Large-scale comparative genomics unravels great genomic diversity across the Rickettsia and Ca. Megaira genera and identifies Torix group as an evolutionarily distinct clade

• DOI: 10.1101/2021.10.06.463315
• Publication Date: 2021-10-07T02:52:12Z
• Authors: Helen R Davison; Jack Pilgrim; Nicky Wybouw; Joseph Parker; Stacy Pirro; Simon Hunter-Barnett; Paul M Campbell; Frances Blow; Alistair C Darby; Gregory D D Hurst; Stefanos Siozios
• Keywords: Candidatus; Buchnera; Comparative Genomics

Abstract Rickettsia are intracellular bacteria originally described as arthropod borne pathogens that emerging a diverse group of often biologically important, non-pathogenic symbionts invertebrates and microeukaryotes. However, sparse genomic resources for symbiotic strains the sister genus ( Candidatus Megaira) inhibit our understanding evolution biology. Here, we present first closed genomes Ca . Megaira from an alga Mesostigma viride ), Torix midge Culicoides impunctatus ) bed bug Cimex lectularius hosts. Additionally, sequenced constructed draft another Carteria cerasiformis Transitional tsetse fly Glossina morsitans submorsitans spider mite Bryobia graminum ). We further extract 22 genome sequencing projects, including 1 Adalia, 4 Transitional, Spotted Fever, 7 Torix, Belli Rhyzobius Meloidae genomes. used new existing to estimate phylogeny metabolic potential across groups reveal transitions in properties. These data unique amongst currently , with highly distinct accessory confirm presence third subclade previously only known gene marker sequences. Further, share intact pentose phosphate pathway Megaira, not observed other Considering distinctness diversity propose be named Tisiphia. The wide host range Tisiphia necessitates onward research understand biological physiological bases Tisiphia-host interactions. Importance statement Members were identified causative agents mammalian vector-borne disease. In last 25 years have recognised many symbionts, sit alongside taxon, which associates lack information affects ability determine evolutionary relationships between underpinnings different symbioses. clarify these by assembling 26 understudied groups, two various insects Of note, broad parallels all combined. This diversity, breadth species, make clade important hidden player invertebrate biology physiology. argue this should given its own status,