Straminipile “Fungi” – Taxonomy

Abstract

The phylogeny and taxonomy of the mastigonate ‘fungal‐like’ organisms (stramenopiles) are described. The marine Labyrinthulomycota occur in the same stramenopile clade as the bioecids and opalinids, whilst the hyphochytrids and biflagellate oomycetes occur in a sister clade, together with the ochrophyte algae. The uniflagellate hyphochytrids are a small group whose closest relative appears to be the phagotrophic flagellate Pirsonia . The largest and best documented of the straminipile fungi are the oomycetes. There are a number of early diverging oomycete clades (Classes incertae sedis) consisting of mostly holocarpic marine species that are parasites of algae and invertebrates. The more advanced, largely freshwater and terrestrial fungal‐like oomycetes, fall into two main classes, the Saprolegniomycetes and Peronosporomycetes. The former largely encompasses the saprotrophic water moulds, whilst the latter contains the majority of the economically important plant pathogens, including the white blister rusts (Albuginales), Pythium, Phytophthora and the downy mildews (Peronosporales). Key Concepts Molecular phylogenetics reveals most bioflagellate fungal‐like organisms traditionally studied by mycologists and occur in the stramenopile (heterokont) clade within the SAR (formerly chromalveolate) superkingdom. These fungal‐like organisms have probably evolved from a photosynthetic flagellate ancestor and there have been several independent plastid loss events. The traditional taxonomy of all of these organisms has had to be substantially re‐evaluated in the light of recent molecular studies.

New insights into the evolutionary history of Fungi from a 407 Ma Blastocladiomycota fossil showing a complex hyphal thallus

“…However, the match to the modern species was not perfect and they noted that hyphal constrictions were not discernible in the fossil and that the oogonia and sporangia of A. pyrifera were smaller than the vesicles of the fossil. Nowadays the oomycetes and hyphochytrids, together with some marine flagellates, are included in the Heterokonta, along with the photosynthetic chromistan (golden-brown) algae, brown algae and diatoms [46,47]. We describe the fossil as a true zoosporic fungus.…”

Species Richness, rRNA Gene Abundance, and Seasonal Dynamics of Airborne Plant-Pathogenic Oomycetes

“…Oomycetes are one of the most economically important and widespread group of plant pathogens. They are a diverse group of “fungus-like” eukaryotic organisms distributed globally in diverse environments and spreading through water, seeds, soil, and air ( Göker et al, 2007 ; Dick, 2013 ; Beakes et al, 2015 ). Historically, Oomycetes were classified as fungi because of their similarities in hyphal organization and in nutrition (osmotrophy).…”

“…Historically, Oomycetes were classified as fungi because of their similarities in hyphal organization and in nutrition (osmotrophy). However, since their molecular analysis in recent years, they have been redefined as stramenopiles (or heterokonts), to which brown algae also belong ( Baldauf et al, 2000 ; Latijnhouwers et al, 2003 ; Andersen, 2004 ; Spring and Thines, 2004 ; Garcia-Blazquez et al, 2008 ; Riisberg et al, 2009 ; Dick, 2013 ; Beakes et al, 2015 ).…”

“…More than 60% of known Oomycetes species are plant pathogens, such as species from the families Albuginaceae (white blister rusts), Peronosporaceae (downy mildews), and Pythiaceae ( Aylor et al, 1982 ; Göker et al, 2007 ; Walker and van West, 2007 ; Garcia-Blazquez et al, 2008 ; Voglmayr, 2008 ; Thines and Kamoun, 2010 ; Beakes et al, 2015 ). An understanding of their diversity, dynamics, and spreading behavior in the atmosphere on local and larger scales is important to improve infection risk prediction and disease management strategies ( West et al, 2008 ).…”

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

“…The kingdom Straminipila is a remarkably diverse group that includes oomycetes, brown algae, and planktonic diatoms. The oomycetes have previously been classified under the kingdom Fungi, with which they share several convergent traits, such as osmotrophic nutrition and mycelial growth [1], thus often called “fungus-like organism” or “pseudo-fungi.” These organisms have evolved both pathogenic and saprophytic lifestyles. The largest subclass Peronosporomycetidae is mostly parasitic on plants [2], the vast majority of which was found on the order Peronosporales (includes Peronospora , Phytophthora , and Pythium ), which occur important diseases on crops, ornamental plants, and forest trees [3].…”