Micromelanconis kaihuiae gen. et sp. nov., a new diaporthalean fungus from Chinese chestnut branches in southern China

Melanconis-like fungi are distributed in several families of Diaporthales, mainly Juglanconidaceae, Melanconidaceae, Melanconiellaceae and Pseudomelanconidaceae. A new Melanconis-like genus of Pseudomelanconidaceae was discovered on branches of Chinese chestnut (Castanea mollissima) in southern China, which was confirmed by both morphology and phylogenetic analysis of combined ITS, LSU, tef1a and rpb2 sequences. The new genus Micromelanconis is characterized by two types of conidia from natural substrate and manual media of PDA, respectively. Conidia from Chinese chestnut branches are pale brown, ellipsoid, multiguttulate, aseptate with hyaline sheath. While conidia from PDA plates are pale brown, long dumbbell-shaped, narrow at the middle and wide at both ends, multiguttulate, aseptate, and also with hyaline sheath. All Pseudomelanconidaceae species were only reported on tree branches in China until now. More interesting taxa may be discovered if detailed surveys on tree-inhabiting fungi are carried out in East Asia in the future.

New species and records of Diaporthe from Jiangxi Province, China

Diaporthe species have often been reported as important plant pathogens, saprobes and endophytes on a wide range of plant hosts. Although several Diaporthe species have been recorded, little is known about species able to infect forest trees in Jiangxi Province. Hence, extensive surveys were recently conducted in Jiangxi Province, China. A total of 24 isolates were identified and analysed using comparisons of DNA sequence data for the nuclear ribosomal internal transcribed spacer (ITS), calmodulin (cal), histone H3 (his3), partial translation elongation factor-1α (tef1) and β-tubulin (tub2) gene regions, as well as their morphological features. Results revealed five novel taxa, D. bauhiniae, D. ganzhouensis, D. schimae, D. verniciicola, D. xunwuensis spp. nov. and three known species, D. apiculatum, D. citri and D. multigutullata.

Fungal diversity notes 1387-1511: taxonomic and phylogenetic contributions on genera and species of fungal taxa

