Martin Kirchmair

Proposed nomenclature for Pseudallescheria, Scedosporium and related genera

As a result of fundamental changes in the International Code of Nomenclature on the use of separate names for sexual and asexual stages of fungi, generic names of many groups should be reconsidered. Members of the ECMM/ISHAM working group on Pseudallescheria/Scedosporium infections herein advocate a novel nomenclature for genera and species in Pseudallescheria, Scedosporium and allied taxa. The generic names Parascedosporium, Lomentospora, Petriella, Petriellopsis, and Scedosporium are proposed for a lineage within Microascaceae with mostly Scedosporium anamorphs producing slimy, annellidic conidia. Considering that Scedosporium has priority over Pseudallescheria and that Scedosporium prolificans is phylogenetically distinct from the other Scedosporium species, some name changes are proposed. Pseudallescheria minutispora and Petriellidium desertorum are renamed as Scedosporium minutisporum and S. desertorum, respectively. Scedosporium prolificans is renamed as Lomentospora prolificans.

Cross-kingdom host shifts of phytomyxid parasites

BackgroundPhytomyxids (plasmodiophorids and phagomyxids) are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae. Plasmodiophorids are best known as pathogens or vectors for viruses of arable crops (e.g. clubroot in brassicas, powdery potato scab, and rhizomania in sugar beet). Some phytomyxid parasites are of considerable economic and ecologic importance globally, and their hosts include important species in marine and terrestrial environments. However most phytomyxid diversity remains uncharacterised and knowledge of their relationships with host taxa is very fragmentary.ResultsOur molecular and morphological analyses of phytomyxid isolates–including for the first time oomycete and sea-grass parasites–demonstrate two cross-kingdom host shifts between closely related parasite species: between angiosperms and oomycetes, and from diatoms/brown algae to angiosperms. Switching between such phylogenetically distant hosts is generally unknown in host-dependent eukaryote parasites. We reveal novel plasmodiophorid lineages in soils, suggesting a much higher diversity than previously known, and also present the most comprehensive phytomyxid phylogeny to date.ConclusionSuch large-scale host shifts between closely related obligate biotrophic eukaryote parasites is to our knowledge unique to phytomyxids. Phytomyxids may readily adapt to a wide diversity of new hosts because they have retained the ability to covertly infect alternative hosts. A high cryptic diversity and ubiquitous distribution in agricultural and natural habitats implies that in a changing environment phytomyxids could threaten the productivity of key species in marine and terrestrial environments alike via host shift speciation.

Amanita poisonings resulting in acute, reversible renal failure: new cases, new toxic Amanita mushrooms

BACKGROUND Renal failure as a consequence of eating mushrooms has been reported repeatedly after ingestion of webcaps of the Cortinarius orellanus group. But mushrooms of the genus Amanita can also cause renal failure: Amanita smithiana (North America) and Amanita proxima (Mediterranean area). Here, we discuss poisonings caused by other white amanitas. A German and--independently--two Portuguese patients reported the ingestion of completely white mushrooms with ring. Similar to intoxications with A. smithiana or A. proxima, the clinical picture was characterized by nausea and vomiting 10-12 h after ingestion, severe acute renal failure and mild hepatitis. Renal biopsy showed acute interstitial nephritis and tubular necrosis. Two patients were given temporary haemodialysis. All have fully recovered their renal function. Poisonings caused by mushrooms containing the toxin of A. smithiana were suspected. We tested 20 Amanita species for the presence of this toxin. METHODS Thin layer chromatography was applied to detect A. smithiana nephrotoxin in herbarium specimens using authentic material of A. smithiana as reference. RESULTS A. smithiana toxin could be detected in Amanita boudieri, Amanita gracilior and in Amanita echinocephala. A. boudieri was collected by the Portuguese patients. A. echinocephala is the only nephrotoxic Amanita growing North of the Alps and is suspected to be the cause of renal failure in the German patient. No A. smithiana toxin was detectable in the nephrotoxic A. proxima. CONCLUSIONS A. boudieri, A. gracilior and A. echinocephala are nephrotoxic. These intoxications are clinically similar to that of A. smithiana, with acute reversible renal failure and mild hepatitis but are different in their clinical picture from Orellanus syndrome characterized by a delayed onset of severe and often irreversible renal failure.

Ecological roles of the parasitic phytomyxids (plasmodiophorids) in marine ecosystems - a review

Phytomyxea (plasmodiophorids) is an enigmatic group of obligate biotrophic parasites. Most of the known 41 species are associated with terrestrial and freshwater ecosystems. However, the potential of phytomyxean species to influence marine ecosystems either directly by causing diseases of their hosts or indirectly as vectors of viruses is enormous, although still unexplored. In all, 20% of the currently described phytomyxean species are parasites of some of the key primary producers in the ocean, such as seagrasses, brown algae and diatoms; however, information on their distribution, abundance and biodiversity is either incomplete or lacking. Phytomyxean species influence fitness by altering the metabolism and/or the reproductive success of their hosts. The resulting changes can (1) have an impact on the biodiversity within host populations, and (2) influence microbial food webs because of altered availability of nutrients (e.g. changed metabolic status of host, transfer of organic matter). Also, phytomyxean species may affect their host populations indirectly by transmitting viruses. The majority of the currently known single-stranded RNA marine viruses structurally resemble the viruses transmitted by phytomyxean species to crops in agricultural environments. Here, we explore possible ecological roles of these parasites in marine habitats; however, only the inclusion of Phytomyxea in marine biodiversity studies will allow estimation of the true impact of these species on global primary production in the oceans.

Ecological functions of zoosporic hyperparasites

Zoosporic parasites have received increased attention during the last years, but it is still largely unnoted that these parasites can themselves be infected by hyperparasites. Some members of the Chytridiomycota, Blastocladiomycota, Cryptomycota, Hyphochytriomycota, Labyrinthulomycota, Oomycota, and Phytomyxea are hyperparasites of zoosporic hosts. Because of sometimes complex tripartite interactions between hyperparasite, their parasite-host, and the primary host, hyperparasites can be difficult to detect and monitor. Some of these hyperparasites use similar mechanisms as their parasite-hosts to find and infect their target and to access food resources. The life cycle of zoosporic hyperparasites is usually shorter than the life cycle of their hosts, so hyperparasites may accelerate the turnaround times of nutrients within the ecosystem. Hyperparasites may increase the complexity of food webs and play significant roles in regulating population sizes and population dynamics of their hosts. We suggest that hyperparasites lengthen food chains but can also play a role in conducting or suppressing diseases of animals, plants, or algae. Hyperparasites can significantly impact ecosystems in various ways, therefore it is important to increase our understanding about these cryptic and diverse organisms.

Plasmodiophorids: The Challenge to Understand Soil-Borne, Obligate Biotrophs with a Multiphasic Life Cycle

Plasmodiophorids are an enigmatic group of obligate biotrophic pathogens of higher plants. Together with their sister group phagomyxids, which infect stramenopiles, they form the monophyletic eukaryote clade phytomyxids. They have long been treated as a basal group of fungi, but recent molecular phylogenies point to a close affiliation with the protozoan phylum Cercozoa. The soil-borne and plant-associated nature of plasmodiophorids as well as their multi-stage life cycle with zoosporic, plasmodial, and resting stages has hindered comprehensive research on this group. Plasmodiophorids cannot be cultured without their hosts, and direct observations of any stage of the plasmodiophorid life cycle are difficult and time-consuming. Molecular techniques provide valuable tools for the identification and monitoring of organisms which are difficult to assess with traditional approaches – such as plasmodiophorids. Several different immunological or nucleic acid-based techniques, and more recently genomic and proteomic approaches have been used to investigate plasmodiophorids, their life style, and their interactions with their host plants. Nonetheless, advances in knowledge about plasmodiophorids provided by molecular techniques are mainly restricted to the few economically important species that cause diseases of agricultural crops. Although their taxa may be well described, the available phylogenies of phytomyxids are rather incomplete, as they include only a few selected species. A main reason for this bias is that most specimens deposited in herbaria are too old, soaked in fixatives or otherwise unavailable for DNA analyses. To fully understand this group of protists, more research on “rare”, under-recorded species is needed.

