The first 100 Trichoderma species characterized by molecular data

Trichoderma species are generally abundant on decaying wood and in soil because of their success in various heterotrophic interactions, including decomposition, parasitism, and even opportunistic endophytism. Many Trichoderma species or, precisely, many individual Trichoderma strains, have various important applications in industry and human life, which led to the inclusion of Hypocrea jecorina (Trichoderma reesei), the well-known producer of industrial enzymes, in the list of organisms whose genomes have been sequenced. Trichoderma species also have been adopted as agents of biological control of plant pathogenic fungi and as antibiotic producers. Trichoderma longibrachiatum is known as an opportunistic pathogen of immunocompromised mammals, including humans, and some species are common indoor contaminants. Given these properties, correct identification at the species level is highly desirable. However, within the past decade, the number of recognized Trichoderma species has tripled, reaching 100. Therefore, Trichoderma taxonomy and species identification is a difficult issue. The abundant homoplasy in phenetic characters is likely the reason, given that the number of morphologically distinct species is significantly lower than the number of phylogenetically distinct species recognized using methods of gene sequence analysis. In this review, we introduce to the scientific community the development of modern tools for Trichoderma species identification: the oligonucleotide barcode program TrichOKEY version 1.0, and TrichoBLAST, the multilocus database of vouchered sequences powered by a similarity search tool. We also discuss the application of the Genealogic Concordance Phylogenetic Species Recognition approach. In combination, these advances make it possible to identify all known Trichoderma species based on sequence analysis.