Long-read PacBio genome sequencing of four environmental saprophytic Sporothrix species spanning the pathogenic clade

BACKGROUND

The genus Sporothrix belongs to the order Ophiostomatales and contains mainly saprobic soil and plant fungi, although pathogenic species capable of causing human infections are also present. The whole-genomes of disease-causing species have already been sequenced and annotated but no comprehensive genomic resources for environmental Sporothrix species are available, thus limiting our understanding of the evolutionary origin of virulence-related genes and pathogenicity.

RESULT

The genome assembly of four environmental Sporothrix species resulted in genome size of ~ 30.9 Mbp in Sporothrix phasma, ~ 35 Mbp in S. curviconia, ~ 38.7 Mbp in S. protearum, and ~ 39 Mbp in S. variecibatus, with a variable gene content, ranging from 8142 (S. phasma) to 9502 (S. variecibatus). The analysis of mobile genetic elements showed significant differences in the content of transposable elements within the sequenced genomes, with the genome of S. phasma lacking several class I and class II transposons, compared to the other Sporothrix genomes investigated. Moreover, the comparative analysis of orthologous genes shared by clinical and environmental Sporothrix genomes revealed the presence of 3622 orthogroups shared by all species, whereas over 4200 genes were species-specific single-copy gene products. Carbohydrate-active enzyme analysis revealed a total of 2608 protein-coding genes containing single and/or multiple CAZy domains, resulting in no statistically significant differences among pathogenic and environmental species. Nevertheless, some families were not found in clinical species. Furthermore, for each sequenced Sporothrix species, the mitochondrial genomes was assembled in a single circular DNA molecule, ranging from 25,765 bp (S. variecibatus) to 58,395 bp (S. phasma).

CONCLUSION

In this study, we present four annotated genome assemblies generated using PacBio SMRT sequencing data from four environmental species: S. curviconia, S. phasma, S. protearum and S. variecibatus with the aim to provide a starting point for future comparative genome evolution studies addressing species diversification, ecological/host adaptation and origin of pathogenic lineages within the genus Sporothrix.

Ceratocystiopsis quercina sp. nov. Associated with Platypus cylindrus on Declining Quercus suber in Portugal

Platypus cylindrus is the most common ambrosia beetle in stands of Quercus suber in Portugal. This insect farms specialized fungi in sapwood galleries, using its mycangia to carry and store these organisms. Some ectosymbiotic fungi carried by P. cylindrus are phytopathogenic and cause extensive tree mortality and severe economic losses. To understand the role of P. cylindrus fungal symbionts in stands of Q. suber we examined beetle galleries present in declining and/or dying cork oak trees during field surveys. Logs with active galleries were obtained in situ and from captured emerging beetles. Insects were aseptically dissected, and their mycangia and intestine were retrieved. Morphological and molecular profiles of fungal isolates obtained from cultured insect parts were carried out to accurately characterize and identify isolated fungi. Molecular characterizations were performed with DNA sequence data from four loci, i.e., LSU, SSU, 5.8S-ITS2-28S, and TUB. Morphological results consistently showed a collection of Ophiostoma-like fungal axenic isolates, while phylogenies inferred that this collection constitutes an undescribed taxon reported herein for the first time in association with P. cylindrus in Portuguese cork oak stands. The novel species was erected as Ceratocystiopsis quercina sp. nov. and constitutes a new phytopathogenic fungal species associated with symptoms of vegetative cork oak decline.

Persistence of ecologically similar fungi in a restricted floral niche

Fungi in the genera Knoxdaviesia and Sporothrix dominate fungal communities within Protea flowerheads and seed cones (infructescences). Despite apparently similar ecologies, they show strong host recurrence and often occupy the same individual infructescence. Differences in host chemistry explain their host consistency, but the factors that allow co-occupancy of multiple species within individual infructescences are unknown. Sporothrix splendens and K. proteae often grow on different senescent tissue types within infructescences of their P. repens host, indicating that substrate-related differences aid their co-occupancy. Sporothrix phasma and K. capensis grow on the same tissues of P. neriifolia suggesting neutral competitive abilities. Here we test the hypothesis that differences in host-tissues dictate competitive abilities of these fungi and explain their co-occupancy of this spatially restricted niche. Media were prepared from infructescence bases, bracts, seeds, or pollen presenters of P. neriifolia and P. repens. As expected, K. capensis was unable to grow on seeds whilst S. phasma could. As hypothesised, K. capensis and S. phasma had equal competitive abilities on pollen presenters, appearing to explain their co-occupancy of this resource. Growth of K. proteae was significantly enhanced on pollen presenters while that of S. splendens was the same as the control. Knoxdavesia proteae grew significantly faster than S. splendens on all tissue types. Despite this, S. splendens was a superior competitor on all tissue types. For K. proteae to co-occupy infructescences with S. splendens for extended periods, it likely needs to colonize pollen presenters before the arrival of S. splendens.

