The Ophiostoma clavatum species complex: a newly defined group in the Ophiostomatales including three novel taxa

Soil-borne Ophiostomatales species (Sordariomycetes, Ascomycota) in beech, oak, pine, and spruce stands in Poland with descriptions of Sporothrixroztoczensis sp. nov., S.silvicola sp. nov., and S.tumida sp. nov

Ophiostomatales (Ascomycota) contains many species, most of which are associated with bark beetles. Some members of this order are plant or animal pathogens, while others colonize soil, different plant tissues, or even carpophores of some Basidiomycota. However, little is known about soil-inhabiting Ophiostomatales fungi. A survey of these fungi associated with soil under beech, oak, pine, and spruce stands in Poland yielded 623 isolates, representing 10 species: Heinzbutiniagrandicarpa, Leptographiumprocerum, L.radiaticola, Ophiostomapiliferum, O.quercus, Sporothrixbrunneoviolacea, S.dentifunda, S.eucastaneae, and two newly described taxa, namely Sporothrixroztoczensissp. nov. and S.silvicolasp. nov. In addition, isolates collected from fallen shoots of Pinussylvestris that were pruned by Tomicus sp. are described as Sporothrixtumidasp. nov. The new taxa were morphologically characterized and phylogenetically analyzed based on multi-loci sequence data (ITS, β-tubulin, calmodulin, and translation elongation factor 1-α genes). The Ophiostomatales species were especially abundant in soil under pine and oak stands. Leptographiumprocerum, S.silvicola, and S.roztoczensis were the most frequently isolated species from soil under pine stands, while S.brunneoviolacea was the most abundant in soil under oak stands. The results highlight that forest soil in Poland has a wide diversity of Ophiostomatales taxa, but further studies are required to uncover the molecular diversity and phylogenetic relationships of these fungi, as well as their roles in soil fungal communities.

Insight into the genomes of dominant yeast symbionts of European spruce bark beetle, Ips typographus

Spruce bark beetle Ips typographus can trigger outbreaks on spruce that results in significant losses in the forest industry. It has been suggested that symbiotic microorganisms inhabiting the gut of bark beetles facilitate the colonization of plant tissues as they play a role in the detoxification of plant secondary metabolites, degrade plant cell wall and ameliorate beetle's nutrition. In this study, we sequenced and functionally annotated the genomes of five yeasts Kuraishia molischiana, Cryptococcus sp., Nakazawaea ambrosiae, Ogataea ramenticola, and Wickerhamomyces bisporus isolated from the gut of Ips typographus. Genome analysis identified 5314, 7050, 5722, 5502, and 5784 protein coding genes from K. molischiana, Cryptococcus sp., N. ambrosiae, O. ramenticola, and W. bisporus, respectively. Protein-coding sequences were classified into biological processes, cellular and molecular function based on gene ontology terms enrichment. Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation was used to predict gene functions. All analyzed yeast genomes contain full pathways for the synthesis of essential amino acids and vitamin B6, which have nutritional importance to beetle. Furthermore, their genomes contain diverse gene families related to the detoxification processes. The prevalent superfamilies are aldo-keto reductase, ATP-binding cassette and the major facilitator transporters. The phylogenetic relationships of detoxification-related enzymes aldo-keto reductase, and cytochrome P450 monooxygenase, and ATP-binding cassette are presented. Genome annotations also revealed presence of genes active in lignocellulose degradation. In vitro analyses did not confirm enzymatic endolytic degradation of lignocellulose; however, all species can utilize and pectin and produce a large spectrum of exolytic enzymes attacking cellulose, chitin, and lipids.

Identification of ophiostomatalean fungi associated with Tomicus pilifer infesting Pinus koraiensis in Northeastern China

