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Genome Dynamics of Coevolving Podoviruses and Marine Cyanobacteria
Author(s) -
Fenderson Brooke A,
Marston Marcia F
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.474.4
Subject(s) - biology , genome , genetics , gene , synechococcus , virus , coevolution , strain (injury) , host (biology) , bacteriophage , viral evolution , cyanobacteria , bacteria , evolutionary biology , escherichia coli , anatomy
Podoviruses are dsDNA bacteriophage with ~45 kb genomes that are abundant in coastal marine ecosystems. Many of these podoviruses infect cyanobacteria and are thought to undergo antagonistic coevolution with their host. During coevolution, the host evolves resistance to the virus and the viruses evolve to overcome this resistance. Coevolution can impact the fitness and genetic diversity of both host and virus. In this study, whole‐genome sequencing was used to examine the genome dynamics of two closely‐related podoviral strains coevolving with cyanobacteria Synechococcus WH7803 in continuous culture. For each podoviral strain, replicate chemostats containing Synechococcus WH7803 were inoculated with the virus and maintained for 24 weeks. Two additional chemostats of Synechococcus without virus served as the controls. Monthly samples were taken from all chemostats and used to isolate individual viral plaques and Synechococcus colonies. The genomes of viral and host isolates from various time points were then fully sequenced and compared to the genomes of the ancestral strains. Viruses in all four chemostats accumulated mutations as time progressed. These mutations consisted mostly of single nucleotide polymorphisms leading to amino acid changes in the tail fiber region of the viral genome. In addition, large deletions, ranging from 500 to 1600 nt occurred in isolates from later time points in three of the four chemostats. Interestingly, these deletions occurred in regions of the genome that are not shared by the two podoviral strains. In contrast to the viruses, host cells accumulated far fewer mutations and no gene deletions were observed. Only a few mutations were needed for the host to become resistant to the podoviral strains. One of these mutations was located in an intergenic region likely involved in gene regulation and provided broad‐spectrum resistance to both podoviruses and myoviruses. Studying the genome dynamics that occur during coevolution will lead to a better understanding of how viruses and their hosts interact and coexist in natural ecosystems. Support or Funding Information This research was supported by the National Science Foundation (OCE‐0314523, OCE‐1029684 and OIA‐1736030) to M. Marston. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .