Plasmid carriage can limit bacteria-phage coevolution.
Coevolution with bacteriophages is a major selective force shaping bacterial populations and communities. A variety of both environmental and genetic factors has been shown to influence the mode and tempo of bacteria-phage coevolution. Here, we test the effects that carriage of a large conjugative plasmid, pQBR103, had on antagonistic coevolution between the bacterium Pseudomonas fluorescens and its phage, SBW25ϕ2. Plasmid carriage limited bacteria-phage coevolution; bacteria evolved lower phage-resistance and phages evolved lower infectivity in plasmid-carrying compared with plasmid-free populations. These differences were not explained by effects of plasmid carriage on the costs of phage resistance mutations. Surprisingly, in the presence of phages, plasmid carriage resulted in the evolution of high frequencies of mucoid bacterial colonies. Mucoidy can provide weak partial resistance against SBW25ϕ2, which may have limited selection for qualitative resistance mutations in our experiments. Taken together, our results suggest that plasmids can have evolutionary consequences for bacteria that go beyond the direct phenotypic effects of their accessory gene cargo.
Department of Biology, University of York, York YO10 5DD, UK ellie.harrison@york.ac.uk.
Ellie
E
Harrison
Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
Julie
J
Truman
Department of Biology, University of York, York YO10 5DD, UK.
Rosanna
R
Wright
SIMBIOSIS Centre, University of Abertay, Dundee DD1 1HG, UK.
Andrew J
AJ
Spiers
Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
Steve
S
Paterson
Department of Biology, University of York, York YO10 5DD, UK.
Michael A
MA
Brockhurst
D005075:Biological Evolution; D019143:Evolution, Molecular; D009154:Mutation; D010957:Plasmids; D017105:Pseudomonas Phages / Q000235:genetics*; D011551:Pseudomonas fluorescens / Q000235:genetics* / Q000254:growth & development / Q000821:virology
bacteria–phage coevolution; conjugative plasmid; mucoid conversion