Broad host range species in specialised pathogen groups should be treated with suspicion – a case study on Entyloma infecting Ranunculus

Plant pathogenic smut fungi in the broader sense can be divided into the Ustilaginomycetes, which cause classical smut symptoms with masses of blackish spores being produced in a variety of angiosperms, and the Exobasidiomycetes, which are often less conspicuous, as many do not shed large amounts of blackish spores. The leaf-spot causing members of the genus Entyloma (Entylomatales, Exobasidiomycetes) belong to the latter group. Currently, 172 species that all infect eudicots are included in the genus. Vánky (2012) recognised five Entyloma species on species of Ranunculus s.lat. Two have been reported only from Ficaria verna s.lat., while three, E. microsporum, E. ranunculi-repentis, E. verruculosum, have been reported to have a broad host range, encompassing 30, 26, and 5 species of Ranunculus, respectively. This broad host range is in contrast to the generally high host specificity assumed for species of Entyloma, indicating that they may represent complexes of specialised species. The aim of this study was to investigate Entyloma on Ranunculus s.lat. using multigene phylogenies and morphological comparisons. Phylogenetic analyses on the basis of up to four loci (ITS, atp2, ssc1, and map) showed a clustering of Entyloma specimens according to host species. For some of these Entyloma lineages, names not currently in use were available and reinstated. In addition, Entyloma microsporum s.str. is neotypified. Six novel species are described in this study, namely, Entyloma jolantae on Ranunculus oreophilus, E. klenkei on R. marginatus, E. kochmanii on R. lanuginosus, E. piepenbringiae on R. polyanthemos subsp. nemorosus (type host) and R. repens, E. savchenkoi on R. paludosus, and E. thielii on R. montanus. For all species diagnostic bases and morphological characteristics are provided. The results in this study once more highlight the importance of detailed re-investigation of broad host-range pathogens of otherwise specialised plant pathogen groups

Phytopythium leanoi sp. nov. and Phytopythium dogmae sp. nov., Phytopythium species associated with mangrove leaf litter from the Philippines

The genus Phytopythium is a monophyletic taxon of the Peronosporaceae with characteristics intermediate between Phytophthora and Pythium. In the Philippines, reports of Phytopythium are scarce, with the mangrove-swamp-inhabiting species Phytopythium kandeliae being the only species recorded to date. It was the aim of the current study to investigate the diversity of Phytopythium in mangrove habitats in more detail. Based on culture characteristics, morphology, and molecular phylogenetic position, two new species of Phytopythium are described from Philippine mangroves, P. leanoi USTCMS 4102 and P. dogmae USTCMS 4101. Phytopythium leanoi is a species morphologically similar to P. kandeliae, but with the ability to develop gametangia in a homothallic fashion. The other new species, P. dogmae, is characterized by having a short discharge tube, semipapillate to papillate sporangia and frequently exhibiting a clustering of two sporangia per sporangiogenic hypha. With the addition of the two species described in this study, the genus Phytopythium has grown from around 10 to beyond 20 recognized species over the past decade, and it seems likely that several more species of this genus await discovery

Salisapiliaceae – a new family of oomycetes from marsh grass litter of southeastern North America

Several filamentous oomycete species of the genus Halophytophthora have recently been described from marine environments, mostly from subtropical and tropical ecosystems. During a survey of oomycetes from leaf litter of Spartina alterniflora in salt marshes of southeastern Georgia, isolates of four taxa were recovered that bore similarity to some members of Halophytophthora but were highly divergent from isolates of Halophytophthora s.str. based on a combined sequence analysis of two nuclear loci. In phylogenetic analyses, these isolates were placed basal to a monophyletic group comprised of Pythium of the Pythiaceae and the Peronosporaceae. Sequence and morphology of these taxa diverged from the type species Halophytophthora vesicula, which was placed within the Peronosporaceae with maximum support. As a consequence a new family, the Salisapiliaceae, and a new genus, Salisapilia, are described to accommodate the newly discovered species, along with one species previously classified within Halophytophthora. Morphological features that separate these taxa from Halophytophthora are a smaller hyphal diameter, oospore production, lack of vesicle formation during sporulation, and a plug of hyaline material at the sporangial apex that is displaced during zoospore release. Our findings offer a first glance at the presumably much higher diversity of oomycetes in estuarine environments, of which ecological significance requires further exploration

Ferulic acid is a putative surrender signal to stimulate programmed cell death in grapevines after infection with Neofusicoccum parvum

An apoplectic breakdown from grapevine trunk diseases (GTDs) has become a serious challenge to viticulture as a consequence of drought stress. We hypothesize that fungal aggressiveness is controlled by a chemical communication between the host and colonizing fungus. We introduce the new concept of a ‘plant surrender signal’ accumulating in host plants under stress and facilitating the aggressive behaviour of the strain Neofusicoccum parvum (Bt-67) causing Botryosphaeriaceae-related dieback in grapevines. Using a cell-based experimental system (Vitis cells) and bioactivity-guided fractionation, we identify trans-ferulic acid, a monolignol precursor, as a ‘surrender signal’. We show that this signal specifically activates the secretion of the fungal phytotoxin fusicoccin A aglycone. We show further that this phytotoxin, mediated by 14-3-3 proteins, activates programmed cell death in Vitis cells. We arrive at a model showing a chemical communication facilitating fusicoccin A secretion that drives necrotrophic behaviour during Botryosphaeriaceae–Vitis interaction through trans-ferulic acid. We thus hypothesize that channelling the phenylpropanoid pathway from this lignin precursor to the trans-resveratrol phytoalexin could be a target for future therapy

