Can older fungal sequence data be useful?

This chapter focuses primarily on the use and evaluation of fungal nucleotide sequences to obtain information that can be used to elucidate relationships between strains and specimens. The importance of the reexamination and evaluation of older material in order to identify new species derived from existing taxa that had previously been considered under wider concepts or acknowledged as species complexes is also discussed.

Fungal Composition and Diversity of the Tobacco Leaf Phyllosphere during Curing of Leaves

Background: Rhizopus oryzae causes tobacco pole rot in China during tobacco flue-curing. Flue-curing is a post-harvest process done to prepare tobacco leaves and involves three different stages: the yellowing stage has the lowest temperatures and highest humidity, then the color-fixing stage has higher temperatures and medium humidity, and finally the stem-drying stage has the highest temperatures and lowest humidity.Results: In this study, fungal culturing and IonS5TMXL high-throughput sequencing techniques were used to reveal the fungal community of the petioles and lamina of tobacco leaves infected with pole rot during flue-curing. A total of 108 fungal isolates belonging to 5 genera and 10 species were isolated on media. The most common fungi isolated was R. oryzae, most often found equally on petioles and laminas in the color-fixing stage, followed by saprotrophs, mostly Aspergillus fumigatus and Aspergillus flavus. High-throughput sequencing revealed saprotrophs, Alternaria being the most abundant genus, followed by Phoma, Cercospora and Aspergillus, whereas Rhizopus was the tenth most abundant genus, which was mostly found on petioles at the yellowing stage. Both culturable fungal diversity and fungal sequence diversity was higher at stem-drying stage than the yellowing and color-fixing stages, and diversity was higher with leaf lamina than petioles revealing that the changes in fungal composition and diversity during the curing process were similar with both methods.Conclusions: A better understanding of the saprotrophic fungi during curing of leaves with pole rot could result in the identification of highly competitive saproptrophs that may act as potential biocontrol agents of tobacco pole rot.

The UNITE Database for Molecular Identification and for Communicating Fungal Species

UNITE (https://unite.ut.ee; Nilsson et al. 2018) is an international community of scientists and citizen scientists established in 2001. The ambition of UNITE is to develop: 1) datasets and tools for robust and reproducible molecular identification; 2) Persistent Identifiers based system for the communicating fungal species. Datasets of the nuclear ribosomal internal transcribed spacer (ITS) region, form the basis for UNITE. The current version includes nearly 1 million public fungal ITS sequences. Datasets are curated and annotated by community members. During the past 15 years, they made more than 275 000 improvements. In the complete absence of Latin names for species, UNITE offers a unique system where species hypotheses (SH) are provided with Digital Object Identifiers (DOIs). The current version 8 of UNITE offers more than 800 000 DOI-based SHs. One such SH DOI page is shown in Fig. 1. These DOI identifiers are also incorporated into the taxonomic backbone, making communication of taxa seamless in both directions. DOI identifiers of species hypotheses are also used by GBIF (Global Biodiversity Information Facility) in order to publish high-throughput sequencing taxon occurrence data in their data portal. UNITE serves as a data provider for a range of metabarcoding software pipelines and regularly exchanges data with all major fungal sequence databases and other community resources. Recent improvements include ITS-based species hypotheses for all eukaryotes and aggregation of full-length, high-quality ITS sequences generated by the PacBio Sequel system (https://www.pacb.com/products-and-services/sequel-system) from diverse material samples.

Arbuscular mycorrhizal fungi assemblages in Chernozem great groups revealed by massively parallel pyrosequencing

The arbuscular mycorrhizal (AM) fungal resources present in wheat fields of the Canadian Prairie were explored using 454 pyrosequencing. Of the 33 dominant AM fungal operational taxonomic units (OTUs) found in the 76 wheat fields surveyed at anthesis in 2009, 14 clustered as Funneliformis – Rhizophagus, 16 as Claroideoglomus, and 3 as Diversisporales. An OTU of Funneliformis mosseae and one OTU of Diversisporales each accounted for approximately 16% of all AM fungal OTUs. The former was ubiquitous, and the latter was mainly restricted to the Black and Dark Brown Chernozems. AM fungal OTU community composition was better explained by the Chernozem great groups (P = 0.044) than by measured soil properties. Fifty-two percent of the AM fungal OTUs were unrelated to measured soil properties. Black Chernozems hosted the largest AM fungal OTU diversity and almost twice the number of AM fungal sequences seen in Dark Brown Chernozems, the great group ranking second for AM fungal sequence abundance. Brown Chernozems hosted the lowest AM fungal abundance and an AM fungal diversity as low as that seen in Gray soils. We concluded that Black Chernozems are most conducive to AM fungal proliferation. AM fungi are generally distributed according to Chernozem great groups in the Canadian Prairie, although some taxa are evenly distributed in all soil groups.