Genus Hypoxylon Research Articles

Chemotaxonomic and molecular phylogenetic studies of selected Hypoxylon species from the Neotropics

ABSTRACT Members of the genus Hypoxylon (Ascomycota) are pleomorphic fungi mostly forming conspicuous teleomorphs, consisting of perithecia embedded into stromal tissue, and their morphology has traditionally served for species delineation. However, analysis in tandem with other phenotypic characters, such as chemical and genetic traits, proved to be a more stable predictor of interspecies and intergeneric relationships. During 2014 and 2015, a set of species identified as Hypoxylon were described from the Neotropics, exclusively relying on morphological traits. The secondary metabolite profiles of their stromata were analysed by HPLC/DAD-ESI-MS, corroborating their classification within Xylariales. Additionally, molecular data for ex-type strains of H. dussii and H. sofaiense were incorporated into an inferred molecular phylogeny of the Hypoxylaceae and allies. Furthermore, a freshly collected specimen from North Carolina was selected as epitype of Sphaeria perforata Schweinitz (syn. Hypoxylon perforatum), as its morphological/chemotaxonomic characters matched those of the holotype. Our findings demonstrate that the secondary metabolism of Hypoxylon closely correlates with both morphological features and molecular data, serving as a complement for species identification.

Multi-Locus Phylogeny and Morphology Reveal Two New Species of Hypoxylon (Hypoxylaceae, Xylariales) from Motuo, China.

Hypoxylaceous fungi are abundant in China, but their discovery and report are uneven in various provinces, with more fungi in Yunnan and Hainan and fewer fungi in Tibet. During the investigation of macro-fungi in Motuo county, Tibet Autonomous Region, we collected a number of xylarialean specimens. Six hypoxylaceous specimens growing on dead angiosperm were collected from the forests of Motuo county, and they were described and illustrated as two new species in Hypoxylon based on a combination of morphological characters and molecular evidence. Hypoxylon diperithecium was characterized by its bistratal perithecia, purple-brown stromatal granules, citrine to rust KOH-extractable pigments, and light brown to brown ascospores ellipsoid-inequilateral with conspicuous coil-like ornamentation. Hypoxylon tibeticum was distinct from other species by having pulvinate and applanate stromata, surface vinaceous, with orange granules, orange KOH-extractable pigments, and brown ascospores with inconspicuous ornamentation. The multi-gene phylogenetic analyses (ITS-LSU-RPB2-TUB) supported the two new taxa as separate lineages in the genus Hypoxylon. A key to all known Hypoxylon taxa from China is provided.

Multi-Gene Phylogeny and Taxonomy of Hypoxylon (Hypoxylaceae, Ascomycota) from China

The Hypoxylon species play an important ecological role in tropical rainforest as wood-decomposers, and some might have benefical effects on their hosts as endophytes. The present work concerns a survey of the genus Hypoxylon from Hainan Tropical Rainforest National Park of China. Four new species: H. wuzhishanense, H. hainanense, H.chrysalidosporum, and H.cyclobalanopsidis, were discovered based on a combination of morphological characteristics and molecular data. Hypoxylon wuzhishanense is characterized by Rust pulvinate stromata, amyloid apical apparatus and brown ascospores, with most of the perispore being indehiscent in 10% KOH. Hypoxylon hainanense has effused–pulvinate and Violet stromata, amyloid apical apparatus, light-brown to brown ascospores with straight germ slit and dehiscent perispore. Hypoxylonchrysalidosporum is distinguished by glomerate to pulvinate stromata, highly reduced or absent inamyloid apical apparatus, and light-brown to brown ascospores with very conspicuous coil-like ornamentation. Hypoxyloncyclobalanopsidis has Livid Purple pulvinate stromata, highly reduced amyloid apical apparatus, faint bluing, brown ascospores and dehiscent perispore, and it grows on dead branches of Cyclobalanopsis. Detailed descriptions, illustrations, and contrasts with morphologically similar species are provided. Phylogenetic analyses inferred from ITS, RPB2, LSU, and β-tubulin sequences confirmed that the four new species are distinct within the genus Hypoxylon.