Six new species of Sporothrix from hardwood trees in Poland

Sporothrix (Sordariales, Ascomycota) is a well-supported monophyletic lineage within the Ophiostomatales, species of which occur in a diverse range of habitats including on forest trees, in the soil, associated with bark beetles and mites as well as on the fruiting bodies of some Basidiomycota. Several species have also been reported as important human and animal pathogens. During surveys of insect- and wound-associated Ophiostomatales from hardwood trees in Poland, many isolates with affinity to Sporothrix were recovered. In the present study, six undescribed Sporothrix spp. collected during these surveys are characterized based on their morphological characteristics and multi-locus phylogenenetic inference. They are described as Sporothrixcavum, Sporothrixcracoviensis, S.cryptarchum, S.fraxini, S.resoviensis, and S.undulata. Two of the Sporothrix spp. reside in the S.gossypina-complex, while one forms part of the S.stenoceras-complex. One Sporothrix sp. is a member of lineage F, and two other species grouped outside any of the currently defined species complexes. All the newly described species were recovered from hardwood habitats in association with sub-cortical insects, wounds or woodpecker cavities. These species were morphologically similar, with predominantly asexual states having hyaline or lightly pigmented conidia, which produce holoblastically on denticulate conidiogenous cells. Five of the new taxa produce ascomata with necks terminating in long ostiolar hyphae and allantoid ascospores without sheaths. The results suggest that Sporothrix species are common members of the Ophiostomatales in hardwood ecosystems of Poland.

Interplay between differential competition and actions of spore-vectors explain host exclusivity of saprobic fungi in Protea flowers

Protea flowers host saprobic Knoxdaviesia and Sporothrix fungi that are dispersed by pollinating insects and birds. Different Protea species contain sympatric populations of different fungal species. For example, P. repens host S. splendens and K. proteae, while P. neriifolia host K. capensis and S. phasma. Even though all fungi can grow vigorously on alternative hosts and they share the same spore vector species, they rarely colonise alternative hosts. We investigated the role of fungal differential competitive abilities on their usual and alternative hosts to explain their host exclusivity. In a de Wit replacement series experiment, S. splendens outcompeted and later overgrew all other fungi on media prepared from its usual and alternative hosts. Host exclusivity of S. splendens on P. repens may therefore be maintained by restricted movement of spore vectors rather than weaker competitive abilities on alternative hosts. On their preferred hosts, S. splendens and S. phasma rapidly overgrew Knoxdavesia species with which they do not usually share a host, explaining host exclusivity of the Knoxdavesia species. Knoxdaviesia proteae likely only persist on P. repens with sympatric S. splendens if it colonizes flowers earlier, in a different area, or completes its life cycle before being overgrown. On their usual P. neriifolia host, K. capensis and S. phasma had neutralistic interactions and S. phasma could not overgrow K. capensis, explaining their co-existence. Host exclusivity of saprobic Protea-associated Knoxdaviesia and Sporothrix may therefore be maintained by both the activities of spore vectors and differential competitive abilities on different hosts, but the influence of other competing microbes and micro-niche differentiation cannot be excluded.

A new species of Raffaelea from beetle-infested Leucaena leucocephala

Species of Raffaelea (Ophiostomatales: Ascomycota) are obligate symbionts of ambrosia beetles, some of which pose a substantial threat to forest trees. Leucaena leucocephala is a small mimosoid tree species that is considered as an invasive weed in most of its introduced range globally. During a field expedition on the French island of Réunion, dying L. leucocephala trees were observed. Samples were taken from these trees and isolations made from symptomatic wood tissues that included beetle tunnels, but in the absence of the beetles themselves. Multiple isolates of a fungus resembling a Raffaelea species were obtained from the discoloured wood associated with the beetle tunnels. To determine their identity, microscopic examination was performed and DNA sequences for three gene regions (ITS, LSU, TUB) were obtained. Phylogenetic analyses based on these gene regions revealed that the isolates represent a new species of Raffaelea, described here as R. borbonica sp. nov. A pathogenicity test was conducted with the fungus, which was shown to cause lesions on the inoculated seedlings, but with a low level of aggressiveness.

