Convergent reductive evolution and host adaptation in Mycoavidus bacterial endosymbionts of Mortierellaceae fungi
Year: 2023
Type: article
Abstract: Intimate associations between fungi and intracellular bacterial endosymbionts are becoming increasingly well understood. Phylogenetic analyses demonstrate that bacterial endosymbionts of Mucoromycota fungi are related either to free-living Burkholderia or Mollicutes species. The so-called Burkholderia-related endosymbionts or BRE comprise Mycoavidus, Mycetohabitans and Candidatus Glomeribacter gigasporarum. These endosymbionts are marked by genome contraction thought to be associated with intracellular selection. However, the conclusions drawn thus far are based on a very small subset of endosymbiont genomes, and the mechanisms leading to genome streamlining are not well understood. The purpose of this study was to better understand how intracellular existence shapes Mycoavidus and BRE functionally at the genome level. To this end we generated and analyzed 14 novel draft genomes for Mycoavidus living within the hyphae of Mortierellomycotina fungi. We found that our novel Mycoavidus genomes were significantly reduced compared to free-living Burkholderiales relatives. Using a genome-scale phylogenetic approach including the novel and available existing genomes of Mycoavidus, we show that the genus is an assemblage composed of two independently derived lineages including three well supported clades of Mycoavidus. Using a comparative genomic approach, we shed light on the functional implications of genome reduction, documenting shared and unique gene loss patterns between the three Mycoavidus clades. We found that many endosymbiont isolates demonstrate patterns of vertical transmission and host-specificity, but others are present in phylogenetically disparate hosts. We discuss how reductive evolution and host specificity reflect convergent adaptation to the intrahyphal selective landscape, and commonalities of eukaryotic endosymbiont genome evolution.
Source: Fungal Genetics and Biology
Institutions: Oregon State University, Michigan State University, Lawrence Berkeley National Laboratory, Joint Genome Institute, University of California, Berkeley, Colorado State University, University of Sheffield, University of Exeter, MRC Centre for Medical Mycology, Cornell University, North-West University, New York State College of Agriculture & Life Sciences
Language: English
Subfield: Insect Science
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $2,970
Awards: G1026788151, G1286236842, G1863003419, Investigating microbial predation as a driver of endosymbiosis and phagocyte evasion, BBSRC-NSF/BIO: Investigating microbial predation as a driver of endosymbiosis and phagocyte evasion, G3083819904, Dimensions: Phylogenetic and Functional Diversity of Tripartite Plant-Fungal-Bacterial Symbioses, G419881185, G42916606, G4501827968, G498139845, G5755041744, G6519249983, G7205239661, G7270758689, G834277795, Dimensions US-South Africa: Unravelling the influence of endosymbiotic bacteria on the biodiversity of Mucoromycota fungi, G969889393
OpenAlex ID: W4386782427