Portieragives new clues on the evolutionary history of whiteflies

Abstract

Whiteflies (Hemiptera:Sternorrhyncha: Aleyrodidae) are a superfamily of small phloem-feeding insects.Their taxonomy is currently based on the morphology of nymphal stages that display phenotypic plasticity, which produces inconsistencies. To overcome this limitation, we developed a new phylogenetic framework that targets five genes of Candidatus Portiera aleyrodidarum, the primary endosymbiont of whiteflies. Portiera lineages have been co-diverging with whiteflies since their origin and therefore reflect their host evolutionary history. We also studied the origin of stability and instability in Portiera genomes by testing for the presence of two alternative gene rearrangements and the loss of a functional polymerase proofreading subunit (dnaQ), previously associated with genome instability. We present two phylogenetic reconstructions. One using the sequences of all five target genes from 22 whitefly species belonging to 17 genera. The second uses only two genes to include additional published Portiera sequences of 21 whitefly species, increasing our sampling size to 42 species from 25 genera. The developed framework showed low signal saturation, specificity to whitefly samples, and efficiency in solving inter-genera relationships and standing inconsistencies in the current taxonomy of the superfamily. Genome instability was found to be present only in the Aleurolobini tribe containing the Singhiella, Aleurolobus and Bemisia genera. This suggests that Portiera genome instability likely arose in the Aleurolobini tribe's common ancestor, around 70 Mya. We propose a link between the switch from multi-bacteriocyte to a single-bacteriocyte mode of inheritance in the Aleurolobini tribe and the appearance of genome instability in Portiera.

A complex interplay of evolutionary forces continues to shape ancient co-occurring symbiont genomes

“…As a result, there is likely to be tremendous variation among the symbiont genomes of closely related host species. For example, the process of drift is known to cause independent symbiont lineages to differ widely in their genetic capabilities even between closely related host species (McCutcheon and Moran, 2010;Patin ˜o-Navarrete et al, 2013;Husnik et al, 2013;Campbell et al, 2015Campbell et al, , 2017Bennett et al, 2016b;Husnik and McCutcheon, 2016;Boscaro et al, 2017;Łukasik et al, 2018;Chong et al, 2019;Monnin et al, 2020;Santos-Garcia et al, 2020). It is less clear how drift and selection work together to shape and maintain the genes and functions of symbionts as they diversify along with their hosts.…”

Bacterial and fungal communities within and among geographic samples of the hemp pest Psylliodes attenuata from China

“…For example, insect microbiota are known to detoxify noxious secondary metabolites and xenobiotics, such as terpenes (Berasategui et al, 2017), caffeine (Ceja-Navarro et al, 2015;Summers et al, 2015), nicotine (Brandsch, 2006), and insecticides; defending against parasites and other pathogens; generating and relaying signals among hosts; improving behavior and immunity; and producing nutrients to supplement host's diet and to enhance their digestion (Dillon and Dillon, 2004;Ezemwa et al, 2012;Wu et al, 2016). In recent years, a growing number of studies have cataloged and characterized microbial communities, particularly in bees (Moran et al, 2012), fruit flies (Erkosar et al, 2017;Bing et al, 2018), termites (Rossmassler et al, 2015), silkworm (Chen et al, 2018), whiteflies (Santos-Garcia et al, 2020), and beetles (Kudo et al, 2018). For example, Zhang et al (2022) found that a normal gut microbiota is required for olfactory learning and memory abilities, mainly by regulating tryptophan metabolism, with host-specific Lactobacillus strains enhancing memory by transforming tryptophan to indole derivatives that activate the host aryl hydrocarbon receptor in honeybee (Zhang et al, 2022).…”