This article is the 13th contribution in the Fungal Diversity Notes series, wherein 125 taxa from four phyla, ten classes, 31 orders, 69 families, 92 genera and three genera incertae sedis are treated, demonstrating worldwide and geographic distribution. Fungal taxa described and illustrated in the present study include three new genera, 69 new species, one new combination, one reference specimen and 51 new records on new hosts and new geographical distributions. Three new genera, Cylindrotorula (Torulaceae), Scolecoleotia (Leotiales genus incertae sedis) and Xenovaginatispora (Lindomycetaceae) are introduced based on distinct phylogenetic lineages and unique morphologies. Newly described species are Aspergillus lannaensis, Cercophora dulciaquae, Cladophialophora aquatica, Coprinellus punjabensis, Cortinarius alutarius, C. mammillatus, C. quercoflocculosus, Coryneum fagi, Cruentomycena uttarakhandina, Cryptocoryneum rosae, Cyathus uniperidiolus, Cylindrotorula indica, Diaporthe chamaeropicola, Didymella azollae, Diplodia alanphillipsii, Dothiora coronicola, Efibula rodriguezarmasiae, Erysiphe salicicola, Fusarium queenslandicum, Geastrum gorgonicum, G. hansagiense, Helicosporium sexualis, Helminthosporium chiangraiensis, Hongkongmyces kokensis, Hydrophilomyces hydraenae, Hygrocybe boertmannii, Hyphoderma australosetigerum, Hyphodontia yunnanensis, Khaleijomyces umikazeana, Laboulbenia divisa, Laboulbenia triarthronis, Laccaria populina, Lactarius pallidozonarius, Lepidosphaeria strobelii, Longipedicellata megafusiformis, Lophiotrema lincangensis, Marasmius benghalensis, M. jinfoshanensis, M. subtropicus, Mariannaea camelliae, Melanographium smilaxii, Microbotryum polycnemoides, Mimeomyces digitatus, Minutisphaera thailandensis, Mortierella solitaria, Mucor harpali, Nigrograna jinghongensis, Odontia huanrenensis, O. parvispina, Paraconiothyrium ajrekarii, Parafuscosporella niloticus, Phaeocytostroma yomensis, Phaeoisaria synnematicus, Phanerochaete hainanensis, Pleopunctum thailandicum, Pleurotheciella dimorphospora, Pseudochaetosphaeronema chiangraiense, Pseudodactylaria albicolonia, Rhexoacrodictys nigrospora, Russula paravioleipes, Scolecoleotia eriocamporesi, Seriascoma honghense, Synandromyces makranczyi, Thyridaria aureobrunnea, Torula lancangjiangensis, Tubeufia longihelicospora, Wicklowia fusiformispora, Xenovaginatispora phichaiensis and Xylaria apiospora. One new combination, Pseudobactrodesmium stilboideus is proposed. A reference specimen of Comoclathris permunda is designated. New host or distribution records are provided for Acrocalymma fici, Aliquandostipite khaoyaiensis, Camarosporidiella laburni, Canalisporium caribense, Chaetoscutula juniperi, Chlorophyllum demangei, C. globosum, C. hortense, Cladophialophora abundans, Dendryphion hydei, Diaporthe foeniculina, D. pseudophoenicicola, D. pyracanthae, Dictyosporium pandanicola, Dyfrolomyces distoseptatus, Ernakulamia tanakae, Eutypa flavovirens, E. lata, Favolus septatus, Fusarium atrovinosum, F. clavum, Helicosporium luteosporum, Hermatomyces nabanheensis, Hermatomyces sphaericoides, Longipedicellata aquatica, Lophiostoma caudata, L. clematidis-vitalbae, Lophiotrema hydei, L. neoarundinaria, Marasmiellus palmivorus, Megacapitula villosa, Micropsalliota globocystis, M. gracilis, Montagnula thailandica, Neohelicosporium irregulare, N. parisporum, Paradictyoarthrinium diffractum, Phaeoisaria aquatica, Poaceascoma taiwanense, Saproamanita manicata, Spegazzinia camelliae, Submersispora variabilis, Thyronectria caudata, T. mackenziei, Tubeufia chiangmaiensis, T. roseohelicospora, Vaginatispora nypae, Wicklowia submersa, Xanthagaricus necopinatus and Xylaria haemorrhoidalis. The data presented herein are based on morphological examination of fresh specimens, coupled with analysis of phylogenetic sequence data to better integrate taxa into appropriate taxonomic ranks and infer their evolutionary relationships.

Tree inhabiting gnomoniaceous species from China, with Cryphogonomonia gen. nov. proposed

Species of Gnomoniaceae are commonly associated with leaf spot diseases of a wide range of plant hosts worldwide. During our investigation of fungi associated with tree diseases in China, several gnomoniaceous isolates were recovered from symptomatic branches and leaves on different woody plants in the Fagaceae, Pinaceae, and Salicaceae families. These isolates were studied by applying a polyphasic approach including morphological, cultural data, and phylogenetic analyses of partial ITS, LSU, tef1, rpb2 and tub2 gene sequences. As a result, three species were identified with characters fitting into the family Gnomoniaceae. One of these species is described herein as Cryphognomonia pini gen. et sp. nov., characterized by developed pseudostromata and ascospores with obvious hyaline sheath; Gnomoniopsis xunwuensis sp. nov. is illustrated showing sympodially branched conidiophore, oval or fusiform conidia; and one known species, Plagiostoma populinum. The current study improves the understanding of gnomoniaceous species causing diebacks and leaf spot on ecological and economic forest trees.