Bridging the Gulf: Phytophthora and Downy Mildews Are Connected by Rare Grass Parasites

Downy mildews and root and foliar rots caused by Phytophthora are among the most destructive plant pathogens and therefore have attracted considerable attention during the past two decades. Although it has been realized that a close phylogenetic relationship exists, so far sharp distinction has been made between the obligate biotrophic downy mildews and the hemibiotrophic Phytophthora. In the study presented here, it is shown that a continuum of character states from hemibiotrophic Phytophthora species to obligate biotrophic downy mildews is present. Intermediate character states between downy mildews and Phytophthora species exist in several rare parasites of grasses, which are not embedded within the major clades of the downy mildews but are placed sister to these, with unresolved affinities to both these clades and to Phytophthora. They still have retained traits hitherto thought to be exclusive for Phytophthora. A careful review of previous research is presented and it is highlighted that uniquely for downy mildews, Poakatesthia may form an intracellular mycelium, growing through several host cells. In addition, scanning electron microscopy reveals that sporangiophore growth is not determinate in Viennotia and that outgrowth from sporangiophores is very similar to Phytophthora infestans. It is concluded that the sharp morphological distinction between downy mildews and Phytophthora species (that are often placed in separate families and even different orders), is rather artificial, since all features thought to be exclusive to Phytophthora or the downy mildews are united in the rare grass-parasitizing down mildew genera Viennotia and Poakatesthia and the enigmatic genus Sclerophthora. Therefore, several paradigms regarding the distinction between Phytophthora and the downy mildews need to be reconsidered

Intrasellar rupture of a paraclinoid aneurysm with subarachnoid hemorrhage: usefulness of MR imaging in diagnosis

Characterization of paraclinoid aneurysms may be difficult because of the complexity of anatomic structures involved, and differentiation between intradural and extradural lesions is crucial. We report a case of a patient with a unique presentation of a paraclinoid aneurysm with intrasellar hemorrhage in which the presence of intrasellar blood and the relationship of the paraclinoid aneurysmal neck and sac to the dural rings were elegantly demonstrated on MR imaging and were critical in choosing the target lesion for treatment

The rise and fall of the Phytophthora infestans lineage that triggered the Irish potato famine

Phytophthora infestans, the cause of potato late blight, is infamous for having triggered the Irish Great Famine in the 1840s. Until the late 1970s, P. infestans diversity outside of its Mexican center of origin was low, and one scenario held that a single strain, US-1, had dominated the global population for 150 years; this was later challenged based on DNA analysis of historical herbarium specimens. We have compared the genomes of 11 herbarium and 15 modern strains. We conclude that the nineteenth century epidemic was caused by a unique genotype, HERB-1, that persisted for over 50 years. HERB-1 is distinct from all examined modern strains, but it is a close relative of US-1, which replaced it outside of Mexico in the twentieth century. We propose that HERB-1 and US-1 emerged from a metapopulation that was established in the early 1800s outside of the species' center of diversity.Comment: To be published in eLIF

A dynamic portal for a community-driven, continuously updated classification of Fungi and fungus-like organisms: outlineoffungi.org

The website http://outlineoffungi.org, is launched to provide a continuous up-to-date classification of the kingdom Fungi (including fossil fungi) and fungus-like taxa. This is based on recent publications and on the outline of fungi and fungus-like taxa published recently (Mycosphere 11, 1060-1456, Doi: 10.5943/mycosphere/11/1/8). The website is continuously updated according to latest classification schemes, and will present an important platform for researchers, industries, government officials and other users. Users can provide input about missing genera, new genera, and new data. They will also have the opportunity to express their opinions on classifications with notes published in the 'Notes' section of the webpage following review and editing by the curators and independent experts. The website will provide a system to stay abreast of the continuous changes in fungal classification and provide a general consensus on the systematics of fungi

The fungal metabolite 4‐hydroxyphenylacetic acid from Neofusicoccum parvum modulates defence responses in grapevine

In a consequence of global warming, grapevine trunk diseases (GTDs) have become a pertinent problem to viticulture, because endophytic fungi can turn necrotrophic upon host stress killing the plant. In Neofusicoccum parvum Bt-67, plant-derived ferulic acid makes the fungus release Fusicoccin aglycone triggering plant cell death. Now, we show that the absence of ferulic acid lets the fungus secrete 4-hydroxyphenylacetic acid (4-HPA), mimicking the effect of auxins on grapevine defence and facilitating fungal spread. Using Vitis suspension cells, we dissected the mode of action of 4-HPA during defence triggered by the bacterial cell-death elicitor, harpin. Early responses (cytoskeletal remodelling and calcium influx) are inhibited, as well as the expression of Stilbene Synthase 27 and phytoalexin accumulation. In contrast to other auxins, 4-HPA quells transcripts for the auxin conjugating GRETCHEN HAGEN 3. We suggest that 4-HPA is a key component of the endophytic phase of N. parvum Bt-67 preventing host cell death. Therefore, our study paves the way to understand how GTDs regulate their latent phase for successful colonisation, before turning necrotrophic and killing the vines