Isolation and functional characteristics of the fungus Hypoxylon spp. Sj18 with biocontrol potential

A fungus with biocontrol potential was isolated from the roots of hickory trees. The strain named sj18 was classified as a member of the genus Hypoxylon (Hypoxylaceae) after multigene phylogenetic analysis (beta-tubulin gene, internal transcribed spacer, 28S large subunit ribosomal RNA gene, and RNA polymerase II subunit gene). The strain grew well on a PDA with an optimum temperature range between 32 and 34 °C. The fungus had obvious inhibitory effects on Botryosphaeria dothidea, Colletotrichum gloeosporioides, and Gibberella moniliformis in fumigation experiments on solid agar plates. In an inoculation experiment of Chinese cabbage, the fungus was also found to have an obvious repellent effect on cabbage caterpillars. In vitro experiments on Petri dishes showed that the fermentation broth of the sj18 strain could kill 100% of Bursaphelenchus xylophilus within 8 h even if the fermentation broth was diluted 8 times. The inoculation test of Arabidopsis thaliana showed that the fungus could promote the lateral root formation of plants and significantly increase their aboveground biomass. Through the analysis of solid phase microextraction (SPME), it was found that the main volatile components of the fermentation products were azulene 65.39% (61.77% + 3.62%), caryophyllene 7.41%, and eucalyptol 6.83% according to the peak area ratio. Therefore, sj18 can be used as a candidate for the further research and development of biocontrol agents.

El género Hypoxylon (Xylariales, Ascomycota) en el bosque tropical caducifolio de cuatro Áreas Naturales Protegidas de México.

Antecedentes y Objetivos: El género Hypoxylon (Hypoxylaceae) tiene peritecios embebidos en un estroma oscuro o de colores brillantes, efuso-aplanado, efuso-pulvinado o glomerulado, ascas cilíndricas con poro apical amiloide, ascosporas elipsoides, equiláteras o inequiláteras, marrón claro a marrón oscuro, línea germinal recta o sigmoide y perisporio generalmente dehiscente con KOH al 10%. El género tiene una distribución mundial; se han descrito 115 especies con mayor diversidad en las regiones tropicales. En México se tenían registrados 36 taxones, de los cuales 20 se citan del bosque tropical caducifolio. El objetivo del presente estudio es ampliar la distribución conocida y describir las especies de Hypoxylon que crecen en el bosque tropical caducifolio de cuatro Áreas Naturales Protegidas (ANPs) de México.Métodos: Se realizaron seis exploraciones en las siguientes ANPs de México: Reserva de la Biosfera Chamela-Cuixmala (Jalisco), Reserva de la Biosfera Isla Cozumel (Quintana Roo), Reserva de la Biosfera Sierra de Álamos-Río Cuchujaqui (Sonora) y Reserva de la Biosfera El Cielo (Tamaulipas). Los ejemplares recolectados fueron estudiados, descritos y determinados de acuerdo con las técnicas tradicionales en micología. El material está depositado en el herbario ENCB.Resultados clave: Se determinaron 11 especies de Hypoxylon, y se describe por primera vez para México Hypoxylon jaklitschii de Jalisco, Quintana Roo y Tamaulipas. Además, se amplía la distribución conocida de H. anthochroum, H. cinnabarinum, H. erythrostroma, H. haematostroma, H. investiens, H. lividipigmentum, H. perforatum, H. rickii e Hypoxylon subgilvum a otros estados.Conclusiones: Hypoxylon está bien representado en México, siendo uno de los mejor estudiados del orden Xylariales. Hypoxylon cinnabarinum, H. haematostroma e H. lenormandii se encontraron en todas las ANPs del presente estudio. La Reserva de la Biosfera el Cielo es el ANP con mayor número de especies con nueve.

Pest categorisation of Entoleucamammata.

