Showing papers by "Joyce E. Longcore published in 2020"

Survey of Early-Diverging Lineages of Fungi Reveals Abundant and Diverse Mycoviruses.

Abstract: Mycoviruses are widespread and purportedly common throughout the fungal kingdom, although most are known from hosts in the two most recently diverged phyla, Ascomycota and Basidiomycota, together called Dikarya. To augment our knowledge of mycovirus prevalence and diversity in underexplored fungi, we conducted a large-scale survey of fungi in the earlier-diverging lineages, using both culture-based and transcriptome-mining approaches to search for RNA viruses. In total, 21.6% of 333 isolates were positive for RNA mycoviruses. This is a greater proportion than expected based on previous taxonomically broad mycovirus surveys and is suggestive of a strong phylogenetic component to mycoviral infection. Our newly found viral sequences are diverse, composed of double-stranded RNA, positive-sense single-stranded RNA (ssRNA), and negative-sense ssRNA genomes and include novel lineages lacking representation in the public databases. These identified viruses could be classified into 2 orders, 5 families, and 5 genera; however, half of the viruses remain taxonomically unassigned. Further, we identified a lineage of virus-like sequences in the genomes of members of Phycomycetaceae and Mortierellales that appear to be novel genes derived from integration of a viral RNA-dependent RNA polymerase gene. The two screening methods largely agreed in their detection of viruses; thus, we suggest that the culture-based assay is a cost-effective means to quickly assess whether a laboratory culture is virally infected. This study used culture collections and publicly available transcriptomes to demonstrate that mycoviruses are abundant in laboratory cultures of early-diverging fungal lineages. The function and diversity of mycoviruses found here will help guide future studies into mycovirus origins and ecological functions.IMPORTANCE Viruses are key drivers of evolution and ecosystem function and are increasingly recognized as symbionts of fungi. Fungi in early-diverging lineages are widespread, ecologically important, and comprise the majority of the phylogenetic diversity of the kingdom. Viruses infecting early-diverging lineages of fungi have been almost entirely unstudied. In this study, we screened fungi for viruses by two alternative approaches: a classic culture-based method and by transcriptome-mining. The results of our large-scale survey demonstrate that early-diverging lineages have higher infection rates than have been previously reported in other fungal taxa and that laboratory strains worldwide are host to infections, the implications of which are unknown. The function and diversity of mycoviruses found in these basal fungal lineages will help guide future studies into mycovirus origins and their evolutionary ramifications and ecological impacts.

The Collection of Zoosporic Eufungi at the University of Michigan (CZEUM): introducing a new repository of barcoded Chytridiomyceta and Blastocladiomycota cultures

Abstract: We formed the Collection of Zoosporic Eufungi at the University of Michigan (CZEUM) in 2018 as a cryopreserved fungal collection consolidating the University of Maine Culture Collection (UMCC, or JEL), the University of Alabama Chytrid Culture Collection (UACCC), and additional zoosporic eufungal accessions. The CZEUM is established as a community resource containing 1045 cryopreserved cultures of Chytridiomycota, Monoblepharidomycota, and Blastocladiomycota, with 52 cultures being ex-type strains. We molecularly characterized 431 cultures by amplifying the majority of the rDNA operon in a single reaction, yielding an average fragment length of 4739 bp. We sequenced multiplexed samples with an Oxford Nanopore Technology MinION device and software, and demonstrate the method is accurate by producing sequences identical to published Sanger sequences. With these data, we generated a phylogeny of 882 zoosporic eufungi strains to produce the most comprehensive phylogeny of these taxa to date. The CZEUM is thus largely characterized by molecular data, which can guide instructors and researchers on future studies of these organisms. Cultures from the CZEUM can be purchased through an online portal.

Quaeritorhiza haematococci is a new species of parasitic chytrid of the commercially grown alga, Haematococcus pluvialis.

Abstract: Aquaculture companies grow the green alga Haematococcus pluvialis (Chlorophyta) to extract the carotenoid astaxanthin to sell, which is used as human and animal dietary supplements. We were requested to identify an unknown pathogen of H. pluvialis from an alga growing facility in the southwestern United States. To identify this zoosporic fungus and determine its phylogenetic placement among other chytrids, we isolated it into pure culture, photographed its morphology and zoospore ultrastructure, and sequenced and analyzed portions of nuc rDNA 18S and 28S genes. The organism belongs in the Chytridiomycota, but a comparison of rDNA with available representatives of the phylum did not convincingly place it in any described order. The unique zoospore ultrastructure supports its indeterminate ordinal position, and the morphology, as determined by light microscopy, did not match any described species. Consequently, we have placed this chytrid in the new genus, Quaeritorhiza, and described it as the new species Q. haematococci in the family Quaeritorhizaceae but otherwise incertae sedis in the Chytridiomycetes. This new taxon is important because it increases the known diversity of Chytridiomycota and the organism has the ability to disrupt agricultural production of an algal monoculture.

Donald John Stoddart Barr, 18 September 1937-20 November 2018.

Abstract: Donald John Stoddart Barr (FIG. 1) was born on September 18, 1937, and grew up in wartime England near Guildford in Surrey. With a large garden, forests, and fields around his country home, Donald,...