Phytopathogenic Filamentous (Ashbya, Eremothecium) and Dimorphic Fungi (Holleya, Nematospora) with Needle-shaped Ascospores as New Members Within the Saccharomycetaceae

Abstract

Phylogenetic relationships between species from the genera Kluyveromyces and Saccharomyces and representatives of the Metschnikowiaceae (Holleya, Metschnikowia, Nematospora) including the two filamentous phytopathogenic fungi Ashbya gossypii and Eremothecium ashbyii were studied by comparing the monosaccharide pattern of purified cell walls, the ubiquinone system, the presence of dityrosine in ascospore walls, and nucleotide sequences of ribosomal DNA (complete 18S rDNA, ITS1 and ITS2 region). Based on sequence information from both ITS regions, the genera Ashbya, Eremothecium, Holleya and Nematospora are closely related and may be placed in a single genus as suggested by Kurtzman (1995; J. Industr. Microbiol. 14, 523–530). In a phylogenetic tree derived from the ITS1 and ITS2 region as well as in a tree derived from the complete 18S rDNA gene, the genus Metschnikowia remains distinct. The molecular evidence from ribosomal sequences suggests that morphology and ornamentation of ascospores as well as mycelium formation and fermentation should not be used as differentiating characters in family delimitation. Our data on cell wall sugars, ubiquinone side chains, dityrosine, and ribosomal DNA sequences support the inclusion of plant pathogenic, predominantly filamentous genera like Ashbya and Eremothecium or dimorphic genera like Holleya and Nematospora with needle‐shaped ascospores within the family Saccharomycetaceae. After comparison of sequences from the complete genes of the 18S rDNA the genus Kluyveromyces appears heterogeneous. The type species of the genus, K. polysporus is congeneric with the genus Saccharomyces. The data of Cai et al. (1996; Int. J. Syst. Bacteriol. 46, 542–549) and our own data suggest to conserve the genus Kluyveromyces for a clade containing K. marxianus, K. dobzhanskii, K. wickerhamii and K. aestuarii, which again can be included in the family Saccharomycetaceae. The phylogenetic age of the Metschnikowiaceae and Saccharomycetaceae will be discussed in the light of coevolution. © 1997 John Wiley & Sons, Ltd.

Transcriptome sequencing of Mycosphaerella fijiensis during association with Musa acuminata reveals candidate pathogenicity genes

“…Dityrosine is a cross-linking agent that is present in the cell walls of some fungi and protects against adverse environmental conditions [75, 76]. Dityrosine is present in the outermost wall layer of ascospores in many members of the family Saccharomycetaceae [77]. In Candida albicans , dityrosine is also produced along the surface of yeast bud scars and germinated cells [78].…”

Optimized sample preparation for single-molecule localization-based superresolution microscopy in yeast

“…However, S. cerevisiae with an intact cell wall can be immobilized on coverslips coated with a thin layer of Con A 16 . This carbohydratebinding protein, which is a lectin extracted from jack-beans, interacts with sugar residues (mannosyl or glycosyl) on the cell wall proteins of S. cerevisiae 35 .…”

“…Note that the composition of cell wall glycans can differ substantially within and between yeast families 35 , so a different lectin may be needed for immobilization of other yeast cells.…”

Septation and cytokinesis in fungi

“…This centers around the questions whether hyphal growth is an ancient trait over yeast-like growth and if hyphal growth may have evolved independently several times. With our current knowledge we find that the closest relative to A. gossypii within the hemiascomycetous yeasts is the dimorphic plant pathogen Holleya sinecauda (Prillinger et al, 1997). This may open the possibility of an evolutionary developmental genetics approach to morphogenesis within this group of fungi (Schade et al, 2003).…”