Following a request from the European Commission, the EFSA Plant Health (PLH) Panel performed a pest categorisation of Entoleuca mammata, a well‐defined and distinguishable fungus of the family Xylariaceae native to North America. The species was moved from the genus Hypoxylon to the genus Entoleuca following a revision of the genus. The former species name H. mammatum is used in the Council Directive 2000/29/EC. E. mammata is the causal agent of Hypoxylon canker of quaking aspen (Populus tremuloides) and other poplars (Populus spp.). The pathogen has been reported in 16 EU Member States (MS), without apparent limiting ecoclimatic factors, but mostly (with the exception of Sweden) with a restricted distribution. E. mammata is a protected zone (PZ) quarantine pest (Annex IIB) for Ireland and the UK (Northern Ireland). The main hosts present in the EU (P. tremula, P. nigra and hybrid poplars) are widespread throughout most of the risk assessment area, including the PZ. The main means of spread are wind‐blown ascospores, plants for planting and wood with bark. E. mammata is not currently reported to be of significant economic importance in the EU MS where the pathogen is reported, but has been shown to cause significant damage in the USA. Risk reduction options include appropriate site selection for poplar plantations, avoiding wounds, and debarking wood. The main uncertainties concern the distribution of the pathogen in the EU, the susceptibility of cultivated hybrid poplars to the pathogen and thus the potential damage to poplar plantations in the RA area. The criteria assessed by the Panel for consideration as potential PZ quarantine pest are met. The criterion of plants for planting being the main pathway for spread for regulated non‐quarantine pests is not met: plants for planting are only one of the means of spread of the pathogen.

Terphenyl derivatives and drimane – Phathalide/isoindolinones from Hypoxylon fendleri BCC32408

The genus Hypoxylon, a member of the family Xylariaceae, has been known to produce significant secondary metabolites in terms of chemical diversity. Moreover, the compounds isolated can also be used as chemotaxonomic characters for differentiation among the two sections, which are sect. Annulata and sect. Hypoxylon. In our continuing chemical screening programme for novel compounds, the crude extracts of H. fendleri BCC32408 gave significant chemical profiles in HPLC analyses. Thus, the chemical investigation of these crude extracts was then carried out. The investigation led to the isolation of ten previously undescribed compounds including three terphenylquinones (fendleryls A – C), one terphenyl (fendleryl D), and six novel drimane – phthalide-type lactone/isoindolinones derivatives (fendlerinines A – F) along with seven known compounds (2-O-methylatromentin, rickenyl E, atromentin, rickenyls C – D, (+)-ramulosin, and O-hydroxyphenyl acetic acid). The chemical structures were determined on the basis of spectroscopic analyses, including 1D, 2D NMR and high-resolution mass spectrometry, as well as chemical transformations. In addition, these isolated compounds were assessed for antimicrobial activity including antimalarial (against Plasmodium falciparum, K-1 strain), antifungal (against Candida albicans), antibacterial (against Bacillus cereus) activities. Cytotoxicity against both cancerous (KB, MCF-7, NCI-H187) and non-cancerous (Vero) cells of these compounds were also evaluated.

Phylogenetic and chemotaxonomic resolution of the genus Annulohypoxylon (Xylariaceae) including four new species

This study deals with an extensive evaluation focusing on phylogenetic and chemotaxonomic infrageneric relationships of the genus Annulohypoxylon (Xylariaceae, Ascomycota), whose species are ubiquitously associated with seed plants as endophytes and saprotrophs in all forested areas of the world. Using evidence from phylogenetic, chemotaxonomic and morphological data, various varieties within the genus are raised to species level, leading to the new combinations for A. areolatum (≡ A. bovei var. microsporum), A. macrosporum (≡ A. leptascum var. macrosporum), and A. microdiscum (≡ A. moriforme var. microdiscum). Annulohypoxylon substygium nom. nov. is applied for A. stygium var. annulatum and the four new tropical and subtropical species A. massivum, A. violaceopigmentum, A. viridistratum and A. yungensis are introduced. Furthermore, A. leucadendri is excluded from the genus as its morphological characters disagree with the generic concept, the recently erected A. palmicola is synonymized with A. leptascum and A. austrobahiense has been reassigned to the genus Hypoxylon. In addition, the key taxa A. annulatum and A. truncatum have been reinvestigated and epitypes have been defined. For the first time, a dichotomous key to the genus is provided. A phylogenetic β-tubulin tree in conjunction with stromatal HPLC profiles clearly shows that Annulohypoxylon comprises two distinct lineages. The A. cohaerens/multiforme group might eventually warrant segregation into a new genus as further molecular data become available.