Gnomoniopsis chinensis (Gnomoniaceae, Diaporthales), a new fungus causing canker of Chinese chestnut in Hebei Province, China

Chinese chestnut (Castaneamollissima) is an important crop tree species in China. However, branch canker and fruit rot are two kinds of severe diseases, which weaken the host and decrease chestnut production. During our investigations into chestnut diseases in China, several fungi have been confirmed as casual agents in previous studies, namely Aurantiosacculuscastaneae, Cryphonectrianeoparasitica, Cry.parasitica, Endothiachinensis and Gnomoniopsisdaii. In this study, a new canker pathogen is introduced based on morphology, phylogeny and pathogenicity. Typical Gnomoniopsis canker sign of wide, orange tendrils emerging from hosts’ glaucous lenticels were obvious on the diseased trees in the field. Symptomatic branches or bark on stems from different chestnut plantations were sampled and isolated, then strains were identified by comparisons of DNA sequence data for the nuclear ribosomal internal transcribed spacer (ITS), partial translation elongation factor-1α (tef1) and β-tubulin (tub2) gene regions as well as morphological features. As a result, these strains appeared different from any known Gnomoniopsis species. Hence, we propose a novel species named Gnomoniopsischinensis. Pathogenicity was further tested using the ex-type strain (CFCC 52286) and another strain (CFCC 52288) on both detached branches and 3-year-old chestnut seedlings. The inoculation results showed that Gnomoniopsischinensis is mildly pathogenic to Chinese chestnut. However, further studies are required to confirm its pathogenicity to the other cultivated Castanea species in America, Europe and Japan.

Three new Diaporthe species from Shaanxi Province, China

Diaporthe species (Sordariomycetes, Diaporthales) are often reported as important plant pathogens, saprobes and endophytes on a wide range of plant hosts. In this study, Diaporthe specimens were collected from symptomatic twigs and branches at the Huoditang Forest Farm in Shaanxi Province, China. Identification was done using a combination of morphology and comparison of DNA sequence data of the nuclear ribosomal internal transcribed spacer (ITS), calmodulin (cal), histone H3 (his3), partial translation elongation factor-1α (tef1) and β-tubulin (tub2) gene regions. Three new Diaporthe species are proposed: D.albosinensis, D.coryli and D.shaanxiensis. All species are illustrated and their morphology and phylogenetic relationships with other Diaporthe species are discussed.

Identification of six Cytospora species on Chinese chestnut in China

Chinese chestnut (Castanea mollissima) is an important crop tree species in China. In the present study, Cytospora specimens were collected from Chinese chestnut trees and identified using molecular data of combined ITS, LSU, ACT and RPB2 loci, as well as morphological features. As a result, two new Cytospora species and four new host records were confirmed, viz. C. kuanchengensis sp. nov., C. xinglongensis sp. nov., C. ceratospermopsis, C. leucostoma, C. myrtagena and C. schulzeri.

Taxonomy of two synnematal fungal species from Rhus chinensis, with Flavignomonia gen. nov. described

Rhuschinensis represents a commercially and ecologically important tree species in China, but suffers from canker diseases in Jiangxi Province. Synnemata, pycnidia and ascomata were discovered on cankered tissues. Strains were obtained from single ascospore or conidium within the fruiting bodies and identified based on morphological comparison and the phylogenetic analyses of partial ITS, LSU, tef1 and rpb2 gene sequences. As a result, two species were confirmed to represent two kinds of synnemata. One of these species is described herein as Flavignomoniarhoigenagen. et sp. nov.; and Synnemasporellaaculeans is illustrated showing ascomata, pycnidia and synnemata. Flavignomonia is distinguished from Synnemasporella by the colour of the synnematal tips. Additionally, Flavignomonia can be distinguished from the other gnomoniaceous genera by the formation of synnemata.