The threat of emerging and re-emerging pathogenic Sporothrix species

Sporotrichosis is a neglected subcutaneous mycosis of humans and animals acquired by traumatic inoculation of soil and plant material (classical route) contaminated with infectious propagules of the pathogen or being bitten/scratched by infected cats (alternative route). Within a genus composed of 53 species displaying an essentially environmental core, there are only a few members which have considerable impacts on human or animal health. Infections are typically caused by S. brasiliensis, S. schenckii or S. globosa. Rare mammal pathogens include members of the S. pallida and S. stenocereus complexes. To illustrate the tremendous impact of emerging zoonotic sporotrichosis on public health, we discuss the main features of the expanding epidemics driven by S. brasiliensis in cats and humans. The cat entry in the transmission chain of sporotrichosis, causing epizooties (cat-cat) or zoonosis (cat-human), has contributed to the definition of new paradigms in Sporothrix transmission, reaching epidemic levels, making the disease a serious public health problem. Indeed, S. brasiliensis infection in humans and animals is likely to become even more important in the future, with projections of its expansion in biogeographic domains and host range, as well as greater virulence in mammals. Therefore, lessons from a long-standing outbreak in the state of Rio de Janeiro about the source and distribution of the etiological agents among outbreak areas can be used to create better control and prevention plans and increase awareness of sporotrichosis as a serious emerging zoonotic disease.

Draft genome sequences of five Calonectria species from Eucalyptus plantations in China, Celoporthe dispersa, Sporothrix phasma and Alectoria sarmentosa

Draft genome sequences of five Calonectria species [including Calonectria aciculata, C. crousiana, C. fujianensis, C. honghensis and C. pseudoturangicola], Celoporthe dispersa, Sporothrix phasma and Alectoria sarmentosa are presented. Species of Calonectria are the causal agents of Eucalyptus leaf blight disease, threatening the growth and sustainability of Eucalyptus plantations in China. Celoporthe dispersa is the causal agent of stem canker in native Syzygium cordatum and exotic Tibouchina granulosa in South Africa. Sporothrix phasma was first discovered in the infructescences of Protea laurifolia and Protea neriifolia in South Africa. Alectoria sarmentosa is fruticose lichen belongs to the alectorioid clade of the family Parmeliaceae. The availability of these genome sequences will facilitate future studies on the systematics, population genetics, and genomics of these fungi.

Genomic overview of closely related fungi with different Protea host ranges

Genome comparisons of species with distinctive ecological traits can elucidate genetic divergence that influenced their differentiation. The interaction of a microorganism with its biotic environment is largely regulated by secreted compounds, and these can be predicted from genome sequences. In this study, we considered Knoxdaviesia capensis and Knoxdaviesia proteae, two closely related saprotrophic fungi found exclusively in Protea plants. We investigated their genome structure to compare their potential inter-specific interactions based on gene content. Their genomes displayed macrosynteny and were approximately 10 % repetitive. Both species had fewer secreted proteins than pathogens and other saprotrophs, reflecting their specialized habitat. The bulk of the predicted species-specific and secreted proteins coded for carbohydrate metabolism, with a slightly higher number of unique carbohydrate-degrading proteins in the broad host-range K. capensis. These fungi have few secondary metabolite gene clusters, suggesting minimal competition with other microbes and symbiosis with antibiotic-producing bacteria common in this niche. Secreted proteins associated with detoxification and iron sequestration likely enable these Knoxdaviesia species to tolerate antifungal compounds and compete for resources, facilitating their unusual dominance. This study confirms the genetic cohesion between Protea-associated Knoxdaviesia species and reveals aspects of their ecology that have likely evolved in response to their specialist niche.