Chemical Constituents of the Endophytic Fungus Hypoxylon sp. 12F0687 Isolated from Taiwanese Ilex formosana

AbstractBioassay‐guided fractionation of an AcOEt‐soluble fraction of the liquid fermentation of an endophytic fungus Hypoxylon sp. BCRC 12F0687 associated with the root of Taiwanese Ilex formosana (Aquifoliaceae) resulted in the isolation of two new compounds, i.e., one benzenoid, hypoxyphenone (1), and one azaphilone derivative, hypoillexidiol (2), two metabolites isolated for the first time from natural source, (−)‐(3S)‐3‐hydroxy‐3‐methyloxindole (3) and (+)‐vermelone (4), along with twelve previously identified compounds, 5–16. Their structures were determined through in‐depth spectroscopic and mass‐spectrometric analyses. The effects of some isolates on the inhibition of NO and IL‐6 production in lipopolysaccharide‐activated RAW 264.7 murine macrophages were evaluated. Of the isolates, 2 and 3 exhibited potent anti‐NO production activity, with IC50 values of 17.5±1.8 and 24.7±1.6 μM, respectively, compared to that of quercetin, an iNOS inhibitor with an IC50 value of 35.9±1.7 μM. Compounds 2, 4, 5, and 12 also showed moderate inhibition of IL‐6 production, with IC50 values ranging from 27.2±1.8 to 35.3±5.8 μM. This is the first report on an oxindole metabolite from the genus Hypoxylon.

Inhibitory effects of constituents of an endophytic fungus Hypoxylon investiens on nitric oxide and interleukin-6 production in RAW264.7 macrophages.

Three new compounds, hypoxyloamide (1), 8-methoxynaphthalene-1,7-diol (2), and hypoxylonol (3), together with seven compounds isolated from nature for the first time, investiamide (4), hypoxypropanamide (5), hypoxylonol A (6), investienol (7), 2-heptylfuran (8), (3S)-5-methyl-8-O-methylmellein (9), (4R)-O-methylsclerone (10), along with 19 known compounds, 11-29, were isolated from the culture broth of Hypoxylon investiens BCRC 10F0115, a fungal endophyte residing in the stems of an endemic Formosan plant Litsea akoensis var. chitouchiaoensis. The structures of the new compounds were established by spectroscopic methods, including UV, IR, HR-ESI-MS, and extensive 1D- and 2D-NMR techniques. Of these isolates, 2, 8-methoxynaphthalen-1-ol (15), and 1,8-dimethoxynaphthalene (16) showed nitric oxide (NO) inhibitory activity with IC50 values of 11.8±0.9, 17.8±1.1, and 13.3±0.5 μM, respectively, stronger than the positive control quercetin (IC50 36.8±1.3 μM). Compounds 2, 15, and 16 also showed interleukin-6 (IL-6) inhibitory activity with IC50 values of 9.2±1.7, 18.0±0.6, and 2.0±0.1 μM, stronger than the positive control quercetin (IC50 31.3±1.6 μM). To the best of our knowledge, this is the first report on guaiane sesquiterpene metabolites, 3, 6, and 7, from the genus Hypoxylon.

Biodiversity of foliar fungal endophytes in white spruce (Picea glauca) from southern Québec

The objective of this study was to investigate the foliar endophyte biodiversity of white spruce ( Picea glauca (Moench) Voss to establish a baseline for future comparative studies examining the impact of forestry practices. It identifies for the first time endophytic fungi living inside the needles of white spruce from 280 needles collected in seven natural stands in southern Québec. The endophyte colonization rate on surface sterilized needles was 53.2%. We performed a PCR-RFLP and sequence analysis on the ITS region of the nuclear ribosomal DNA to achieve molecular identification. Isolate ITS sequences were compared with data from GenBank presenting the best similarity and were analyzed by a maximum of parsimony and Bayesian inference. Relationships between morphological groups, digestion groups, and sequence groups were investigated. In all, 23 morphotypes were found to belong to 14 sequence groups and we demonstrated that morphological groups are poor indicators for estimating species diversity. This study is the first to establish species richness values for foliar endophytes. Among the 141 isolates in this study, 75.15% have a high sequence similarity with Lophodermium piceae , 10.95% with an unknown species of Mycosphaerella , and 5.5% with two species of the genus Hypoxylon . Distribution, incidence and biological significance of all the endophytes found in this study are discussed.

