Origin and Examination of a Leafhopper Facultative Endosymbiont

Abstract

Eukaryotes engage in intimate interactions with microbes that range in age and type of association. Although many conspicuous examples of ancient insect associates are studied (e.g., Buchneraaphidicola), fewer examples of younger associations are known. Here, we further characterize a recently evolved bacterial endosymbiont of the leafhopper Euscelidius variegatus (Hemiptera, Cicadellidae), called BEV. We found that BEV, continuously maintained in E. variegatus hosts at UC Berkeley since 1984, is vertically transmitted with high fidelity. Unlike many vertically transmitted, ancient endosymbioses, the BEV–E. variegatus association is not obligate for either partner, and BEV can be cultivated axenically. Sufficient BEV colonies were grown and harvested to estimate its genome size and provide a partial survey of the genome sequence. The BEV chromosome is about 3.8 Mbp, and there is evidence for an extrachromosomal element roughly 53 kb in size (e.g., prophage or plasmid). We sequenced 438 kb of unique short-insert clones, representing about 12% of the BEV genome. Nearly half of the gene fragments were similar to mobile DNA, including 15 distinct types of insertion sequences (IS). Analyses revealed that BEV not only shares virulence genes with plant pathogens, but also is closely related to the plant pathogenic genera Dickeya, Pectobacterium, and Brenneria. However, the slightly reduced genome size, abundance of mobile DNA, fastidious growth in culture, and efficient vertical transmission suggest that symbiosis with E. variegatus has had a significant impact on genome evolution in BEV.Electronic supplementary materialThe online version of this article (doi:10.1007/s00284-011-9893-5) contains supplementary material, which is available to authorized users.

Similar sponge‐associated bacteria can be acquired via both vertical and horizontal transmission

“…Bacteria that are both vertically and horizontally transmitted exist in insects. They are considered to be facultative symbionts and explain the incongruent evolutionary history of host and bacterial symbionts (Degnan et al ., ; Gonella et al ., ). A similar incongruence of host and bacteria phylogeny has been observed for sponges and their associated bacteria (Erpenbeck et al ., ; Schmitt et al ., ), which led to the hypothesis of a model of mixed vertical and horizontal transmission of bacteria in sponges (Schmitt et al ., ) and highlight the importance of both sponge host‐specific and environment specific factors (Erwin et al ., ).…”

A 454 Survey Reveals the Community Composition and Core Microbiome of the Common Bed Bug (Cimex lectularius) across an Urban Landscape

“…Phylogenetic assessment of this taxon found it to exhibit greater than 99% similarity to BEV [29], a facultative endosymbiont reported from the leafhopper Euscelidius variegatus [48] and closely related to the plant pathogenic genera Dickeya , Pectobacterium , and Erwinia [49]. Close phylogenetic relationships between endosymbionts found in plant-feeding and blood-feeding insect hosts have been uncovered in other bacterial clades- Rickettsia , Sodalis and Arsenophonus [50], [51], [52]- and may represent putative examples of horizontal transfer, potentially due to their ability to persist outside of hosts [49]. While the phenotypic effects of this γ-proteobacteria on C. lectularius are largely unknown, there are accounts of pen-strep treatment (which does not affect Wolbachia ) leading to reductions in egg production in C. lectularius , suggesting that the removal of the γ-proteobacteria can lead to reductions in fertility [41] and thus it may prove to be a nutritional mutualist as well.…”

Diversity of Bacterial Endosymbionts Associated with Macrosteles Leafhoppers Vectoring Phytopathogenic Phytoplasmas

“…Sulcia muelleri" coexists with a different endosymbiont, "Candidatus Nasuia deltocephalinicola," within the same bacteriomes (13,14). In addition to these bacteriome-associated endosymbionts of obligate nature, various endosymbionts of facultative nature, such as Wolbachia (11,(15)(16)(17), Rickettsia (13,18), Spiroplasma (19,20), Cardinium (21,22), and others (23,24), have been sporadically recorded from some leafhoppers, although these surveys are not systematic but rather fragmentary, giving no coherent picture of endosymbiotic microbiota in specific leafhopper species and populations.…”