Ophiostomatalean fungi usually facilitate bark beetles to infest tree hosts and seriously endanger the health of coniferous forests. Tomicus pilifer Spessivtsev is a common endemic bark beetle in Asia and primarily threatens Pinus koraiensis. Tomicus species have similar morphology; however, they can be differentiated by their genetic characteristics through phylogenetic analyses. To date, the 28S rDNA sequence of T. pilifer and the diversity of ophiostomatalean fungi associated with T. pilifer have not been reported. In this study, we aimed to clarify the taxonomic status of T. pilifer and identify ophiostomatalean fungi associated with T. pilifer infesting P. koraiensis in northeastern China. In total, 315 ophiostomatalean fungal strains were isolated from 62 adults of T. pilifer and 220 tissue samples from T. pilifer galleries in Jilin Province. Thirty-five representative strains were further identified by comparing their morphological and physiological characteristics and conducting the phylogenetic analysis of ITS, ITS2-LSU, TUB2, and TEF1-α. We identified nine species of ophiostomatalean fungi belonging to four genera, which included six novel species (Ceratocystiopsis changbaiensis sp. nov., Leptographium linjiangense sp. nov., Leptographium qieshaoense sp. nov., Ophiostoma piliferi sp. nov., Ophiostoma tonghuaense sp. nov., and Ophiostoma yaluense sp. nov.), two previously described species (Graphilbum interstitiale and Ophiostoma fuscum), and one undefined specie (Ceratocystiopsis sp. 1). To the best of our knowledge, this is the first report of G. interstitiale and O. fuscum in China and the fungal diversity of ophiostomatalean in T. pilifer. The dominant species were O. piliferi and L. qieshaoense, representing 39.37% and 35.87% of the isolates, respectively. The results of this study provide valuable information on the symbiotic relationship between bark beetles and ophiostomatalean fungi.

Diversity of Ophiostomatoid Fungi Associated with Dendroctonus armandi Infesting Pinus armandii in Western China

Pinus armandii (P. armandii) is extensively abundant in western China and, as a pioneer tree, and prominently influences local ecology. However, pine forests in this region have been significantly damaged by Dendroctonus armandi (D. armandi) infestations, in close association with ophiostomatoid fungi. This study aimed to identify the diversity of ophiostomatoid fungi associated with D. armandi infesting P. armandii in western China. A total of 695 ophiostomatoid fungal strains were isolated from 1040 tissue pieces from D. armandi galleries and 89 adult beetles at four sites. In this study, based on multiloci DNA sequence data, as well as morphological and physiological characteristics, seven species belonging to five genera were identified including three known species, Esteyea vermicola, Graphium pseudormiticum and L. wushanense, two novel taxa, Graphilbum parakesiyea and Ophiostoma shennongense, and an unidentified Ophiostoma sp. 1. A neotype of Leptographium qinlingense. Ophiostoma shennongense was the dominant taxon (78.99%) in the ophiostomatoid community. This study provides a valuable scientific theoretical basis for the occurrence and management of D. armandi in the future.

Fungal Communities Vectored by Ips sexdentatus in Declining Pinus sylvestris in Ukraine: Focus on Occurrence and Pathogenicity of Ophiostomatoid Species

Drought-induced stress and attacks by bark beetle Ips sexdentatus currently result in a massive dieback of Pinus sylvestris in eastern Ukraine. Limited and fragmented knowledge is available on fungi vectored by the beetle and their roles in tree dieback. The aim was to investigate the fungal community vectored by I. sexdentatus and to test the pathogenicity of potentially aggressive species to P. sylvestris. Analysis of the fungal community was accomplished by combining different methods using insect, plant, and fungal material. The material consisted of 576 beetles and 96 infested wood samples collected from six sample plots within a 300 km radius in eastern Ukraine and subjected to fungal isolations and (beetles only) direct sequencing of ITS rDNA. Pathogenicity tests were undertaken by artificially inoculating three-to-four-year-old pine saplings with fungi. For the vector test, pine logs were exposed to pre-inoculated beetles. In all, 56 fungal taxa were detected, 8 exclusively by isolation, and 13 exclusively by direct sequencing. Those included nine ophiostomatoids, five of which are newly reported as I. sexdentatus associates. Two ophiostomatoid fungi, which exhibited the highest pathogenicity, causing 100% dieback and mortality, represented genera Graphium and Leptographium. Exposure of logs to beetles resulted in ophiostomatoid infections. In conclusion, the study revealed numerous I. sexdentatus-vectored fungi, several of which include aggressive tree pathogens.