Hypoxylon species on beech and other broadleaves

Fungi in the genus Hypoxylon cause wood decay and most of them are saprophytes on dead wood or parasites of weakness. The following species in this genus were identified in this study performed at several localities in Serbia and Montenegro: H. deustum, H. fragiforme, H. nummularium, H. multiforme, H. rubiginosum and H. fuscum. Among them the most significant species is H. deustum, the fungus causing root and butt rot of standing beech trees. It was recorded from all coppice and high forests of beech. This paper presents the morphological characteristics of the recorded fungi their range, plant hosts and significance.

First Report of Hypoxylon diatrypeoides Inducing Dieback and Black Trunk Rot on Mesquite (Prosopis laevigata) in Mexico.

During 2001, branch dieback, black trunk rot, and resinosis were observed on mesquite in the biosphere reserve of Tehuacan, Mexico (18°15'N, 97°25'W) A light brown growth, which included Nodulosporium-like conidiosphores and hyaline conidia that were green in mass and ellipsoid with one end truncate developed on diseased branches. Below the conidiophores and conidia, glomerate to pulvinate stromata formed with conspicuous, black, perithecial mounds with globose perithecia. Ascospores were dark brown, unicellular, ellipsoid, nonequilateral, with narrowly rounded ends, a straight germ slit with a perispore that was dehiscent in 10% KOH, and a conspicuous coil-like, smooth epispore. Sexual reproduction was induced on sterile toothpicks in potato dextrose agar, malt extract agar, or V8 agar (with 10% calcium chloride). The fungus was identified as Hypoxylon diatrypeoides Rehm (1). Samples of mesquite branches with stromata of H. diatrypeoides were deposited in the J. H. Miller Herbarium of the University of Georgia (GAM16048). During the summer of 2002, three pathogenicity tests were performed under greenhouse conditions using three healthy young mesquite plants (25 cm high) per treatment per test. The treatments were: (i) inoculation of branches by wounding with a colonized toothpick from V8 agar, covered with mycelium and perithecia; (ii) spraying ascospores on branches previously wounded with a sterile toothpick; (iii) spraying ascospores on unwounded plants; (iv) plants wounded with sterile toothpicks; and (v) unwounded and uninoculated plants. Fifteen days after inoculation, branch dieback and black trunk rot symptoms were induced in 100% of mesquite plants inoculated with toothpicks and in 50% of wounded plants inoculated with ascospores. No symptoms were seen in the unwounded plants and control treatments. H. diatrypeoides was reisolated from the symptomatic branches. Previously, the fungus had been reported only from the Southern Hemisphere (Brazil and New Zealand), but to our knowledge, this is the first report from Mexico and the Northern Hemisphere. This is also the first evidence of its role as a plant pathogen. Reference: (1) Y. M. Ju and J. D. Rogers. A revision of the genus Hypoxylon. Mycologia Memoir No 20. The American Phytopathological Society, St. Paul, MN, 1996.

Macrocarpones, novel metabolites from stromata of Hypoxylon macrocarpum, and new evidence on the chemotaxonomy of Hypoxylon species

Several species of the genus Hypoxylon (Xylariaceae) were studied for morphological characters and HPLC-based secondary metabolite profiles. It was confirmed that Hypoxylon is divided into two groups of species, containing either Mitorubrin type azaphilones or binaphthyls, respectively, as main metabolites. In Hypoxylon species of the latter group, some metabolites that are known from the allied genus Daldinia (i.e., Daldinal A in H. fuscum and Daldinin C in H. fuscopurpureum), were encountered for the first time. Moreover, three novel aromatic polyketides, for which the trivial names Macrocarpones A, B and C are proposed, were isolated from ascostromata of Hypoxylon macrocarpum and identified by high resolution mass spectrometry and 2D-NMR spectroscopy. Orsellinic Acid was also identified from ascostromata of H. howeianum and detected by HPLC-MS and HPLC-UV/Vis fingerprinting methodology in H. fragiforme and H. rubiginosum, but not in other examined Hypoxylon species. Due to these studies, H. fuscopurpureum sensu Y.-M. Ju & J.D. Rogers 1996 was identified as a new record for Germany.