Ophiostomatoid fungi associated with pines infected by Bursaphelenchus xylophilus and Monochamus alternatus in China, including three new species

The activity of the pine wood nematodeBursaphelenchusxylophilusleads to extremely serious economic, ecological and social losses in East Asia. The nematode causes pine wilt disease, which is currently regarded as the most important forest disease in China. The pathogenic nematode feeds on dendrocola fungi to complete its cycle of infection. As the vector of the nematode, the Japanese pine sawyer (Monochamusalternatus) also carries dendrocola fungi. Pine woods, infected byB.xylophilusand tunnelled byM.alternatus, are also inhabited by ophiostomatoid fungi. These fungi are well known for their association with many bark and ambrosia beetles. They can cause sapstain and other serious tree diseases. The aims of our study were to investigate and identify the ophiostomatoid communities associated with the epidemic pine wood nematode and the pine sawyer inPinusmassonianaandP.thunbergiiforests, which are the main hosts of the pine wood nematode in China. Two hundred and forty strains of ophiostomatoid fungi were isolated from nematode and sawyer–infected trees in the coastal Shandong and Zhejiang Provinces, representing newly and historically infected areas, respectively. Six ophiostomatoid species were identified on the basis of morphological, physiological and molecular data. For the latter, DNA sequences of the internal transcribed spacer (ITS1–5.8S–ITS2) region and partial b-tubulin gene were examined. The ophiostomatoid species included one known species,Ophiostomaips, three novel species, viz.Ophiostomaalbumsp. nov.,Ophiostomamassonianasp. nov.andSporothrixzhejiangensissp. nov.and two species whose identities are still uncertain, Ophiostomacf.deltoideosporum and Graphilbumcf.rectangulosporium, due to the paucity of the materials obtained. The ophiostomatoid community was dominated byO.ips. This study revealed that a relatively high species diversity of ophiostomatoid fungi are associated with pine infected byB.xylophilusandM.alternatusin China.

Ophiostomatoid fungi associated with pines infected by Bursaphelenchusxylophilus and Monochamusalternatus in China, including three new species

The activity of the pine wood nematode Bursaphelenchusxylophilus leads to extremely serious economic, ecological and social losses in East Asia. The nematode causes pine wilt disease, which is currently regarded as the most important forest disease in China. The pathogenic nematode feeds on dendrocola fungi to complete its cycle of infection. As the vector of the nematode, the Japanese pine sawyer (Monochamusalternatus) also carries dendrocola fungi. Pine woods, infected by B.xylophilus and tunnelled by M.alternatus, are also inhabited by ophiostomatoid fungi. These fungi are well known for their association with many bark and ambrosia beetles. They can cause sapstain and other serious tree diseases. The aims of our study were to investigate and identify the ophiostomatoid communities associated with the epidemic pine wood nematode and the pine sawyer in Pinusmassoniana and P.thunbergii forests, which are the main hosts of the pine wood nematode in China. Two hundred and forty strains of ophiostomatoid fungi were isolated from nematode and sawyer-infected trees in the coastal Shandong and Zhejiang Provinces, representing newly and historically infected areas, respectively. Six ophiostomatoid species were identified on the basis of morphological, physiological and molecular data. For the latter, DNA sequences of the internal transcribed spacer (ITS1-5.8S-ITS2) region and partial b-tubulin gene were examined. The ophiostomatoid species included one known species, Ophiostomaips, three novel species, viz. Ophiostomaalbum sp. nov., Ophiostomamassoniana sp. nov. and Sporothrixzhejiangensis sp. nov. and two species whose identities are still uncertain, Ophiostomacf.deltoideosporum and Graphilbumcf.rectangulosporium, due to the paucity of the materials obtained. The ophiostomatoid community was dominated by O.ips. This study revealed that a relatively high species diversity of ophiostomatoid fungi are associated with pine infected by B.xylophilus and M.alternatus in China.

Two new Sporothrix species from Protea flower heads in South African Grassland and Savanna

The inflorescences and infructescences of African Protea trees provide habitat for a large diversity of Sporothrix species. Here we describe two additional members, Sporothrix nsini sp. nov. and Sporothrix smangaliso sp. nov., that are associated with the infructescences of various Protea species from grasslands and savannas in the KwaZulu-Natal, North-West, Gauteng and Mpumalanga provinces of South Africa. Their description raises the number of described Protea-associated Sporothrix species to twelve. S. smangaliso sp. nov. is distantly related to other Protea-associated species and, in phylogenies using multiple markers (ITS, beta-tubulin and calmodulin), groups with taxa such as Sporothrix bragantina from Brazil and Sporothrix curviconia from the Ivory Coast. S. nsini sp. nov. resolved as sister to a clade containing four other Protea-associated species within the Sporothrix stenoceras complex. S. nsini sp. nov. was collected from within the same infructescences of Protea caffra that also contained the closely related S. africana and S. protearum. This highlights the need to study and understand the factors that influence host selection and speciation of Sporothrix in this atypical niche.

