosses between infected males and uninfected females or infected females harboring a different strain. The parasitic wasp species complex Nasonia (N. vitripennis, N. longicornis and N. giraulti) harbor at least six different Wolbachia that cause CI. Each species have double infections with a representative from both the A and B Wolbachia subgroups. CI relationships of the A and B Wolbachia of N. longicornis with those of N. giraulti and N. vitripennis are investigated here. We demonstrate that all pairwise crosses between the divergent A strains are bidirectionally incompatible. We were unable to characterize incompatibility between the B Wolbachia, but we establish that the B strain of N. longicornis induces no or very weak CI in comparison to the closely related B strain in N. giraulti that expresses complete CI. Taken together with previous studies, we show that independent acquisition of divergent A Wolbachia has resulted in three mutually incompatible strains, whereas codivergence of B Wolbachia in N. longicornis and N. giraulti is associated with differences in CI level. Understanding the diversity and evolution of new incompatibility strains will contribute to a fuller understanding of Wolbachia invasion dynamics and Wolbachia-assisted speciation in certain groups of insects.

Host genotype changes bidirectional to unidirectional cytoplasmic incompatibility in Nasonia longicornis

“…Repeated efforts to make single B-infected strains failed, probably because of their low titer compared with the wNlonA. This was consistent with previous attempts by Bordenstein and Werren (2007). But fortunately we had access to a single wNlonA-infected strain, (wA) UT4 [UT4] obtained by Bordenstein and Werren (2007) from a double-infected host strain (Supplementary Table S1).…”

“…This was consistent with previous attempts by Bordenstein and Werren (2007). But fortunately we had access to a single wNlonA-infected strain, (wA) UT4 [UT4] obtained by Bordenstein and Werren (2007) from a double-infected host strain (Supplementary Table S1). This strain was used to distinguish the effects of the A supergroup infection in the crosses.…”

Unique clade of alphaproteobacterial endosymbionts induces complete cytoplasmic incompatibility in the coconut beetle

“…Nasonia parasitoid wasps have three sibling species (Nasonia vitripennis, Nasonia longicornis, and Nasonia giraulti) and show bidirectional CI among the species, caused by different strains of Wolbachia (17,18). In this case, Wolbachia may play a causal role in speciation (3,19).…”

The Nuclear Component of a Cytonuclear Hybrid Incompatibility in Mimulus Maps to a Cluster of Pentatricopeptide Repeat Genes

“…Finally, asymmetry in the inheritance of nuclear and cytoplasmic elements may generate the conditions for selfish cytoplasmic evolution and driven nuclear coevolution (Hurst et al 1996;Birky 2001;Burt and Trivers 2006). Maternally inherited endosymbionts that spread by disrupting male function, such as Wolbachia in insects, frequently cause sterility or inviability in interspecific hybrids (Bordenstein et al 2001;Bordenstein and Werren 2007). Similarly, there is an inherent conflict of interest between mitochondrial and nuclear genes that makes their antagonistic coevolution a likely source of hybrid incompatibility, particularly hybrid male sterility (Cosmides and Tooby 1981;Frank 1989;Hurst et al 1996).…”