Research

    Donald H. Pfister

pic_pfister_umbrella.jpg

Curriculum Vitae (CV) 
 

Our lab group does research in the area of fungal biology in which we study taxonomy, life histories, and systematics – particularly of fungi in the Pezizomycetes, the Orbiliomycetes and recently in the Laboulbeniomycetes.  We are interested in the relationships among the members of these groups, their geographic distribution, and the associations of these fungi with other organisms.  Prof. Pfister has conducted research on topics related to documentation of collections and collectors of natural history specimens; particularly in relationship to the rich and varied collections at Harvard.  Our fieldwork ranges from collecting locally to southern South America.

Recent Publications

Secondary DNA Barcodes (CAM, GAPDH, GS, and RpB2) to Characterize Species Complexes and Strengthen the Powdery Mildew Phylogeny

Bradshaw, M., et al., 2022. Secondary DNA Barcodes (CAM, GAPDH, GS, and RpB2) to Characterize Species Complexes and Strengthen the Powdery Mildew Phylogeny. Frontiers in Ecology and Evolution. Publisher's VersionAbstract
Powdery mildews are a group of economically and ecologically important plant pathogens. In the past 25 years the use of ribosomal DNA (rDNA) in the powdery mildews has led to major taxonomic revisions. However, the broad scale use of rDNA has also revealed multiple species complexes that cannot be differentiated based on ITS + LSU data alone. Currently, there are only two powdery mildew taxonomic studies that took a multi-locus approach to resolve a species complex. In the present study, we introduce primers to sequence four additional regions (CAM, GAPDH, GS, and RPB2) that have the potential to improve support values in both broad and fine scale phylogenetic analyses. The primers were applied to a broad set of powdery mildew genera in China and the United States, and phylogenetic analyses included some of the common complexes. In taxa with nearly identical ITS sequences the analyses revealed a great amount of diversity. In total 154 non-rDNA sequences from 11 different powdery mildew genera were deposited in NCBI’s GenBank, laying the foundation for secondary barcode databases for powdery mildews. The combined and single loci phylogenetic trees constructed generally followed the previously defined species/genus concepts for the powdery mildews. Future research can use these primers to conduct in depth phylogenetic, and taxonomic studies to elucidate the evolutionary relationships of species and genera within the powdery mildews.
Read more

Species of the common discomycete genus Bisporella reassigned to at least four genera

Mitchell, J.K., et al., 2022. Species of the common discomycete genus Bisporella reassigned to at least four genera. Mycologia. Publisher's VersionAbstract
Bisporella as typically conceived is a genus of noticeable, bright yellow inoperculate discomycetes. This interpretation of the genus, however, is at odds with Bisporella pallescens, the current name of the type species of the genus; furthermore, the genus has been interpreted as including the unusual species Bisporella resinicola. By comparing morphological and molecular traits of species traditionally included in Bisporella, we show that the genus is polyphyletic, with many “typical” members of the genus belonging instead in Calycina in Pezizellaceae. Bisporella pallescens is conclusively linked with its asexual morph, Bispora antennata, and the genus Bisporella is abandoned as a later synonym of the monotypic genus Bispora (previously applied only to asexual fungi) and placed as sister to Hymenoscyphus in Helotiaceae. Bisporella resinicola is shown to represent an independent monotypic genus, Eustilbum, which so far is placed incertae sedis in Helotiales. Finally, “Bisporella” subpallida, like Bispora, belongs to Helotiaceae but is instead related to “Phaeohelotium” epiphyllum.
Read more

A reexamination and realignment of Peziza sensu lato (Pezizomycetes) species in southern South America/Un reexamen y revisión de las especies de Peziza sensu lato (Pezizomycetes) en el cono sur de Sudamérica

Pfister, D.H., et al., 2022. A reexamination and realignment of Peziza sensu lato (Pezizomycetes) species in southern South America/Un reexamen y revisión de las especies de Peziza sensu lato (Pezizomycetes) en el cono sur de Sudamérica. Darwiniana , 10 (1) , pp. 148-177. Publisher's VersionAbstract

In this study we review recent collections and historical records of epigeous members of the Pezizales formerly placed in the large, heterogenous genus Peziza from temperate southern South America. Recent analyses using molecular phylogenetic methods allow placement of these species in several previously described genera in recognition of the heterogeneity of Peziza. We include species in nine genera, describe one new species (Peziza gamundiae sp. nov.), and propose one new combination (Phylloscypha nothofageti comb. nov.). We also demonstrate that Pustularia microspora is a synonym of the previously described taxon Peziza pseudosylvestris. Our purpose is to draw attention to these taxa in order to promote their collection and study in a modern framework.

