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Saprolegnia molecular phylogeny among farmed teleosts in Nova Scotia, Canada
Author(s) -
Sarowar Mohammad Nasif,
Cusack Roland,
Duston James
Publication year - 2019
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/jfd.13090
Subject(s) - saprolegnia , biology , salmo , brown trout , salvelinus , phylogenetic tree , zoology , oomycete , trout , nova scotia , botany , fishery , microbiology and biotechnology , fish <actinopterygii> , genetics , gene , history , archaeology , pathogen
To identify the pathogens causing saprolegniosis among farmed fish in Nova Scotia, 172 infected tissues and 23 water samples were collected from six species of teleosts: Atlantic salmon ( Salmo salar ), brown trout ( Salmo trutta ), Arctic charr ( Salvelinus alpinus ), brook trout ( Salvelinus fontinalis ), striped bass ( Morone saxatilis ) and rainbow trout ( Oncorhynchus mykiss ) at nine facilities over a 600 km range. Following laboratory culture, 132 isolates were recovered. Six species of oomycetes were identified from analysis of the internal transcribed spacer (ITS) sequence of the nrDNA: Saprolegnia parasitica , Saprolegnia ferax , Saprolegnia diclina , Saprolegnia aenigmatica , Saprolegnia torulosa , Saprolegnia sp. and Pythiopsis cymosa . Further phylogenetic analyses of the ITS and cytochrome c oxidase subunit 1 ( Cox1 ) regions revealed four strains of Saprolegnia parasitica (named here as S1, S2, S3 and S4), of which S1 and S2 were common (37% and 42% of the isolates), and two strains of S. ferax . Among S. parasitica , S2 and S3 are more closely related to each other than to S1 based on the phylogenetic analyses and predicted RNA secondary structure of the ITS region. Sexual structures with a similar morphology were formed by S1 and S3 in vitro , but were not formed by S2.