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Diversity and evolutionary relationships of T 7‐like podoviruses infecting marine cyanobacteria
Author(s) -
DekelBird Naama P.,
Avrani Sarit,
Sabehi Gazalah,
Pekarsky Irina,
Marston Marcia F.,
Kirzner Shay,
Lindell Debbie
Publication year - 2013
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12103
Subject(s) - biology , clade , phylogenetic tree , prochlorococcus , phylogenetics , gene , evolutionary biology , genetics , genetic diversity , synechococcus , host (biology) , population , cyanobacteria , bacteria , demography , sociology
Summary Phages are extremely abundant in the oceans, influencing the population dynamics, diversity and evolution of their hosts. Here we assessed the diversity and phylogenetic relationships among T 7‐like cyanophages using DNA polymerase (replication), major capsid (structural) and photosynthesis psbA (host‐derived) genes from isolated phages. DNA polymerase and major capsid phylogeny divided them into two discrete clades with no evidence for gene exchange between clades. Clade A phages primarily infect S ynechococcus while clade B phages infect either S ynechococcus or P rochlorococcus . The major capsid gene of one of the phages from clade B carries a putative intron. Nearly all clade B phages encode psbA whereas clade A phages do not. This suggests an ancient separation between cyanophages from these two clades, with the acquisition or loss of psbA occurring around the time of their divergence. A mix and match of clustering patterns was found for the replication and structural genes within each major clade, even among phages infecting different host genera. This is suggestive of numerous gene exchanges within each major clade and indicates that core phage functions have not coevolved with specific hosts. In contrast, clustering of phage psbA broadly tracks that of the host genus. These findings suggest that T 7‐like cyanophages evolve through clade‐limited gene exchanges and that different genes are subjected to vastly different selection pressures.