Nectria-related fungi causing dieback and canker diseases in China, with Neothyronectriacitri sp. nov. described

To clarify phylogenetic relationships amongst Nectria, Neothyronectria and Thyronectria in Nectriaceae, we examined detailed morphological characters and performed phylogenetic analyses of a concatenated dataset, based on the ITS, LSU, tef1 and tub2 DNA sequences of fungal specimens in China. Four species of nectria-related fungi were identified, i.e. Nectriadematiosa, N.pseudotrichia, Neothyronectriacitri and Thyronectriapinicola. The newly described species, Neothyronectriacitri, is characterised by its ascomatal wall with bright yellow scurf, unitunicate asci, each with 4-spored and ascospores allantoid to short-cylindrical, uniseriate, muriform, hyaline to slightly yellowish-brown. This species has affinities with other one known species of Neothyronectria and can be distinguished by molecular data.

Morphology and phylogeny reveal two novel Coryneum species from China

Coryneum is currently the sole genus of Coryneaceae in Diaporthales, distinguished from other diaporthalean genera by transversely distoseptate brown conidia. However, Coryneum species are presently difficult to identify because of variability and overlap of morphological characters and the lack of sequence data for most described species. During fungal collection trips in China, 13 Coryneum isolates were obtained from cankered branches of Ilex and Quercus. Morphological and phylogenetic analyses (ITS, LSU, TEF1-α and RPB2) revealed that these strains belong to two new species (viz. Coryneumilicissp. nov. and C.songshanensesp. nov.), and three known species, C.gigasporum, C.sinense, and C.suttonii. Coryneumilicis has larger conidia and more distosepta than most Coryneum species. Coryneumsongshanense was similar to C.sinense from the same host genus, Quercus, in conidial length, but distinct in conidial width and by molecular data.

Re-collection of Dermea prunus in China, with a description of D. chinensis sp. nov

Dermea was protected against its synonym, Foveostroma, due to its well-circumscribed generic concept and more frequent use. We describe and illustrate Dermeachinensissp. nov. based on its morphological characteristics and a molecular analysis of the internal transcribed spacer (ITS) and large subunit (LSU) sequence data. Dermeachinensis is isolated from Betulaalbosinensis with sexual and asexual morphs and can be distinguished from D.molliuscula on Betula trees by its aseptate and wider ascospores. The connection between the two morphs is proved based on sequence data. Here, we describe the asexual morph of D.pruni for the first time based on morphological and molecular data from the same host and country of origin, and compare it with other species of Prunus.

Species of Dendrostoma (Erythrogloeaceae, Diaporthales) associated with chestnut and oak canker diseases in China

Dendrostoma was recently proposed in Erythrogloeaceae (Diaporthales, Sordariomycetes), with all known members recorded as being plant pathogenic on economically important tree hosts. During our collections of Dendrostoma species in China, mild to severe canker symptoms were observed on sweet chestnut (Castaneamollissima) and oak (Quercus spp.) trees. Dead and dying plant tissues exhibiting Dendrostoma canker symptoms were sampled for fungal isolation. A total of 37 Dendrostoma isolates were obtained and analysed using morphological characteristics and molecular data (ITS, LSU, RPB2, TEF1-α). Based on these data, 10 novel clades could be distinguished, which also proved to represent morphologically distinct species described here as Dendrostomaaurorae, D.castaneae, D.castaneicola, D.chinense, D.dispersum, D. parasiticum, D.qinlingense, D.quercus, D.shaanxiense and D.shandongense spp. nov. A key to species of the genus is also provided.

High diversity of Diaporthe species associated with dieback diseases in China, with twelve new species described

Diaporthe species have often been reported as important plant pathogens, saprobes and endophytes on a wide range of plant hosts. Although several Diaporthe species have been recorded in China, little is known about species able to infect forest trees. Therefore, extensive surveys were recently conducted in Beijing, Heilongjiang, Jiangsu, Jiangxi, Shaanxi and Zhejiang Provinces. The current results emphasised on 15 species from 42 representative isolates involving 16 host genera using comparisons of DNA sequence data for the nuclear ribosomal internal transcribed spacer (ITS), calmodulin (cal), histone H3 (his3), partial translation elongation factor-1α (tef1) and β-tubulin (tub2) gene regions, as well as their morphological features. Three known species, D.biguttulata, D.eres and D.unshiuensis, were identified. In addition, twelve novel taxa were collected and are described as D.acerigena, D.alangii, D.betulina, D.caryae, D.cercidis, D.chensiensis, D.cinnamomi, D.conica, D.fraxinicola, D.kadsurae, D.padina and D.ukurunduensis. The current study improves the understanding of species causing diebacks on ecological and economic forest trees and provides useful information for the effective disease management of these hosts in China.