Ophiostomatoid species associated with pine trees (Pinus spp.) infested by Cryphaluspiceae from eastern China, including five new species

Cryphaluspiceae attacks various economically important conifers. Similar to other bark beetles, Cr.piceae plays a role as a vector for an assortment of fungi and nematodes. Previously, several ophiostomatoid fungi were isolated from Cr.piceae in Poland and Japan. In the present study, we explored the diversity of ophiostomatoid fungi associated with Cr.piceae infesting pines in the Shandong Province of China. We isolated ophiostomatoid fungi from both galleries and beetles collected from our study sites. These fungal isolates were identified using both molecular and morphological data. In this study, we recovered 175 isolates of ophiostomatoid fungi representing seven species. Ophiostomaips was the most frequently isolated species. Molecular and morphological data indicated that five ophiostomatoid fungal species recovered were previously undescribed. Thus, we proposed these five novel species as Ceratocystiopsisyantaiensis, C.weihaiensis, Graphilbumtranslucens, Gr.niveum, and Sporothrixvillosa. These new ophiostomatoid fungi add to the increasing number of fungi known from China, and this evidence suggests that numerous novel taxa are awaiting discovery in other forests of China.

Ophiostomatoid fungi associated with mites phoretic on bark beetles in Qinghai, China

Bark beetle galleries are complex ecosystems where many microbes and other arthropods co-exist with the beetles. Fungi isolated from these galleries are often referred to as ‘beetle associates’, but the nature of these associations are poorly understood. The possibility that many of these fungi might in fact be mite associates is often overlooked. Several recent studies explored the diversity of fungi from conifer-infesting bark beetles and their galleries in China, but only one study considered phoretic mites and their fungi from conifer-infesting bark beetles in Yunnan, southwestern China. We studied the mites and fungi from galleries of four spruce-infesting bark beetle species in the high altitude forests of Qinghai province, western China. Mites were identified based on morphological characteristics, and fungi based on DNA sequences of four gene regions. In total, 173 mite individuals were collected belonging to 18 species in 11 genera. A total of 135 fungal isolates were obtained from the mites, representing 14 taxa from the Ophiostomatales. The most frequently isolated fungus was Ophiostoma nitidum, which represented 23.5% of the total isolates. More fungal species were found from fewer mites and bark beetle species than from the study in Yunnan. Although we could not elucidate the exact nature of interactions between mites and their fungi, our results re-enforce that these organisms should not be ignored in pest risk assessments of bark beetles, that often focus only on the beetles and their fungi. Three new species are described: Grosmannia zekuensis, O. manchongi, and O. kunlunense spp. nov., and our data revealed that O. typographi, recently described from China, is a synonym of O. ainoae.

Ophiostomatoid fungi associated with Ips subelongatus, including eight new species from northeastern China

Ips subelongatus is a major pest that infects larch plantations over large areas of northern and northeastern China. Ips species are closely associated with ophiostomatoid fungi that are morphologically well-adapted for dispersal by beetles. These associations result in important threat for coniferous forests worldwide. The aim of this study was to characterize the ophiostomatoid communities associated with I. subelongatus infesting Larix species and sympatric Pinus sylvestris var. mongolica in northeastern China forests. Morphological and multilocus phylogenetic approaches (based on six markers: ITS, LSU, 60S, β-tubulin, EF-1α, and CAL gene regions) allowed identifying 14 species of four genera (Ceratocystiopsis, Endoconidiophora, Leptographium and Ophiostoma). Eight species are showed to be new to science. Most strains resided in two Ophiostoma species complexes, viz. the O. clavatum and the O. ips complexes, all together accounting for 76.8% of all isolates. Ophiostoma hongxingense sp. nov., O. peniculi sp. nov., and O. subelongati sp. nov. (O. clavatum complex) and O. pseudobicolor sp. nov. (O. ips complex) were the four dominant species. The ophiostomatoid communities associated with larch bark beetles, I. cembrae and I. subelongatus, in Europe and Asia, China and Japan, also were compared. These comparisons showed distinct, specific assemblage patterns.

Four new Ophiostoma species associated with conifer- and hardwood-infesting bark and ambrosia beetles from the Czech Republic and Poland

