Xylariaceous Genera Research Articles

Studies on the secondary metabolism of Rosellinia and Dematophora strains (Xylariaceae) from Iran

The xylariaceous genus Dematophora has recently been resurrected and segregated from Rosellinia based on a molecular phylogeny and morphological characters. This was an important taxonomic change because Dematophora in the current sense contains several important pathogens, while Rosellinia is limited to mainly saprotrophic species that have an endophytic stage in their life cycle and may even have beneficial effects on the host plants. During our ongoing work on the functional biodiversity of the Xylariales, we have encountered new strains of rosellinoid Xylariaceae from Iran and have studied their mycelial cultures for secondary metabolites in an attempt to establish further chemotaxonomic affinities. In the process, we isolated and identified 13 compounds, of which rosellisteroid (1), the cichorine derivative 2, and the alkaloid 3 are new. Out of these, nine were tested for their antimicrobial affinities with cytochalasin E (6) exhibiting weak activity against Schizosaccharomyces pombe. The cytotoxicity of three cytochalasin derivatives was examined and their effects on the F-actin cytoskeletal organization studied by fluorescence microscopy using fluorescent phalloidin. Cytochalasin E (6) and Δ6,12-cytochalasin E (7) showed strong and irreversible action on actin, while cytochalasin K (8) exhibited weaker, reversible effects.

Contributions of North American endophytes to the phylogeny, ecology, and taxonomy of Xylariaceae (Sordariomycetes, Ascomycota)

The Xylariaceae (Sordariomycetes) comprise one of the largest and most diverse families of Ascomycota, with at least 85 accepted genera and ca. 1343 accepted species. In addition to their frequent occurrence as saprotrophs, members of the family often are found as endophytes in living tissues of phylogenetically diverse plants and lichens. Many of these endophytes remain sterile in culture, precluding identification based on morphological characters. Previous studies indicate that endophytes are highly diverse and represent many xylariaceous genera; however, phylogenetic analyses at the family level generally have not included endophytes, such that their contributions to understanding phylogenetic relationships of Xylariaceae are not well known. Here we use a multi-locus, cumulative supermatrix approach to integrate 92 putative species of fungi isolated from plants and lichens into a phylogenetic framework for Xylariaceae. Our collection spans 1933 isolates from living and senescent tissues in five biomes across the continental United States, and here is analyzed in the context of previously published sequence data from described species and additional taxon sampling of type specimens from culture collections. We found that the majority of strains obtained in our surveys can be classified in the hypoxyloid and xylaroid subfamilies, although many also were found outside of these lineages (as currently circumscribed). Many endophytes were placed in lineages previously not known for endophytism. Most endophytes appear to represent novel species, but inferences are limited by potential gaps in public databases. By linking our data, publicly available sequence data, and records of ascomata, we identify many geographically widespread, host-generalist clades capable of symbiotic associations with diverse photosynthetic partners. Concomitant with such cosmopolitan host use and distributions, many xylariaceous endophytes appear to inhabit both living and non-living plant tissues, with potentially important roles as saprotrophs. Overall, our study reveals major gaps in the availability of multi-locus datasets and metadata for this iconic family, and provides new hypotheses regarding the ecology and evolution of endophytism and other trophic modes across the family Xylariaceae.

A multiple gene genealogy reveals phylogenetic placement of Rhopalostroma lekae

Rhopalostroma lekae was collected on bark of wood in Chiang Rai Province, Northern Thailand and isolates from the sexual state produced a nodulosporium-like asexual state in culture. A combined multigene sequence analysis was used to infer the phylogenetic position of R. lekae and its affinities with other xylariaceous genera. Rhopalostroma is confirmed to have particularly close affinities with the genera Phylacia and Thamnomyces. Secondary metabolite profiling of R. lekae showed the species to produce binaphthalene tetrol (BNT) as a major metabolite and several minor undetermined metabolites. The phylogenetic placement of R. lekae was resolved using a polythetic approach. Herbarium material and living cultures representing an authentic specimen of R. lekae are deposited in publically accessible collections that can be used in future studies.

