title: Genetic diversity of marine Synechococcus and co-occurring cyanophage communities: evidence for viral control of phytoplankton.
abstract: Unicellular cyanobacteria of the genus Synechococcus are a major component of the picophytoplankton and make a substantial contribution to primary productivity in the oceans. Here we provide evidence that supports the hypothesis that virus infection can play an important role in determining the success of different Synechococcus genotypes and hence of seasonal succession. In a study of the oligotrophic Gulf of Aqaba, Red Sea, we show a succession of Synechococcus genotypes over an annual cycle. There were large changes in the genetic diversity of Synechococcus, as determined by restriction fragment length polymorphism analysis of a 403- bp rpoC1 gene fragment, which was reduced to one dominant genotype in July. The abundance of co-occurring cyanophage capable of infecting marine Synechococcus was determined by plaque assays and their genetic diversity was determined by denaturing gradient gel electrophoresis analysis of a 118-bp g20 gene fragment. The results indicate that both abundance and genetic diversity of cyanophage covaried with that of Synechococcus. Multivariate statistical analyses show a significant relationship between cyanophage assemblage structure and that of Synechococcus. These observations are consistent with cyanophage infection being a major controlling factor in picophytoplankton succession.
authors.affiliation: Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH, UK. mmuh@mail.pml.ac.uk
authors.forename: Martin
authors.initials: M
authors.lastname: Mühling
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Fuller
authors.forename: Andrew
authors.initials: A
authors.lastname: Millard
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Somerfield
authors.forename: Dominique
authors.initials: D
authors.lastname: Marie
authors.forename: William H
authors.initials: WH
authors.lastname: Wilson
authors.forename: David J
authors.initials: DJ
authors.lastname: Scanlan
authors.forename: Anton F
authors.initials: AF
authors.lastname: Post
authors.forename: Ian
authors.initials: I
authors.lastname: Joint
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Mann
mesh_terms: D001435:Bacteriophages / Q000235:genetics* / Q000254:growth & development; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D004279:DNA, Viral / Q000032:analysis / Q000302:isolation & purification; D005798:Genes, Bacterial; D014644:Genetic Variation; D019156:Indian Ocean; D008969:Molecular Sequence Data; D010802:Phylogeny; D010839:Phytoplankton / Q000254:growth & development* / Q000821:virology; D012150:Polymorphism, Restriction Fragment Length; D012320:RNA Polymerase III / Q000235:genetics; D012623:Seawater / Q000382:microbiology* / Q000821:virology*; D017422:Sequence Analysis, DNA; D046940:Synechococcus / Q000235:genetics* / Q000254:growth & development / Q000821:virology*; D010948:Viral Plaque Assay; D014871:Water Microbiology
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral; D012320:RNA Polymerase III