Fungi under the order Ophiostomatales (Ascomycota) are known to associate with various species of bark beetles (Coleoptera: Curculionidae: Scolytinae). In addition this group of fungi contains many taxa that can impart blue-stain on sapwood and some are important tree pathogens. A recent survey that focussed on the diversity of the Ophiostomatales in the forest ecosystems of the Czech Republic and Poland uncovered four putative new species. Phylogenetic analyses of four gene regions (ITS1-5.8S-ITS2 region, ß-tubulin, calmodulin, and translation elongation factor 1-α) indicated that these four species are members of the genus Ophiostoma. All four newly described species can be distinguished from each other and from closely related species based on DNA sequence comparisons, morphological characters, growth rates, and their insect associations. Based on this study four new taxa can be circumscribed and the following names are provided: Ophiostoma pityokteinis sp. nov., Ophiostoma rufum sp. nov., Ophiostoma solheimii sp. nov., and Ophiostoma taphrorychi sp. nov. O. rufum sp. nov. is a member of the Ophiostoma piceae species complex, while O. pityokteinis sp. nov. resides in a discrete lineage within Ophiostoma s. stricto. O. taphrorychi sp. nov. together with O. distortum formed a well-supported clade in Ophiostoma s. stricto close to O. pityokteinis sp. nov. O. solheimii sp. nov. groups within a currently undefined lineage A, which also includes Ophiostoma grandicarpum and Ophiostoma microsporum. This study highlights the need for more intensive surveys that should include additional countries of Central Europe, insect vectors and host tree species in order to elucidate Ophiostoma species diversity in this region.

Differential patterns of ophiostomatoid fungal communities associated with three sympatric Tomicus species infesting pines in south-western China, with a description of four new species

Bark beetles and their associated fungi, which cause forest decline and sometimes high mortality in large areas around the world, are of increasing concern in terms of forest health. Three Tomicus spp. (T.brevipilosus, T.minor and T.yunnanensis) infect branches and trunks of Pinusyunnanensis and P.kesiya in Yunnan Province, in south-western China. Tomicus spp. are well known as vectors of ophiostomatoid fungi and their co-occurrence could result in serious ecological and economic impact on local forest ecosystems. Nonetheless, knowledge about their diversity, ecology, including pathogenicity and potential economic importance is still quite rudimentary. Therefore, an extensive survey of ophiostomatoid fungi associated with these Tomicus species infesting P.yunnanensis and P.kesiya was carried out in Yunnan. Seven hundred and seventy-two strains of ophiostomatoid fungi were isolated from the adult beetles and their galleries. The strains were identified based on comparisons of multiple DNA sequences, including the nuclear ribosomal large subunit (LSU) region, the internal transcribed spacer regions 1 and 2, together with the intervening 5.8S gene (ITS) and the partial genes of β-tubulin (TUB2), elongation factor 1α (TEF1-α) and calmodulin (CAL). Phylogenetic analyses were performed using maximum parsimony (MP) as well as maximum likelihood (ML). Combinations of culture features, morphological characters and temperature-dependent growth rates were also employed for species identification. Eleven species belonging to five genera were identified. These included six known species, Esteyavermicola, Leptographiumyunnanense, Ophiostomabrevipilosi, O.canum, O.minus and O.tingens and four novel taxa, described as Graphilbumanningense, O.aggregatum, Sporothrixpseudoabietina and S.macroconidia. A residual strain was left unidentified as Ophiostoma sp. 1. The overall ophiostomatoid community was by far dominated by three species, representing 87.3% of the total isolates; in decreasing order, these were O.canum, O.brevipilosi and O.minus. Furthermore, the ophiostomatoid community of each beetle, although harbouring a diversity of ophiostomatoid species, was differentially dominated by a single fungal species; Ophiostomacanum was preferentially associated with and dominated the ophiostomatoid community of T.minor, whereas O.brevipilosi and O.minus were exclusively associated with and dominated the ophiostomatoid communities of T.brevipilosus and T.yunnanensis, respectively. Eight additional species, representing the remaining 12.7% of the total isolates, were marginal or sporadic. These results suggested that sympatric Tomicus populations are dominated by distinct species showing some level of specificity or even exclusivity.

Ophiostomatoid fungi associated with the spruce bark beetle Ips typographus, including 11 new species from China

