Open AccessIdentification of Freshwater Phycodnaviridae and Their Potential Phytoplankton Hosts, Using DNA pol Sequence Fragments and a Genetic-Distance Analysis
Author(s) -
Jessica L. Clasen,
Curtis A. Suttle
Publication year - 2009
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.02024-08
Subject(s) - biology , phylogenetic tree , phytoplankton , monophyly , host (biology) , environmental dna , dna sequencing , phylogenetics , zoology , ecology , dna , gene , genetics , biodiversity , clade , nutrient
Viruses that infect phytoplankton are an important component of aquatic ecosystems, yet in lakes they remain largely unstudied. In order to investigate viruses (Phycodnaviridae ) infecting eukaryotic phytoplankton in lakes and to estimate the number of potential host species, samples were collected from four lakes at the Experimental Lakes Area in Ontario, Canada, during the ice-free period (mid-May to mid-October) of 2004. From each lake,Phycodnaviridae DNA polymerase (pol ) gene fragments were amplified using algal-virus-specific primers and separated by denaturing gradient gel electrophoresis; 20 bands were extracted from the gels and sequenced. Phylogenetic analysis indicated that freshwater environmental phycodnavirus sequences belong to distinct phylogenetic groups. An analysis of the genetic distances “within” and “between” monophyletic groups of phycodnavirus isolates indicated that DNApol sequences that differed by more than 7% at the inferred amino acid level were from viruses that infect different host species. Application of this threshold to phylogenies of environmental sequences indicated that the DNApol sequences from these lakes came from viruses that infect at least nine different phytoplankton species. A multivariate statistical analysis suggested that potential freshwater hosts includedMallomonas sp.,Monoraphidium sp., andCyclotella sp. This approach should help to unravel the relationships between viruses in the environment and the phytoplankton hosts they infect.