The ecological potentials of Phytomyxea (“plasmodiophorids”) in aquatic food webs

The Phytomyxea (“plasmodiophorids”) including both Plasmodiophorida and Phagomyxida is a monophyletic group of Eukaryotes composed of obligate biotrophic parasites of green plants, brown algae, diatoms and stramenopiles commonly found in many freshwater, soil and marine environments. However, most research on Phytomyxea has been restricted to plant pathogenic species with agricultural importance, thereby missing the huge ecological potential of this enigmatic group of parasites. Members of the Phytomyxea can induce changes in biomass in their hosts (e.g. hypertrophies of the host tissue) under suitable environmental conditions. Upon infection they alter the metabolism of their hosts, consequently changing the metabolic status of their host. This results in an altered chemical composition of the host tissue, which impacts the diversity of species which feed on the tissues of the infected host and on the zoospores produced by the parasites. Furthermore, significant amounts of nutrients derived from the hosts, both primary producers (plants and algae) and primary consumers (litter decomposers and plant parasites [Oomycetes]), can enter the food web at different trophic levels in form of zoospores and resting spores. Large numbers of zoospores and resting spores are produced which can be eaten by secondary and tertiary consumers, such as grazing zooplankton and metazoan filter-feeders. Therefore, these microbes can act as energy-rich nutrient resources which may significantly alter the trophic relationships in fresh water, soil and marine habitats. Based on the presented data, Phytomyxea can significantly contribute to the complexity and energy transfer within food webs.

Short Communication - Antifungal properties of 5-hydroxytryptamine (serotonin) against Aspergillus spp. in vitro

This study shows that 5-hydroxytrypatmine (5-HT, serotonin) is fungicidal towards conidia and hyphae of clinical isolates of Aspergillus (A.) fumigatus, A. flavus and A. terreus. The minimal fungicidal concentrations for Aspergillus conidia and hyphae ranged between 14.68 to 117.5 mM and 29.37 to 235 mM during 24 and 48 h of incubation. Several serotonin receptor antagonists (5-HT2, 5-HT3) studied in vitro did not influence antifungal activity.

Laboratory confirmation of Amanita smithiana mushroom poisoning

Context. Here we present a case of Amanita smithiana poisoning resulting in acute kidney injury requiring dialysis, and highlight laboratory methods used to confirm the diagnosis. Identification of Amanita smithiana toxin using thin-layer chromatography can provide greater diagnostic certainty than history and renal function tests alone. Case details. A 63-year-old male presented to hospital with anuria and gastrointestinal symptoms, two days after consuming a soup of wild mushrooms he had picked. He was found to be in acute renal failure, requiring hemodialysis. After nine days of supportive treatment, he recovered renal function, and was discharged in good health 15 days post-ingestion. The patient provided a sample of leftover soup, and examination of cooked mushroom fragments by a mycologist provided preliminary identification of A. smithiana. Thin-layer chromatography revealed the presence of A. smithiana toxin in the soup, confirming this identification. Discussion. A. smithiana is a nephrotoxic mushroom that can be easily mistaken for the edible and highly prized Pine mushroom (Tricholoma magnivelare). It causes initial gastrointestinal symptoms, followed by acute renal failure. Treatment includes dialysis and supportive care until the patient recovers renal function. The chemical structure of the A. smithiana toxin is unknown, but it can be identified as a characteristic spot on thin-layer chromatography.

The taxonomic position of Roesleria subterranea.

The genus Roesleria was introduced with the single species Roesleria hypogaea (current name: R. subterranea) by Thümen in 1877. The species was originally described from roots of grapevine and recognised as a facultative root-rotting parasite. The mazaediate ascoma with evanescent asci led to the assumption that Roesleria would be an ally of mazaediate lichens. In this study we calculate 28S, 18S as well ITS1-5.8S-ITS2 rDNA phylogenies. These data indicate that Roesleria is closely related to Hymenoscyphus (Helotiales). In contrast to other members of the Helotiales, the ascospores of Roesleria are passively released, and a distinct apical apparatus cannot be observed by LM. Electron optic investigations have also not elucidated whether the asci of Roesleria are equipped with a rudimentary apical apparatus or not. The passive release of the ascospores is discussed as an apomorphic character that evolved as adaptation to a hypogeous living.