Ips typographus (Coleoptera, Scolytinae) is a spruce-infesting bark beetle that occurs throughout Europe and Asia. The beetle can cause considerable damage, especially when colonized trees are stressed and beetle populations increase. Although some studies have shown that populations of I. typographus in Europe, China and Japan are genetically distinct, these populations are biologically similar, including a strong association with ophiostomatoid fungi. To date, only two Leptographium spp. have been reported from the beetle in China, while 40 species have been reported from Europe and 13 from Japan. The aims of this study were to identify the ophiostomatoid fungal associates of I. typographus in north-eastern China, and to determine whether the fungal assemblages reflect the different geographical populations of the beetle. Field surveys in Jilin and Heilongjiang provinces yielded a total of 1 046 fungal isolates from 145 beetles and 178 galleries. Isolates were grouped based on morphology and representatives of each group were identified using DNA sequences of the ribosomal LSU, ITS, β-tubulin, calmodulin and elongation factor 1-α gene regions. A total of 23 species of ophiostomatoid fungi were identified, including 12 previously described species and 11 novel species, all of which are described here. The dominant species were Ophiostoma bicolor, Leptographium taigense and Grosmannia piceiperda D, representing 40.5 %, 27.8 % and 17.8 % of the isolates, respectively. Comparisons of species from China, Europe and Japan are complicated by the fact that some of the European and all the Japanese species were identified based only on morphology. However, assuming that those identifications are correct, five species were shared between Europe, Japan and China, two species were shared between China and Japan, five between Europe and China, and two between Europe and Japan. Consequently, Ips typographus populations in these different geographic areas have different fungal assemblages, suggesting that the majority of these beetle-associations are promiscuous. The results also suggested that the symbionts of the bark beetle do not reflect the population structures of the beetle. The use of fungal symbiont assemblages to infer population structures and invasion history of its vectors should thus be interpreted with circumspection.

Cadophora margaritata sp. nov. and other fungi associated with the longhorn beetles Anoplophora glabripennis and Saperda carcharias in Finland

Symbiosis with microbes is crucial for survival and development of wood-inhabiting longhorn beetles (Coleoptera: Cerambycidae). Thus, knowledge of the endemic fungal associates of insects would facilitate risk assessment in cases where a new invasive pest occupies the same ecological niche. However, the diversity of fungi associated with insects remains poorly understood. The aim of this study was to investigate fungi associated with the native large poplar longhorn beetle (Saperda carcharias) and the recently introduced Asian longhorn beetle (Anoplophora glabripennis) infesting hardwood trees in Finland. We studied the cultivable fungal associates obtained from Populus tremula colonised by S. carcharias, and Betula pendula and Salix caprea infested by A. glabripennis, and compared these to the samples collected from intact wood material. This study detected a number of plant pathogenic and saprotrophic fungi, and species with known potential for enzymatic degradation of wood components. Phylogenetic analyses of the most commonly encountered fungi isolated from the longhorn beetles revealed an association with fungi residing in the Cadophora-Mollisia species complex. A commonly encountered fungus was Cadophora spadicis, a recently described fungus associated with wood-decay. In addition, a novel species of Cadophora, for which the name Cadophora margaritata sp. nov. is provided, was isolated from the colonised wood.

Ophiostomatoid fungi associated with conifer-infesting beetles and their phoretic mites in Yunnan, China

The Ophiostomatales is an Ascomycete order of fungi that accommodates several tree pathogens and many species that degrade wood. These fungi are commonly vectored by Scolytine bark and ambrosia beetles. In recent years it has also been shown that hyperphoretic mites on these beetles can vector some Ophiostomatales. Little is known regarding the Ophiostomatales in China and we have consequently explored the diversity of these fungi associated with conifer-infesting beetles and mites in Yunnan province. Galleries and beetles were collected for 17 beetle species, while 13 mite species were obtained from six of these beetle species. Collectively, 340 fungal isolates were obtained, 45 from beetles, 184 from mites, 56 from galleries and 55 isolates where the specific niche was not clear. DNA sequences for five gene regions (ITS, LSU, BT, EF, and CAL) were determined for fungal isolates representing different morphological groups. Phylogenetic analyses confirmed the presence of 19 fungal taxa, including five novel species described here as Ophiostoma acarorumsp. nov., Ophiostoma brevipilosisp. nov., Graphilbum kesiyaesp. nov., Graphilbum puerensesp. nov., and Leptographium ningerensesp. nov.Ophiostoma ips was the most frequently isolated species, representing approximately 31% of all isolates. Six of 19 taxa were present on mites, beetles and in the galleries of the beetles, while three species were found on mites and galleries. Two species were found only on mites and one species only on a beetle. Although the numbers of beetles and mites were insufficient to provide statistical inferences, this study confirmed that mites are important vectors of the Ophiostomatales in China. We hypothesize that these mites are most likely responsible for horizontal transfer of fungal species between galleries of different beetle species. The fact that half of the fungal species found were new to science, suggests that the forests of east Asia include many undescribed Ophiostomatales yet to be discovered.