Ascus apical apparatus and ascospore characters in Xylariaceae

Members of Xylariaceae (Ascomycota) are recognized and classified mainly on the morphological features of their sexual state. In a number of genera high morphological variation of stromatal characters has made confident recognition of generic and specific boundaries difficult. There are, however, a range of microscopical characteristics which can in most cases make distinctions, especially at generic level, even in the absence of molecular data. These include details of the apical apparatus in the ascus (e.g. disc-shaped, inverted hat-shaped, rhomboid, composed of rings, amyloid, non-amyloid); position and length of the germ slit; and presence and type of ascospore wall ornamentation as seen by scanning electron microscopy (SEM). Unfortunately many of the classical studies on xylariaceous genera omitted these features and were undertaken long before the development of scanning electron microscopy. More recent studies have, however, demonstrated their value as diagnostic characters in the family. Camillea is for example, instantly recognizable by its rhomboid or diamond shaped apical apparatus, and the distinctive inverted hat or urniform type is usually prominent in Xylaria, Rosellinia, Kretzschmaria, and Nemania. At least six categories of apical apparatus based on shape and size can be recognized. Ascospore ornamentation as seen by SEM has been exceptionally useful and provided the basis for separating Camillea from Biscogniauxia and other xylariaceous genera.

The Xylariaceae of the Hawaiian Islands.

Keys, species notes, references, hosts, and collection locations of the following xylariaceous genera are included: Annulohypoxylon, Ascovirgaria, Biscogniauxia, Daldinia, Hypoxylon, Jumillera, Kretzschmaria, Lopadostoma, Nemania, Rosellinia, Stilbohypoxylon, Xylaria, and Xylotumulus. Camarops and Pachytrype --non-xylariaceous genera--are included. Anthostomella, well-covered elsewhere, is not included here. A Host-Fungus Index is included. A new name, Xylaria alboareolata , is proposed. All of the Hawaiian Islands are included, but Lanai was not visited.

The phylogenetic position of <I>Rhopalostroma</I> as inferred from a polythetic approach

The xylariaceous genus Rhopalostroma comprises a small conglomerate of stromatic, angiosperm-associated pyrenomycetes, which have so far exclusively been reported from the palaeotropics, above all from tropical Africa and South Asia. Morphological and chemotaxonomic studies had suggested their close relationship to the genera Daldinia and Hypoxylon. However, those results were mainly based on herbarium specimens, and no molecular phylogenetic data were available on Rhopalostroma. During a foray in Côte d'Ivoire, fresh material of R. angolense was collected, cultured and studied by microscopic methods and by secondary metabolite profiling using high performance liquid chromatography coupled with diode array and mass spectrometric detection. In addition, ITS nrDNA sequences of the cultures were generated and compared to those of representative Xylariaceae taxa, to evaluate the phylogenetic affinities of this fungus. The results showed that R. angolense is closely related to the daldinoid Xylariaceae, and in particular to the predominantly neotropical genera Phylacia and Thamnomyces.

Molecular phylogeny of Hypoxylon and closely related genera

Phylogenetic relationships were inferred among several xylariaceous genera with Nodulisporium or nodulisporium-like anamorphs based on the analyses of β-tubulin and α-actin sequences. One hundred nine cultures and three specimens of 83 representatives of these four genera were included in the study. Biscogniauxia taxa formed a well supported clade that was basal to the other taxa, while taxa of Hypoxylon and Daldinia comprised a large monophyletic group that contained two subclades. The first subclade encompassed Hypoxylon sect. Annulata and is accepted here as the new genus Annulohypoxylon. The second subclade contained taxa of Hypoxylon sect. Hypoxylon and Daldinia. Hypoxylon is restricted to include only those taxa in sect. Hypoxylon. Thirty-three epithets are made in Annulohypoxylon. Hypoxylon cohaerens var. microsporum is raised to the species level and accepted as A. minutellum. Hypoxylon polyporoideum is recognized as distinct from H. crocopeplum. Hypoxylon placentiforme is accepted as Daldinia placentiformis.