The genus Hypoxylon, Wood Decay Fungi – I. Teleomorph of Hypoxylon Section.

The genus Hypoxylon is a member of the Xylariaceae which has brown to dark brown and phaseoliform single cell ascospores with a conspicuous full germ slit. The isolates of Hypoxylon collected from England, Hong Kong and Korea are compared with similar taxa and described. These isolations under Hypoxylon section are detailed and illustrated, using light microscopy and scanning electron microscopy. Hypoxylon howeianum and H. rubiginosum are described and compared with former collection from Korea. A key to the species is also included.

The genus Hypoxylon, Wood Decay Fungi – II. Teleomorph of Annulata Section.

The section of Annulata under genus Hypoxylon is a member of the Xylariaceae which has ascomata with ostioles papillate in a flattened disc. The isolates of Hypoxylon collected from the TVopic to the Temperate are compared with similar taxa and described These isolations under Annulata section are illustrated with a light microscopy and a scanning electron microscopy. Hypoxylon archeri is newly recorded from Korea. A key to the species is also included.

Algunas especies de Hypoxylon (Pyrenomycetes, Xylariaceae) de México

Se presenta una clave artificial para 41 especies y tres variedades del género Hypoxylon sensu stricto, recolectadas en México al presente; 31 especies y una variedad pertenecen a la sección Hypoxylon, mientras que 10 especies y dos variedades corresponden a la sección Annulata. Dos taxa permanecen sin epíteto específico debido a la escasez del material o a la carencia de datos sobre sus anamorfos. Se propone como nueva a Hypoxylon shearii var. minor. Para cada taxon se proporcionan datos sobre distribución, substratos, fechas de recolecta y, en algunas, notas sobre afinidades con otras especies del género.

A Revision of the Genus Hypoxylon. Mycologia Memoir No. 20

A Revision of the Genus Hypoxylon. Mycologia Memoir No. 20

Xylariaceae of India-VII. The GenusRoselliniain the Northwest Himalayas

SUMMARY This paper records 10 taxa of the genus Rosellinia from India, viz.: R. aquila, R. thelena, R. himalayensis, R. apiculata var. macrospora, R. corticium, R. sublimbata, R. indica, R. thindii, R. mammiformis and R. medullaris. In addition to the morphology of the stromata, anatomy is also described for each species. A key to the taxa included is given. Of these R. himalayensis, R. indica and R. thindii are described as new species, R. apiculata var. macrospora as a new variety. The remaining six species are new records for India. De Notaris (1844) described the genus Rosellinia (Xylariaceae, Sphaeriales), based on Sphaeria aquila Fr. Subsequently several pyrenomycetes with globose ascocarps, with or without well-developed stroma, were included in the genus. Saccardo (1882) divided the genus into 10 subgenera based mainly upon the features of perithecia and subiculum. Miller (1928) for the first time showed the presence of a definite stroma around the perithecium in species of Rosellinia and considered them close to species of Hypoxylon. Martin (1967) suggested also that there were close affinities of species of Rosellinia with Miller's section Primocinerea of Hypoxylon. Martin proposed a new section, Entoleuca in the genus Hypoxylon, embracing species of Rosellinia, species of section Primocinerea of Hypoxylon, and a few other species of different groups. We have treated Rosellinia and Hypoxylon as separate genera following Dennis (1968) and Mfiller and Arx (1973). Rosellinia was previously represented in by 13 species. None was reported from the northwestern Himalayas except for two incompletely known species, R. andurensis Ces. & de Not. and R. bonaerensis Speg. These two species are listed in the Fungi of India by Butler and Bisby (1931), and are stated to be reported from Dehradun and Nainital respectively. The original material of both these collec

The genus Hypoxylon in Uganda forests

The genus Hypoxylon in Uganda forests