Characterization of Achlya americana and A. bisexualis (Saprolegniales, Oomycota) Isolated from Freshwater Environments in Korea

Abstract

Many members of the Saprolegniales (Oomycete) cause mycoses and disorders of fishes, of which Achlya and Saprolegnia are most ubiquitous genera worldwide. During a survey of the diversity of freshwater oomycetes in Korea, we collected seven isolates of Achlya , for which morphological and molecular phylogenetic analyses enabled them to identify as Achlya americana and Achlya bisexualis . In Korea, only a species of Achlya , A. prolifera , has been previously found to cause seedling rot on rice ( Oryza sativa ), but none of the two species have been reported yet. Importantly, A. bisexualis was isolated from a live fish, namely rice fish ( Oryzias sinensis ), as well as freshwater, and this is the first report of Achlya -causing mycoses on freshwater fishes in Korea. The presence of A. americana and A. bisexualis on live fish in Korea should be closely monitored, as considering the well-known broad infectivity of these species it has the potential to cause an important emerging disease on aquaculture industry.

Veronaea aquatica sp. nov. (Herpotrichiellaceae, Chaetothyriales, Eurotiomycetes) from submerged bamboo in China

“…They are "recyclers" in that they decompose dead organic matter (Harms et al 2011, Iskandar et al 2011, Anastasi et al 2013, Tsui et al 2016, Grossart et al 2019, Gulis et al 2019. Freshwater fungi can be found in living (plants and animals) and non-living (decaying wood and leaves) substrates (Choi et al 2019, Grossart et al 2019, Tsui et al 2000. They are accommodated in eight phyla: Aphelidiomycota, Ascomycota, Basidiomycota, Blastocladiomycota, Chytridiomycota, Monoblepharomycota, Mortierellomycota and Rozellomycota (Zhang et al 2012, Bao et al 2019, Calabon et al 2020, Hyde et al 2021).…”

PhytopythiumandPythiumSpecies (Oomycota) Isolated from Freshwater Environments of Korea

“…Oomycota, a monophyletic group of filamentous microbes under the kingdom Straminipila, is ubiquitous in the oceans [1,2], freshwater [3,4], and terrestrial environments [5,6] throughout the world. Aquatic oomycetes are often referred to as “water molds” and play significant roles on aquatic ecosystems, where most oomycetes are saprotrophic, responsible for decomposing and recycling of organic materials.…”

“…Nevertheless, the traits of aquatic oomycetes regard to saprophytism and endophytism are largely unknown, in comparison with the parasitic species that infect fish, fish eggs [9,10], and algae [11,12]. In Korea, aquatic oomycetes relating to fish and algae diseases have been recently recorded, e.g., Achlya [3], Pythium [12,13], and Saprolegnia [14]. However, diversity of saprotrophic or endophytic oomycetes in Korea remains still poorly understood.…”

Efficacy of acriflavin chloride and Melaleuca alternifolia extract against Saprolegnia parasitica infection in Pterophyllum scalare

“…Oomycetes are a diverse group of filamentous eukaryotic microbiota that includes animal and plant pathogens (Gaulin et al, 2010). Many representatives of Saprolegniales (Oomycetes) cause fungal diseases of fish, among which the most common genera are Achlya and Saprolegnia (Kar, 2016;Wuensch et al, 2018;Choi et al, 2019). Oomycetes are divided into three subclasses: Saprolegniomycetidae, Rhipidiomycetidae and Peronosporomycetidae, each of them can infect a wide range of hosts.…”

“…The most common species are S. diclina, S. ferax, S. australis and S. parasitica (Ke et al, 2009). A study performed in Korea from fish identified seven isolates of saprolegniosis pathogens, morphological and molecular phylogenetic analysis of which permitted them to be identified as Achlya americana and A. bisexualis (Choi et al, 2019). Oomycetes isolated from cichlids in South Africa have been identified as A. bisexualis (Greeff-Laubscher et al, 2019).…”