Molecular phylogeny of Hypoxylon and closely related genera

Phylogenetic relationships were inferred among several xylariaceous genera with Nodulisporium or nodulisporium-like anamorphs based on the analyses of beta-tubulin and alpha-actin sequences. One hundred nine cultures and three specimens of 83 representatives of these four genera were included in the study. Biscogniauxia taxa formed a well supported clade that was basal to the other taxa, while taxa of Hypoxylon and Daldinia comprised a large monophyletic group that contained two subclades. The first subclade encompassed Hypoxylon sect. Annulata and is accepted here as the new genus Annulohypoxylon. The second subclade contained taxa of Hypoxylon sect. Hypoxylon and Daldinia. Hypoxylon is restricted to include only those taxa in sect. Hypoxylon. Thirty-three epithets are made in Annulohypoxylon. Hypoxylon cohaerens var. microsporum is raised to the species level and accepted as A. minutellum. Hypoxylon polyporoideum is recognized as distinct from H. crocopeplum. Hypoxylon placentiforme is accepted as Daldinia placentiformis.

Morphological studies in Rosellinia (Xylariaceae): the first step towards a polyphasic taxonomy

More than 90 species are accepted in the xylariaceous genus Rosellinia. Thorough morphological characterisation of all known species will provide a taxonomic hypothesis that can be later tested by DNA sequence analysis. Exploratory analyses of ascospore morphology, shape of ascus apical structure, and anamorph genus suggest six morphological groups in the genus.

Poroleprieuria, a New Xylariaceous Genus from Mexico

Poroleprieuria gen. nov. is described and illustrated to accommodate P. rogersii in the Xylariaceae, Xylariales. This ascomycete, known only from the type collection, is characterized by reniform, light brown, smooth ascospores with a germ pore; cylindrical, persistent asci lacking an apical apparatus, septate persistent paraphyses, and erumpent, erect, dark brown, fragile, subcylindrical stromata. The characteristics of this xylariaceous fungus were compared with those of some other ascomycetes having superficially similar cylindrical stromata or ascospores with germ pores.

Poroleprieuria, a new xylariaceous genus from Mexico

Poroleprieuria gen. nov. is described and illustrated to accommodate P. rogersii in the Xylariaceae, Xylariales. This ascomycete, known only from the type collection, is characterized by reniform, light brown, smooth ascospores with a germ pore; cylindrical, persistent asci lacking an apical apparatus, septate persistent paraphyses, and erumpent, erect, dark brown, fragile, subcylindrical stromata. The characteristics of this xylariaceous fungus were compared with those of some other ascomycetes having superficially similar cylindrical stromata or ascospores with germ pores.

Entonaema in Thailand

The presence of the xylariaceous genus Entonaema in Thailand is confirmed. One collection from Chiang Mai Province, E. siamensis, is described as new.

Camillea, Jongiella and light-spored species of Hypoxylon

The relationship of Camillea with other xylariaceous genera, particularly with those applanate species of Hypoxylon which have light-coloured ascospores ornamented with reticulations or ribs is discussed. Camillea broomeiana and C. signata, taxa with spiny ascospores, are proposed as new combinations and placed in Camillea subgen. Jongiella. The following new combinations are made for species usually placed in Hypoxylon: Camillea cycliscus, C. flosculosa, C. fossulata, C. gigaspora, C. hainesii, C. heterostoma, C. heterostoma var. macrospora, C. punctidisca, C. punctulata, C. scriblita, C. sulcata, C. tinctor. The genus Leprieuria is erected to accommodate C. bacillum. Additionally, C. patouillardii C. oligoporus, C. stellata, C. amazonica and C. deceptiva from Peru and Ecuador are described as new and a key to the species of the now considerably enlarged genus is provided. References and descriptions are made to anamorphs of several species, all of which are assigned to Xylocladium. Camillea leprieurii is shown to possess a dimorphic teleomorph with the applanate form previously known as H. melanaspis.

Helicogermslita, a new stromatic Xylariaceous genus with a spiral germ slit from India

Helicogermslita gen.nov. is introduced for the single species, H. celastri (S. Kale & V. Kale) comb.nov. (syn. Amphisphaerella celastri S. Kale & V. Kale, Anthostomella spirilla Panwar & Kaur). The ascomata usually arise singly but have a multilayered wall indicating that they are stromatic; this is confirmed by the outer layers occasionally embracing more than a single perithecial cavity. The ascospores have a deep germ slit running helically around them. The asci are non-amyloid, but the germ slit and the stromatic ascomata indicate that the genus is most appropriately interpreted as a highly specialized genus of the Xylariaceae.