Arthrinium species associated with bamboo and reed plants in China

Arthrinium species are presently recognised based on a combination of morphological characteristics and internal transcribed spacer (ITS) sequence data. In the present study fresh Arthrinium specimens from bamboo and reed plants were collected in China. Morphological comparison and phylogenetic analyses were subsequently performed for species identification. From the results obtained two new species, Arthrinium gaoyouense and A. qinlingense are proposed, and three known species, Arthrinium arundinis, A. paraphaeospermum and A. yunnanum are identified based on morphological characteristics from the host and published DNA sequence data.

Comparative transcriptome analysis and identification of candidate effectors in two related rust species (Gymnosporangium yamadae and Gymnosporangium asiaticum)

BACKGROUND

Rust fungi constitute the largest group of plant fungal pathogens. However, a paucity of data, including genomic sequences, transcriptome sequences, and associated molecular markers, hinders the development of inhibitory compounds and prevents their analysis from an evolutionary perspective. Gymnosporangium yamadae and G. asiaticum are two closely related rust fungal species, which are ecologically and economically important pathogens that cause apple rust and pear rust, respectively, proved to be devastating to orchards. In this study, we investigated the transcriptomes of these two Gymnosporangium species during the telial stage of their lifecycles. The aim of this study was to understand the evolutionary patterns of these two related fungi and to identify genes that developed by selection.

RESULTS

The transcriptomes of G. yamadae and G. asiaticum were generated from a mixture of RNA from three biological replicates of each species. We obtained 49,318 and 54,742 transcripts, with N50 values of 1957 and 1664, for G. yamadae and G. asiaticum, respectively. We also identified a repertoire of candidate effectors and other gene families associated with pathogenicity. A total of 4947 pairs of putative orthologues between the two species were identified. Estimation of the non-synonymous/synonymous substitution rate ratios for these orthologues identified 116 pairs with Ka/Ks values greater than1 that are under positive selection and 170 pairs with Ka/Ks values of 1 that are under neutral selection, whereas the remaining 4661 genes are subjected to purifying selection. We estimate that the divergence time between the two species is approximately 5.2 Mya.

CONCLUSION

This study constitutes a de novo assembly and comparative analysis between the transcriptomes of the two rust species G. yamadae and G. asiaticum. The results identified several orthologous genes, and many expressed genes were identified by annotation. Our analysis of Ka/Ks ratios identified orthologous genes subjected to positive or purifying selection. An evolutionary analysis of these two species provided a relatively precise divergence time. Overall, the information obtained in this study increases the genetic resources available for research on the genetic diversity of the Gymnosporangium genus.

Integrating a Numerical Taxonomic Method and Molecular Phylogeny for Species Delimitation of Melampsora Species (Melampsoraceae, Pucciniales) on Willows in China

