Reduced and Nonreduced Genomes in Paraburkholderia Symbionts of Social Amoebas

Abstract

Protists are a diverse group of typically single cell eukaryotes. Bacteria and archaea that form long-term symbiotic relationships with protists may evolve in additional ways than those in relationships with multicellular eukaryotes such as plants, animals, or fungi.

Facultative symbiont virulence determines horizontal transmission rate without host strain specificity

“…P. bonniea , along with P. hayleyella and P. agricolaris , is able to persistently infect D. discoideum and form a facultative symbiosis (DiSalvo et al 2015; Haselkorn et al 2019; Miller et al 2020). Both P. bonniea and P. hayleyella have reduced genomes that are roughly half the size of P. agricolaris , leading to the hypothesis that both reduced-genome species may have associated with D. discoideum for a longer period of evolutionary time compared to P. agricolaris (Brock et al 2020; Noh et al 2022), and thus forming a stable facultative symbiosis. Whereas we had expected that the presence of reduced-genome symbionts may likely be due to host-symbiont coevolution, our results indicate this may not be the case for hosts and P. bonniea symbionts.…”

“…All three species of D. discoideum -associated Paraburkholderia are unique among close relatives in their ability to persistently infect D. discoideum (DiSalvo et al 2015; Haselkorn et al 2019). But two of the Paraburkholderia symbionts have genomes that are half the size of the third (Brock et al 2020; Noh et al 2022). Longer term symbionts tend to have smaller genomes compared to free-living relatives (Mira et al 2001; Weinert and Welch 2017).…”

“…Longer term symbionts tend to have smaller genomes compared to free-living relatives (Mira et al 2001; Weinert and Welch 2017). While P. agricolaris is difficult to distinguish from other Paraburkholderia species based on its genome size and content, comparative genomics analyses indicate that P. bonniea and P. hayleyella have evolved reduced genomes in the amoeba host environment (Noh et al 2022).…”

Complex third-party effects in theDictyostelium-Paraburkholderiasymbiosis: prey bacteria that are eaten, carried, or left behind

“…One species of symbiont, P. hayleyella, appears to have led to host adaptation in response to the presence of symbionts (Shu et al, 2018a). P. hayleyella and P. bonniae also have reduced genomes relative to P. agricolaris and most other Paraburkholderia (Brock et al, 2020;Noh et al, 2022), which indicates that P. hayleyella and P. bonniea have been associated closely with their hosts during a long evolutionary history (McCutcheon & Moran, 2012). Fitness of D. discoideum hosts and Paraburkholderia symbionts is affected by interactions with a third set of organisms, the various food bacteria in the environment that are eaten by host amoebae (Brock et al, 2011;DiSalvo et al, 2015;Scott et al, 2022).…”

“…One species of symbiont, P. hayleyella ,appears to have led to host adaptation in response to the presence of symbionts (Shu et al ., 2018a). P. hayleyella and P. bonniae also have reduced genomes relative to P. agricolaris and most other Paraburkholderia (Brock et al ., 2020; Noh et al ., 2022), which indicates that P. hayleyella and P. bonniea have been associated closely with their hosts during a long evolutionary history (McCutcheon & Moran, 2012).…”