The relationship of the important cellulase producing asexual fungus Trichoderma reesei to its putative teleomorphic (sexual) ancestor Hypocrea jecorina and other species of the Trichoderma sect. Longibrachiatum was studied by PCR-fingerprinting and sequence analyses of the nuclear ribosomal DNA region containing the internal transcribed spacers (ITS-1 and ITS-2) and the 5.8S rRNA gene. The differences in the corresponding ITS sequences allowed a grouping ofanamorphic (asexual) species of Trichoderma sect. Longibrachiatum into Trichoderma longibrachiatum, Trichoderma pseudokoningii, and Trichoderma reesei. The sexual species Hypocrea schweinitzii and H. jecorina were also clearly separated from each other. H. jecorina and T. reesei exhibited identical sequences, suggesting close relatedness or even species identity. Intraspecific and interspecific variation in the PCR-fingerprinting patterns supported the differentiation of species based on ITS sequences, the grouping of the strains, and the assignment of these strains to individual species. The variations between T. reesei and H. jecorina were at the same order of magnitude as found between all strains ofH.jecorina, but much lower than the observed interspecific variations. Identical ITS sequences and the high similarity of PCRfingerprinting patterns indicate a very close relationship between T. reesei and H. jecorina, whereas differences of the ITS sequences and the PCR-fingerprinting patterns show a clear phylogenetic distance between T. reesei/H. jecorina and T. longibrachiatum. T. reesei is considered to be an asexual, clonal line derived from a population of the tropical ascomycete H. jecorina.Trichoderma reesei is an asexually reproducing filamentous fungus. Isolated in the Solomon Islands during World War II from cotton canvas, the species is unique because it is known only from a single isolate (QM6a). This isolate is renowned for its high ability to produce cellulases and it is the sole progenitor of the many mutants currently in use (1). T reesei is not known to undergo recombination through meiosis. Many deuteromycetes are permanently sexually incompetent (2, 3) and possibly clonal derivatives of life cycles that once included a meiosis, some aspect of an outcrossing mating system having been perturbed. Because Trichoderma is a genus of special economic interest-individual species are used in biological control (4, 5), in the production of cellulolytic and other hydrolytic enzymes (6, 7), and in antibiotics (8)-the identification of a teleomorph (sexual state) would be useful. The ability to recover meiotic progeny would provide a means to study biological properties using classical genetics, an approach that has proven invaluable in the study of the molecular biology of Neurospora crassa and Aspergillus nidulans (9). Further, teleomorphs are powerful predictors of taxonomic relationships, and related species can be expected to possess similar biological abilities. The question thus arises whether T. reesei, and many other fungi of economic i...

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We have used the techniques of DNA fingerprinting and polymerase chain reaction (PCR) with probes specific for hypervariable repetitive DNA sequences (mini- and microsatellite DNAs) to analyze 36 yeast strains belonging to 10 species and 2 genera. Using (GTG)5, (GACA)4, phage M13 DNA and the M13 sequence GAGGGTGGCGGTTCT as probes and primers, respectively, we obtained DNA polymorphisms which allowed us to discriminate 23 biotechnologically important strains of the yeast Saccaromyces cerevisiae and to distinguish them from strains of S. pastorianus, S. bayanus and S. willianus. Our results demonstrate that both DNA and PCR fingerprinting are suitable tools for an easy, fast and reliable molecular typing of yeasts. The DNA fingerprinting method seems to be more sensitive than PCR fingerprinting with respect to the individualization of strains. Nevertheless, using the PCR fingerprinting technique we were able to unambigously discriminate between genotypes of different species. Therefore, PCR fingerprinting might become a useful tool in the classification of yeasts on the basis of phylogenetic relatedness.

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Trichoderma (Ascomycetes,Hypocreales) strains that have warted conidia are traditionally identified as T. viride, the type species ofTrichoderma. However, two morphologically distinct types of conidial warts (I and II) have been found. Because each type corresponds to a unique mitochondrial DNA pattern, it has been questioned whether T. viride comprises more than one species. Combined molecular data (sequences of the internal transcribed spacer 1 [ITS-1] and ITS-2 regions and of part of the 28S rRNA gene along with results of restriction fragment length polymorphism analysis of the endochitinase gene and PCR fingerprinting), morphology, physiology, and colony characteristics distinguish type I and type II as different species. Type I corresponds to “true” T. viride, the anamorph of Hypocrea rufa. Type II represents a new species, T. asperellum, which is, in terms of molecular characteristics, close to the neotype of T. hamatum.