Antifungal Streptomyces spp. Associated with the Infructescences of Protea spp. in South Africa

Common saprophytic fungi are seldom present in Protea infructescences, which is strange given the abundance of mainly dead plant tissue in this moist protected environment. We hypothesized that the absence of common saprophytic fungi in Protea infructescences could be due to a special symbiosis where the presence of microbes producing antifungal compounds protect the infructescence. Using a culture based survey, employing selective media and in vitro antifungal assays, we isolated antibiotic producing actinomycetes from infructescences of Protea repens and P. neriifolia from two geographically separated areas. Isolates were grouped into three different morphological groups and appeared to be common in the Protea spp. examined in this study. The three groups were supported in 16S rRNA and multi-locus gene trees and were identified as potentially novel Streptomyces spp. All of the groups had antifungal activity in vitro. Streptomyces sp. Group 1 had inhibitory activity against all tested fungi and the active compound produced by this species was identified as fungichromin. Streptomyces spp. Groups 2 and 3 had lower inhibition against all tested fungi, while Group 3 showed limited inhibition against Candida albicans and Sporothrix isolates. The active compound for Group 2 was also identified as fungichromin even though its production level was much lower than Group 1. The antifungal activity of Group 3 was linked to actiphenol. The observed antifungal activity of the isolated actinomycetes could contribute to protection of the plant material against common saprophytic fungi, as fungichromin was also detected in extracts of the infructescence. The results of this study suggest that the antifungal Streptomyces spp. could play an important role in defining the microbial population associated with Protea infructescences.

The divorce of Sporothrix and Ophiostoma: solution to a problematic relationship

One of the causal agents of human sporotrichosis, Sporothrix schenckii, is the type species of the genus Sporothrix. During the course of the last century the asexual morphs of many Ophiostoma spp. have also been treated in Sporothrix. More recently several DNA-based studies have suggested that species of Sporothrix and Ophiostoma converge in what has become known as Ophiostoma s. lat. Were the one fungus one name principles adopted in the Melbourne Code to be applied to Ophiostoma s. lat., Sporothrix would have priority over Ophiostoma, resulting in more than 100 new combinations. The consequence would be name changes for several economically important tree pathogens including O. novo-ulmi. Alternatively, Ophiostoma could be conserved against Sporothrix, but this would necessitate changing the names of the important human pathogens in the group. In this study, we sought to resolve the phylogenetic relationship between Ophiostoma and Sporothrix. DNA sequences were determined for the ribosomal large subunit and internal transcribed spacer regions, as well as the beta-tubulin and calmodulin genes in 65 isolates. The results revealed Sporothrix as a well-supported monophyletic lineage including 51 taxa, distinct from Ophiostoma s. str. To facilitate future studies exploring species level resolution within Sporothrix, we defined six species complexes in the genus. These include the Pathogenic Clade containing the four human pathogens, together with the S. pallida-, S. candida-, S. inflata-, S. gossypina- and S. stenoceras complexes, which include environmental species mostly from soil, hardwoods and Protea infructescences. The description of Sporothrix is emended to include sexual morphs, and 26 new combinations. Two new names are also provided for species previously treated as Ophiostoma.

Seasonal Succession of Fungi Associated with Ips typographus Beetles and Their Phoretic Mites in an Outbreak Region of Finland

The ophiostomatoid fungi (Microascales and Ophiostomatales, Ascomycota) are common associates of Ips typographus, and include tree pathogens and species responsible for blue-stain of timber. Fungal assemblages associated with I. typographus have varied considerably between studies but few investigations have attempted to explain this variation. For this reason, we assessed the overall cultivable fungal diversity associated with I. typographus in a storm-felled spruce forest in south-eastern Finland. Fungi were isolated from the individually collected beetles as well as their phoretic mites in spring, summer and autumn, including different life stages of the beetle (hibernation, dispersal flight and first generation). The internal transcribed spacer (ITS) gene region was used to identify the fungi. A total of 32 operational taxonomic units (OTUs) were found and these resided in four fungal phyla/subphyla (24 Ascomycota, 2 Basidiomycota, 5 Mucoromycotina, 1 Mortierellomycotina) in association with adult bark beetles. Ophiostomatoid species were the most commonly detected fungal associates. A generalized linear model analysis showed a clear association between fungal communities and season, indicating seasonal succession among I. typographus-associated fungi. The season of sampling appears to be an important factor that has resulted in inconsistencies between results in previous studies. Many of these fungi were also found on phoretic mites and their presence or absence could have influenced variation in patterns of association.