En este trabajo hemos revisado material fresco y colecciones históricas de Pezizales epigeos formalmente incluidos en el amplio y heterogéneo género Peziza provenientes de las zonas templadas del sur de Sudamérica. Estudios recientes basados en filogenias moleculares han permitido posicionar estas especies en varios géneros previamente descritos demostrando su heterogeneidad. Incluimos aquí especies de nueve géneros, una especie nueva para la ciencia (Peziza gamundiae sp. nov.) y proponemos una nueva combinación (Phylloscypha nothofageti comb. nov.). También demostramos que Pustularia microspora es sinónimo de un taxón previamente descrito como Peziza pseudosylvestris. Nuestro objetivo es llamar la atención sobre la presencia de estos taxa para promover su recolección y estudio en trabajos científicos modernos.

Read more

Exploration of Marine Lichenized Fungi as Bioindicators of Coastal Ocean Pollution in the Boston Harbor Islands National Recreation Area

Nokes, L.F., Haelewaters, D. & ., P.D.H., 2022. Exploration of Marine Lichenized Fungi as Bioindicators of Coastal Ocean Pollution in the Boston Harbor Islands National Recreation Area. Rhodora , 122 (992) , pp. 251–273. Publisher's VersionAbstract
This preliminary exploration of marine lichenized fungi (lichens) as bioindicators of water pollution examined the distribution of intertidal lichen communities in the Boston Harbor Islands National Recreation Area with respect to recorded pollution throughout the harbor. We found significant negative associations between pollution measurements and the health of the lichen community based on cover and species richness. We also observed significant differences in species composition between areas of higher pollution and areas of lower pollution, though not enough data are available to establish the pollution sensitivity or tolerance of individual species. We note that difficulties in the collection and identification of marine lichens hamper efforts to use them broadly as bioindicators. This study suggests that marine lichens could prove useful as bioindicators, but more research is needed to understand the differential effects of pollution on individual species as well as to establish practical procedures both for quantifying marine lichen community health and for widespread bioindication using marine lichens. Finally, one species collected during this study, Verrucaria ceuthocarpa, represents a first report for the Boston Harbor Islands National Recreation Area.
Read more

Powdery mildews on Quercus: A worldwide distribution and rediscovered holotype provide insights into the spread of these ecologically important pathogens

Bradshaw, M., Braun, U. & Pfister, D.H., 2022. Powdery mildews on Quercus: A worldwide distribution and rediscovered holotype provide insights into the spread of these ecologically important pathogens. Forest Pathology. Publisher's VersionAbstract
Powdery mildew, caused by Erysiphe spp., on oak has been shown to have serious ecological consequences on Quercus hosts. Erysiphe alphitoides and Equercicola are two of the most heavily studied and common powdery mildews known to occur on Quercus species. In recent years, these species have been noted throughout the world on a range of hosts within and outside the Quercus genus. Reports that Ealphitoides was absent in European herbaria before 1921 and the discovery of the holotype of Ealphitoides from 1911 in an American herbarium (FH) led to the current study in which we genetically analysed six specimens of Ealphitoides s. lat including, most importantly, the holotype of Ealphitoides from France collected in 1911. The results of our analyses revealed that: (1) The sequence of the Ealphitoides holotype falls within the Equercicola clade, confirming that Ealphitoides did not spread to Europe until ~1921. (2) Ealphitoides var. chenii forms a monophyletic clade with Eepigena and should be reduced to synonymy with that species and (3) through sequence analyses Ealphitoides and Equercicola are confirmed to have spread to North America. The sequencing results of the Ealphitoides holotype have severe nomenclatural-taxonomic consequences. A proposal was submitted simultaneously with the present manuscript to conserve the name Ealphitoides so that the traditional usage of the names Ealphitoides and Equercicola could be maintained. The sequences obtained for the current study provide new insight into the taxonomy and spread of these ecologically significant, globally distributed species. The present study highlights the importance of sequencing specimens from type material, above all when morphological similar species are involved.
Read more
More