title: Elucidating the Diversity of Aquatic Microdochium and Trichoderma Species and Their Activity against the Fish Pathogen Saprolegnia diclina.
abstract: Animals and plants are increasingly threatened by emerging fungal and oomycete diseases. Amongst oomycetes, Saprolegnia species cause population declines in aquatic animals, especially fish and amphibians, resulting in significant perturbation in biodiversity, ecological balance and food security. Due to the prohibition of several chemical control agents, novel sustainable measures are required to control Saprolegnia infections in aquaculture. Previously, fungal community analysis by terminal restriction fragment length polymorphism (T-RFLP) revealed that the Ascomycota, specifically the genus Microdochium, was an abundant fungal phylum associated with salmon eggs from a commercial fish farm. Here, phylogenetic analyses showed that most fungal isolates obtained from salmon eggs were closely related to Microdochium lycopodinum/Microdochium phragmitis and Trichoderma viride species. Phylogenetic and quantitative PCR analyses showed both a quantitative and qualitative difference in Trichoderma population between diseased and healthy salmon eggs, which was not the case for the Microdochium population. In vitro antagonistic activity of the fungi against Saprolegnia diclina was isolate-dependent; for most Trichoderma isolates, the typical mycoparasitic coiling around and/or formation of papilla-like structures on S. diclina hyphae were observed. These results suggest that among the fungal community associated with salmon eggs, Trichoderma species may play a role in Saprolegnia suppression in aquaculture.
authors.affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen 6708 PB, The Netherlands. y.liu@nioo.knaw.nl.|Laboratory of Phytopathology, Wageningen University, Wageningen 6708 PB, The Netherlands. y.liu@nioo.knaw.nl.
authors.forename: Yiying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Austrian Centre of Industrial Biotechnology (ACIB GmbH), Graz 8010, Austria. christin.zachow@acib.at.
authors.forename: Christin
authors.initials: C
authors.lastname: Zachow
authors.affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen 6708 PB, The Netherlands. j.raaijmakers@nioo.knaw.nl.|Institute of Biology, Leiden University, Leiden 2333 BE, The Netherlands. j.raaijmakers@nioo.knaw.nl.
authors.forename: Jos M
authors.initials: JM
authors.lastname: Raaijmakers
authors.affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen 6708 PB, The Netherlands. i.debruijn@nioo.knaw.nl.
authors.forename: Irene
authors.initials: I
authors.lastname: de Bruijn
mesh_terms: D000818:Animals; D000898:Antibiosis; D017756:Aquaculture; D044822:Biodiversity; D061046:Biological Control Agents; D005393:Fish Diseases / Q000469:parasitology / Q000628:therapy*; D007239:Infections / Q000469:parasitology / Q000628:therapy*; D010802:Phylogeny; D012474:Salmon / Q000382:microbiology / Q000469:parasitology; D044762:Saprolegnia / Q000254:growth & development / Q000382:microbiology* / Q000472:pathogenicity; D013149:Spiroplasma / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D014242:Trichoderma / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D015053:Zygote / Q000382:microbiology / Q000469:parasitology
chemical_list: D061046:Biological Control Agents
keywords: Microdochium; Saprolegniosis; Trichoderma; salmon