Molecular Components of the Sporothrix schenckii Complex that Induce Immune Response

Sporotrichosis is a fungal disease caused by the Sporothrix schenckii complex that includes species such as S. brasiliensis, S. schenckii sensu stricto, S. globosa, S. luriei, S. mexicana, and S. pallida, which exhibit different potentially antigenic molecular components. The immune response of susceptible hosts to control infection and disease caused by these fungi has been little studied. Besides, the fungus-host interaction induces the activation of different types of immune response. This mini-review analyzes and discusses existing reports on the identification and functional characterization of molecules from species of the S. schenckii complex with clinical relevance, and the mechanisms that mediate the type and magnitude of the immune response in experimental models in vivo and in vitro. This knowledge is expected to contribute to the development of protective and therapeutic strategies against sporotrichosis and other mycoses.

Wounds on Rapanea melanophloeos provide habitat for a large diversity of Ophiostomatales including four new species

Rapanea melanophloeos, an important canopy tree in Afromontane forests, is commonly utilised for medicinal bark harvesting. Wounds created from these activities provide entrance for many fungi, including arthropod-associated members of the Ophiostomatales and Microascales (ophiostomatoid fungi). In this study we assessed the diversity of wound-associated Ophiostomatales on storm-damaged R. melanophloeos trees in the Afromontane forests of South Africa. Five species were identified based on micro-morphological and molecular phylogenetic analyses. These included Ophiostoma stenoceras and four newly described taxa Sporothrix itsvo sp. nov., S. rapaneae sp. nov., S. uta sp. nov. and O. noisomeae sp. nov. Four of these are members of the S. schenckii-O. stenoceras complex (O. stenoceras, S. itsvo sp. nov., S. rapaneae sp. nov., S. uta sp. nov.) while O. noisomeae groups basal in the Ophiostomatales alongside the S. lignivora complex and Graphilbum. In addition to other taxa known from this host, the present study shows that there is a rich, yet still poorly explored, diversity of Ophiostomatales associated with R. melanophloeos in Afromontane forests. More taxa are likely to be discovered with increased research effort. These must be assessed in terms of pathogenicity towards this ecologically and economically important tree.

Novel ophiostomatalean fungi from galleries of Cyrtogenius africus (Scolytinae) infesting dying Euphorbia ingens

Euphorbia ingens trees have been dying in large numbers in the Limpopo Province of South Africa for approximately 15 years. The ambrosia beetle Cyrtogenius africus is often found infesting diseased and dying trees. The aim of this study was to identify the ophiostomatoid fungi occurring in the galleries of C. africus. Logs infested with this beetle were collected from the KwaZulu-Natal, Limpopo, Mpumalanga, and North West Provinces of South Africa. Fungi belonging to the Ophiostomatales were identified based on morphology and comparison of sequence data for the β-tubulin, ITS1-5.8S-ITS2 and LSU gene regions. A novel species of Ophiostoma and a novel genus in the Ophiostomatales were identified. Inoculation studies with these fungi produced lesions in the branches of healthy E. ingens trees.

Multigene phylogenies and morphological characterization of five new Ophiostoma spp. associated with spruce-infesting bark beetles in China

Ophiostoma spp. (Ophiostomatales, Ascomycota) are well-known fungi associated with bark beetles (Coleoptera: Scolytinae). Some of these are serious tree pathogens, while the majority is blue-stain agents of timber. In recent years, various bark beetle species have been attacking spruce forests in Qinghai province, China, causing significant damage. A preliminary survey was done to explore the diversity of the ophiostomatoid fungal associates of these beetles. The aims of the present study were to identify and characterize new Ophiostoma spp. associated with spruce-infesting bark beetles in Qinghai Province, and to resolve phylogenetic relationships of Ophiostoma spp. related to the Chinese isolates, using multigene phylogenetic analyses. Results obtained from four gene regions (ribosomal internal transcribed spacer regions, β-tubulin, calmodulin, translation elongation factor-1α) revealed five new Ophiostoma spp. from Qinghai. These included O. nitidus sp. nov., O. micans sp. nov., and O. qinghaiense sp. nov. in a newly defined O. piceae complex. The other two new species, O. poligraphi sp. nov. and O. shangrilae sp. nov., grouped in the O. brunneo-ciliatum complex. Based on DNA sequence and morphological comparisons, we also show that O. arduennense and O. torulosum are synonyms of O. distortum, while O. setosum is a synonym of O. cupulatum.