The species in genus Melampsora are the causal agents of leaf rust diseases on willows in natural habitats and plantations. However, the classification and recognition of species diversity are challenging because morphological characteristics are scant and morphological variation in Melampsora on willows has not been thoroughly evaluated. Thus, the taxonomy of Melampsora species on willows remains confused, especially in China where 31 species were reported based on either European or Japanese taxonomic systems. To clarify the species boundaries of Melampsora species on willows in China, we tested two approaches for species delimitation inferred from morphological and molecular variations. Morphological species boundaries were determined based on numerical taxonomic analyses of morphological characteristics in the uredinial and telial stages by cluster analysis and one-way analysis of variance. Phylogenetic species boundaries were delineated based on the generalized mixed Yule-coalescent (GMYC) model analysis of the sequences of the internal transcribed spacer (ITS1 and ITS2) regions including the 5.8S and D1/D2 regions of the large nuclear subunit of the ribosomal RNA gene. Numerical taxonomic analyses of 14 morphological characteristics recognized in the uredinial-telial stages revealed 22 morphological species, whereas the GMYC results recovered 29 phylogenetic species. In total, 17 morphological species were in concordance with the phylogenetic species and 5 morphological species were in concordance with 12 phylogenetic species. Both the morphological and molecular data supported 14 morphological characteristics, including 5 newly recognized characteristics and 9 traditionally emphasized characteristics, as effective for the differentiation of Melampsora species on willows in China. Based on the concordance and discordance of the two species delimitation approaches, we concluded that integrative taxonomy by using both morphological and molecular variations was an effective approach for delimitating Melampsora species on willows in China.

First Report of Pitch Canker Disease Caused by Rhizosphaera kalkhoffii on Pinus sylvestris in China

In November 2010, pitch canker disease was first discovered on Pinus sylvestris var. mongolica Litv. from Daxinganling region in Inner Mongolia Province, China, resulting in severe dieback and bark cracking on the host, accompanied by resin flowing profusely from cankers on the infected branches, cones, and trunks (2). The early stage symptoms consisted of sunken cankers, reddish-brown needles on infected twigs followed by heavy resin soaking of the wood as the disease progressed. Pieces of pitch-soaked wood (3 × 3 mm²) cut from cankerous tissue on branches were surface-sterilized with 0.4% NaOCl for 2 min and then rinsed twice in sterile distilled water. The fragments were placed on potato dextrose agar and incubated at 28°C in the dark. After 7 to 8 days, this process consistently yielded cultures with whitish, dense, aerial mycelium that later darkened to gray. Microconidia were single, oblong to cylindrical, aseptate, and 4 to 10 × 2 to 4 μm. Macroconidia were hyaline, 1- to 2-septate, oblong to cylindrical, with tiny papillae at both ends, and 10 to 13 × 2 to 5 μm, fitting the description of Rhizosphaera kalkhoffii (1). To verify the identification based on morphological features, the internal transcribed spacer (ITS) region of the ribosomal RNA genes was amplified using primers ITS1 (TCCGTAGGTGAACCTGCGG) and ITS4 (TCCTCCGCTTATTGATATGC) according to the published protocol (3), and then sequenced and compared to the GenBank database through BLAST search. Comparison of the sequences revealed 98% homology to R. kalkhoffii (EU700375.1 and EU700376.1). Representative sequences of R. kalkhoffii (JQ353721 and JQ353722) were deposited in GenBank. The pathogenicity of two representative isolates of R. kalkhoffii was also confirmed by spraying 40 μl of conidial suspension (4.6 × 10⁶ conidia/ml) on the bark surface of 20 2-year-old healthy pine seedlings, wounded by scratching with a sterilized knife. Sterile distilled water sprays were used for the controls. Within 4 to 8 weeks after inoculation, 90% of inoculated P. sylvestris exhibited symptoms of pitch cankers around the inoculation site similar to those on the original infection. R. kalkhoffii was consistently reisolated from all inoculated plants but not from water-treated controls, fulfilling Koch's postulates. R. kalkhoffii have previously been documented as pathogens of needle blight of Picea pungens (1). To our knowledge, this is the first report of R. kalkhoffii as a pathogen on Pinus sylvestris in China, and furthermore, pitch canker disease is currently listed as a quarantine disease in China, increasing the significance of this report. References: (1) J. Kumi et al. Eur. J. Forest Pathol. 9:35, 1979. (2) J. K. Lee et al. Plant Pathol. 16:52, 2000. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.