Biomedical subjects

Lisa A Castlebury

Publications and source records attributed to Lisa A Castlebury.

6 recordsLinked to original sources

PubMed2006

Connection of Gnomonia intermedia to Discula betulina and its relationship to other taxa in Gnomoniaceae.

Discula betulina is a foliar pathogen on birch (Betula) and Gnomonia intermedia is found on overwintered birch leaves. Perithecia of G. intermedia developed in vitro on colonies of D. betulina isolated from birch tissues in late summer, and single ascospores of G. intermedia consistently developed into colonies similar to D. betulina, producing typical D. betulina conidia. Isolates of D. betulina could be grouped into two mating types, which produced fertile perithecia of G. intermedia when mated with each other. Mycelia from single-ascospore and single-conidial isolates were inoculated onto shoots of downy birch, causing lesions and die-back from which D. betulina was consistently isolated. ITS region ribosomal DNA sequence analysis confirmed the results of the morphological and mating studies, and found that the closest known relatives of G. intermedia/D. betulina are Gnomoniella nana and Sirococcus clavigignenti-juglandacearum. The conclusion from these studies is that D. betulina is the anamorph of G. intermedia.

Ascomycota↗

PubMed2006

Nonsystemic bunt fungi--Tilletia indica and T. horrida: a review of history, systematics, and biology.

The genus Tilletia is a group of smut fungi that infects grasses either systemically or locally. Basic differences exist between the systemically infecting species, such as the common and dwarf bunt fungi, and locally infecting species. Tilletia indica, which causes Karnal bunt of wheat, and Tilletia horrida, which causes rice kernel smut, are two examples of locally infecting species on economically important crops. However, even species on noncultivated hosts can become important when occurring as contaminants in export grain and seed shipments. In this review, we focus on T. indica and the morphologically similar but distantly related T. horrida, considering history, systematics, and biology. In addition, the controversial generic placement and evolutionary relationships of these two species are discussed in light of recent molecular studies.

Fungi↗

PubMed2004

Multigene phylogeny reveals new lineage for Stachybotrys chartarum, the indoor air fungus.

Stachybotrys chartarum is an asexually reproducing fungus commonly isolated from soil and litter that is also known to occur in indoor environments and is implicated as the cause of serious illness and even death in humans. Despite its economic importance, higher level phylogenetic relationships of Stachybotrys have not been determined nor has a sexual state for S. chartarum been reported. DNA sequences from four nuclear and one mitochondrial gene were analyzed to determine the ordinal and familial placement of Stachybotrys within the Euascomycota. These data reveal that species of Stachybotrys including S. chartarum, S. albipes, for which the sexual state Melanopsamma pomiformis is reported, species of Myrothecium, and two other tropical hypocrealean species form a previously unknown monophyletic lineage within the Hypocreales. These results suggest that Stachybotrys and Myrothecium are closely related and share characteristics with other hypocrealean fungi. In addition, S. chartarum may have a sexual state in nature that consists of small, black, fleshy perithecia similar to Melanopsamma.

Air Microbiology↗

PubMed2003

Multilocus phylogenetic structure within the Trichoderma harzianum/Hypocrea lixii complex.

Trichoderma harzianum is a ubiquitous species in the environment and is effective in the biological control of plant-pathogenic fungi. T. harzianum has not been linked unequivocally to its sexual state nor has its phylogeny been studied in detail. It has been suggested that T. harzianum is a species complex based on the phenotypic and genotypic variability encountered. On the basis of morphological and cultural characters and DNA sequence data analysis of four genes (ITS rDNA, translation elongation factor 1-alpha, calmodulin, and alpha-actin), Hypocrea lixii was found to be the sexual state of T. harzianum. Both the asexual and sexual states of this species have wide geographic distributions. Phylogenetic analysis of four genes showed that T. harzianum/H. lixii is a cohesive group that is supported by bootstrap values higher than 95%. Principles of genealogical concordance indicated that T. harzianum/H. lixii is a complex of independent monophyletic lineages, but no diagnostic morphological distinctions were identified that justify formal taxonomic recognition for the different lineages.

Actins↗

PubMed2003

Neophaeosphaeria and Phaeosphaeriopsis, segregates of Paraphaeosphaeria.

Two new genera, Neophaeosphaeria and Phaeosphaeriopsis, are described to accommodate species of Paraphaeosphaeria that are not congeneric based on morphological characters and results of 18S rDNA sequence analyses. Paraphaeosphaeria s. str. is restricted to species with two-septate ascospores and anamorphs that produce non-septate, smooth, pale brown conidia enteroblastically from phialides which have some periclinal thickening. Species in Neophaeosphaeria have 3-4-septate ascospores and anamorphs that produce ovoid to ellipsoid, non-septate, brown, verrucose or punctate conidia from percurrently proliferating conidiogenous cells. Paraphaeosphaeria barrii, P. conglomerata, P. filamentosa and P. quadriseptata are transferred to Neophaeosphaeria. At present all species in Neophaeosphaeria occur on Yucca (Agavaceae). Phaeosphaeriopsis is described for species that produce 4-5-septate ascospores. Known anamorphs produce cylindrical, 0-3-septate, brown, punctate conidia from percurrently proliferating conidiogenous cells or bacillar conidia from simple phialides. P. agavensis, P. glauco-punctata, P. nolinae and P. obtusispora are transferred to Phaeosphaeriopsis. P. amblyspora is described as a new species.

Ascomycota↗

PubMedDate not supplied

Phylogenetic analysis of Tilletia and allied genera in order Tilletiales (Ustilaginomycetes; Exobasidiomycetidae) based on large subunit nuclear rDNA sequences.

The order Tilletiales (Ustilaginomycetes, Basidiomycota) includes six genera (Conidiosporomyces, Erratomyces, Ingoldiomyces, Neovossia, Oberwinkleria and Tilletia) and approximately 150 species. All members of Tilletiales infect hosts in the grass family Poaceae with the exception of Erratomyces spp., which occur on hosts in the Fabaceae. Morphological features including teliospore ornamentation, number and nuclear condition of primary basidiospores and ability of primary basidiospores to conjugate and form an infective dikaryon were studied in conjunction with sequence analysis of the large subunit nuclear rDNA gene (nLSU). Analysis based on nLSU data shows that taxa infecting hosts in the grass subfamily Pooideae form one well supported lineage. This lineage comprises most of the reticulate-spored species that germinate to form a small number of rapidly conjugating basidiospores and includes the type species Tilletia tritici. Two tuberculate-spored species with a large number of nonconjugating basidiospores, T. indica and T. walkeri, and Ingoldiomyces hyalosporus are also included in this lineage. Most of the species included in the analysis with echinulate, verrucose or tuberculate teliospores that germinate to form a large number (>30) of nonconjugating basidiospores infect hosts in the subfamilies Panicoideae, Chloridoideae, Arundinoideae and Ehrhartoideae. This group of species is more diverse than the pooid-infecting taxa and in general do not form well supported clades corresponding to host subfamily. The results of this work suggest that morphological characters used to segregate Neovossia, Conidiosporomyces and Ingoldiomyces from Tilletia are not useful generic level characters and that all included species can be accommodated in the genus Tilletia.

Basidiomycota↗