Ophiostomatoid fungi including two new fungal species associated with pine root-feeding beetles in northern Spain

Many bark beetles live in a symbiosis with ophiostomatoid fungi but very little is known regarding these fungi in Spain. In this study, we considered the fungi associated with nine bark beetle species and one weevil infesting two native tree species (Pinus sylvestris and Pinus nigra) and one non-native (Pinus radiata) in Cantabria (Northern Spain). This included examination of 239 bark beetles or their galleries. Isolations yielded a total of 110 cultures that included 11 fungal species (five species of Leptographium sensu lato including Leptographium absconditum sp. nov., five species of Ophiostoma sensu lato including Ophiostoma cantabriense sp. nov, and one species of Graphilbum). The most commonly encountered fungal associates of the bark beetles were Grosmannia olivacea, Leptographium procerum, and Ophiostoma canum. The aggressiveness of the collected fungal species was evaluated using inoculations on two-year-old P. radiata seedlings. Leptographium wingfieldii, Leptographium guttulatum, and Ophiostoma ips were the only species capable of causing significant lesions.

Panmixia defines the genetic diversity of a unique arthropod-dispersed fungus specific to Protea flowers

Knoxdaviesia proteae, a fungus specific to the floral structures of the iconic Cape Floral Kingdom plant, Protea repens, is dispersed by mites phoretic on beetles that pollinate these flowers. Although the vectors of K. proteae have been identified, little is known regarding its patterns of distribution. Seed bearing infructescences of P. repens were sampled from current and previous flowering seasons, from which K. proteae individuals were isolated and cultured. The genotypes of K. proteae isolates were determined using 12 microsatellite markers specific to this species. Genetic diversity indices showed a high level of similarity between K. proteae isolates from the two different infructescence age classes. The heterozygosity of the population was high (0.74 ± 0.04), and exceptional genotypic diversity was encountered (Ĝ = 97.87%). Population differentiation was negligible, owing to the numerous migrants between the infructescence age classes (N m = 47.83) and between P. repens trees (N m = 2.96). Parsimony analysis revealed interconnected genotypes, indicative of recombination and homoplasies, and the index of linkage disequilibrium confirmed that outcrossing is prevalent in K. proteae ([Formula: see text] = 0.0067; P = 0.132). The high diversity and panmixia in this population is likely a result of regular gene flow and an outcrossing reproductive strategy. The lack of genetic cohesion between individuals from a single P. repens tree suggests that K. proteae dispersal does not primarily occur over short distances via mites as hypothesized, but rather that long-distance dispersal by beetles plays an important part in the biology of these intriguing fungi.

Phylogeny and taxonomy of species in the Grosmannia serpens complex

Grosmannia serpens was first described from pine in Italy in 1936 and it has been recorded subsequently from many countries in both the northern and southern hemispheres. The fungus is vectored primarily by root-infesting bark beetles and has been reported to contribute to pine-root diseases in Italy and South Africa. The objective of this study was to consider the identity of a global collection of isolates not previously available and using DNA sequence-based comparisons not previously applied to most of these isolates. Phylogenetic analyses of the ITS2-LSU, actin, beta-tubulin, calmodulin and translation elongation factor-1 alpha sequences revealed that these morphologically similar isolates represent a complex of five cryptic species. Grosmannia serpens sensu stricto thus is redefined and comprises only isolates from Italy including the ex-type isolate. The ex-type isolate of Verticicladiella alacris was shown to be distinct from G. serpens, and a new holomorphic species, G. alacris, is described. The teleomorph state of G. alacris was obtained through mating studies in the laboratory, confirming that this species is heterothallic. Most of the available isolates, including those from South Africa, USA, France, Portugal and some from Spain, represent G. alacris. The remaining three taxa, known only in their anamorph states, are described as the new species Leptographium gibbsii for isolates from the UK, L. yamaokae for isolates from Japan and L. castellanum for isolates from Spain and the Dominican Republic.

