The internal transcribed spacer (ITS) region of the nuclear ribosomal repeat unit is the most popular locus for species identification and subgeneric phylogenetic inference in sequence-based mycological research. The region is known to show certain variability even within species, although its intraspecific variability is often held to be limited and clearly separated from interspecific variability. The existence of such a divide between intra- and interspecific variability is implicitly assumed by automated approaches to species identification, but whether intraspecific variability indeed is negligible within the fungal kingdom remains contentious. The present study estimates the intraspecific ITS variability in all fungi presently available to the mycological community through the international sequence databases. Substantial differences were found within the kingdom, and the results are not easily correlated to the taxonomic affiliation or nutritional mode of the taxa considered. No single unifying yet stringent upper limit for intraspecific variability, such as the canonical 3% threshold, appears to be applicable with the desired outcome throughout the fungi. Our results caution against simplified approaches to automated ITS-based species delimitation and reiterate the need for taxonomic expertise in the translation of sequence data into species names.

https://journals.sagepub.com/doi/pdf/10.4137/EBO.S653

Intraspecific ITS Variability in the Kingdom Fungi as Expressed in the International Sequence Databases and Its Implications for Molecular Species Identification

Colletotrichum - current status and future directions.

Fungi of the genus Trichoderma are soilborne, green-spored ascomycetes that can be found all over the world. They have been studied with respect to various characteristics and applications and are known as successful colonizers of their habitats, efficiently fighting their competitors. Once established, they launch their potent degradative machinery for decomposition of the often heterogeneous substrate at hand. Therefore, distribution and phylogeny, defense mechanisms, beneficial as well as deleterious interaction with hosts, enzyme production and secretion, sexual development, and response to environmental conditions such as nutrients and light have been studied in great detail with many species of this genus, thus rendering Trichoderma one of the best studied fungi with the genome of three species currently available. Efficient biocontrol strains of the genus are being developed as promising biological fungicides, and their weaponry for this function also includes secondary metabolites with potential applications as novel antibiotics. The cellulases produced by Trichoderma reesei, the biotechnological workhorse of the genus, are important industrial products, especially with respect to production of second generation biofuels from cellulosic waste. Genetic engineering not only led to significant improvements in industrial processes but also to intriguing insights into the biology of these fungi and is now complemented by the availability of a sexual cycle in T. reesei/Hypocrea jecorina, which significantly facilitates both industrial and basic research. This review aims to give a broad overview on the qualities and versatility of the best studied Trichoderma species and to highlight intriguing findings as well as promising applications.

/pdf/biology-and-biotechnology-of-trichoderma-2kdws1fdv1.pdf

Biology and biotechnology of Trichoderma

Structural and functional genomics investigations are making an important impact on the current understanding and application of microbial agents used for plant disease control. Here, we review the case of Trichoderma spp., the most widely applied biocontrol fungi, which have been extensively studied using a variety of research approaches, including genomics, transcriptomics, proteomics, metabolomics, etc. Known for almost a century for their beneficial effects on plants and the soil, these fungi are the subject of investigations that represent a successful case of translational research, in which 'omics-generated novel understanding is directly translated in to new or improved crop treatments and management methods. We present an overview of the latest discoveries on the Trichoderma expressome and metabolome, of the complex and diverse biotic interactions established in nature by these microbes, and of their proven or potential importance to agriculture and industry.

/pdf/translational-research-on-trichoderma-from-omics-to-the-37g7gqnwbi.pdf

Translational Research on Trichoderma: From 'Omics to the Field

Fungi are morphologically, ecologically, metabolically, and phylogenetically diverse. They are known to produce numerous bioactive molecules, which makes them very useful for natural products researchers in their pursuit of discovering new chemical diversity with agricultural, industrial, and pharmaceutical applications. Despite their importance in natural products chemistry, identification of fungi remains a daunting task for chemists, especially those who do not work with a trained mycologist. The purpose of this review is to update natural products researchers about the tools available for molecular identification of fungi. In particular, we discuss (1) problems of using morphology alone in the identification of fungi to the species level; (2) the three nuclear ribosomal genes most commonly used in fungal identification and the potential advantages and limitations of the ITS region, which is the official DNA barcoding marker for species-level identification of fungi; (3) how to use NCBI-BLAST search for DNA barcoding, with a cautionary note regarding its limitations; (4) the numerous curated molecular databases containing fungal sequences; (5) the various protein-coding genes used to augment or supplant ITS in species-level identification of certain fungal groups; and (6) methods used in the construction of phylogenetic trees from DNA sequences to facilitate fungal species identification. We recommend that, whenever possible, both morphology and molecular data be used for fungal identification. Our goal is that this review will provide a set of standardized procedures for the molecular identification of fungi that can be utilized by the natural products research community.

Fungal Identification Using Molecular Tools: A Primer for the Natural Products Research Community

An oligonucleotide barcode for species identification in Trichoderma and Hypocrea.

The holomorph of the new species Hypocrea voglmayrii (Hypocreales, Ascomycota, Fungi) is described by a combined approach, using morphology of the teleomorph, morphology of the anamorph, culture studies and phylogenetic analyses of ITS1 and 2, ech42 and rpb2 gene sequences. Its anamorph Trichoderma voglmayrii is described as a new anamorph species. Unlike most other species of Hypocrea the teleomorph of H. voglmayrii occurs on dry standing trunks and exhibits well defined black ostioles. Although exclusively collected at higher altitudes, this species grows at 35 C in culture. Hypocrea voglmayrii develops pale yellowish to greenish conidia, a yellowish pigment and a coconut-like odor on CMD. Phylogenetically, H. voglmayrii forms a distinct, isolated branch between the section Trichoderma and the H. pachybasioides clade but does not associate with any of these clades in different gene trees.

Hypocrea voglmayrii sp. nov. from the Austrian Alps represents a new phylogenetic clade in Hypocrea/Trichoderma

TrichoBLAST: a multilocus database for Trichoderma and Hypocrea identifications

The new species Hypocrea crystalligena (Hypocreales, Ascomycota, Fungi) is described as a holomorph and characterized based on an integrated phenotypic and phylogenetic approach, using teleomorph and anamorph morphologies, culture studies and analyses of phylogenetic markers including internal transcribed spacer 1 and 2 (ITS1 and 2), two last introns of the translation elongation factor 1-alpha encoding gene (tef1), and a portion of the rpb2 gene, encoding the second largest RNA polymerase subunit. Stromata of H. crystalligena show similarities with those of species from Trichoderma sect. Trichoderma but differ in several respects, including color, presence of white crystals on the surface and small ascospores. Colonies on CMD appear distinct, form colorless to white crystals on isolation, a yellowish to brown pigment and an anamorph with hyaline conidia exhibiting verticillium-like to gliocladium-like structural elements. ITS1 and 2 sequences exhibit all genus-specific features but also contain several unique hallmarks permitting development of a species-diagnostic barcode. Based on the analyses of partial rpb2 and tef1 sequences, H. crystalligena constitutes a separate evolutionary lineage with H. megalocitrina and H. psychrophila as its nearest neighbors. All these species form one phylogenetic clade with the H. pulvinata/H. citrina node.

Monika Komon

Papers

An oligonucleotide barcode for species identification in Trichoderma and Hypocrea.

Hypocrea voglmayrii sp. nov. from the Austrian Alps represents a new phylogenetic clade in Hypocrea/Trichoderma

TrichoBLAST: a multilocus database for Trichoderma and Hypocrea identifications

Hypocrea crystalligena sp. nov., a common European species with a white-spored Trichoderma anamorph.