Ophiostoma spp. associated with pine- and spruce-infesting bark beetles in Finland and Russia

The timber and pulp industries of Finland rely heavily on importations from Russia as source of raw timber. These imports raise the risk of accidentally importing forest pests and pathogens, especially bark beetles and their associated fungi, into Finland. Although ophiostomatoid fungi have previously been reported from Finland and Russia, the risks of accidentally moving these fungi has prompted a first survey to compare the diversity of conifer-infesting bark beetles and associated fungi from boreal forests on both sides of the Finnish-Russian border. The aim of the present study was to identify and characterise Ophiostoma species isolated in association with 11 bark beetle species infesting Pinus sylvestris and Picea abies during this survey in the eastern parts of Finland and neighbouring Russia. Fungal isolates were grouped based on morphology and representatives of each morphological group were subjected to DNA sequence comparisons of the internal transcribed spaced region (ITS1, 5.8S, ITS2) and β-tubulin gene region. A total of 15 species of Ophiostoma were identified, including seven known species, five new species, and three species for which the identity remains uncertain. In the O. piceae-complex we identified O. canum, O. floccosum, O. karelicum and O. rachisporum sp. nov., and related to these, some isolates belonging to the European clade of O. minus in the O. minus-complex. Ophiostoma bicolor and O. fuscum sp. nov. were identified in the O. ips-complex, while O. ainoae, O. brunneo-ciliatum, O. tapionis sp. nov. and O. pallidulum sp. nov. were shown to group close to, but not in a strict monophyletic lineage with species of the O. ips-complex. Together with a single O. abietinum-like isolate, the only species that grouped close to the Sporothrix schenckii- O. stenoceras complex, was O. saponiodorum sp. nov.

Sporothrix brunneoviolacea and Sporothrix dimorphospora, two new members of the Ophiostoma stenoceras-Sporothrix schenckii complex

Sporothrix inflata is a saprobic member of the Ophiostoma stenoceras-Sporothrix schenckii species complex, reported mainly from soil. Ophiostoma bragantinum, an ascomycete described from Brazil, has been proposed as its possible teleomorph. Previous studies revealed that Sporothrix inflata is phenotypically and genetically variable, suggesting the existence of cryptic species. During a continued survey on the biodiversity of microfungi from different countries, seven isolates morphologically similar to S. inflata were obtained from soil samples collected in Spain and USA. In this study their phenotypic features and phylogenetic relationships were assessed. DNA sequence data of two nuclear loci revealed that these isolates correspond to two unnamed clades in S. inflata s.l., one of which also included the type strain of Humicola dimorphospora, a species that traditionally has been considered a synonym of S. inflata. These two groups are proposed herein as Sporothrix brunneoviolacea sp. nov. and Sporothrix dimorphospora comb. nov. S. brunneoviolacea is characterized phenotypically by the production of a diffusible violet-brown pigment in culture and mostly globose, pigmented, lateral blastoconidia. On the other hand S. dimorphospora lacks diffusible pigments and shows mostly subglobose to obovoid pigmented lateral blastoconidia. In contrast to the type strain of S. inflata S. brunneoviolacea and S. dimorphospora assimilate raffinose. The phylogenetic analysis suggested that the proposed anamorph-teleomorph connection between S. inflata and O. bragantinum might not be correct.

Two new Ophiostoma species from Protea caffra in Zambia

The genus Ophiostoma (Ophiostomatales) has a global distribution and species are best known for their association with bark beetles (Curculionidae: Scolytinae) on conifers. An unusual assemblage of these fungi is closely associated with the African endemic plant genus Protea (Proteaceae). Protea-associated Ophiostoma species are ecologically atypical as they colonise the fruiting structures of various serotinous Protea species. Seven species have been described from this niche in South Africa. It has been speculated that novel species may be present in other African countries where these host plants also occur. This view was corroborated by recent collections of two unknown species from Protea caffra trees in Zambia. In the present study we evaluate the species delineation of these isolates using morphological comparisons with other Protea-associated species, differential growth studies and analyses of DNA sequence data for the β-tubulin and internal transcribed spacer (ITS1, 5.8S, ITS2) regions. As a result, the species O. protea-sedis sp. nov., and O. zambiensis sp. nov. are described here as new. This study brings the number of Protea-associated Ophiostoma species to nine and highlights the need for more inclusive surveys, including additional African countries and hosts, to elucidate species diversity in this uncharacteristic niche.