Molecular phylogeny, teleomorph identification and habitat preference of Trichoderma with particular emphasis on species used in biological control

Trichoderma and Gliocladium are common soil saprophytes which can use a wide range of compounds as carbon and nitrogen sources, and are thus and usually cultivatable on inexpensive, simple formulated substrates which makes certain isolates attractive candidates for a variety of biological control applications. However, many Trichoderma strains are usually effective only against a single or few pathogens; furthermore, several strains do not attack only plant pathogens but also cultivated mushrooms. In addition, some Trichoderma strains have been reported to promote plant growth, and others have been reported to be pathogenic to plants. Finally, while Trichoderma and Gliocladium are generally not considered as pathogens for humans, some cases of infection have been noted under exceptional conditions in humans as well as in animals. For an application as a biocontroi agent, however, it will be necessary to predict and control the behavior of the organism in the environment, in order to exclude any unwanted (particularly harmful) side effects. It is also necessary to elucidate details of its biology, lifecycle and pathogenecity. Furthermore, some countries (e.g. Australia) require that the teleomorph-anamorph relationship for a biocontrol agent must be clarified before it can be considered for release by the quarantine officials. All these requirements are currently hampered by the poor state of taxonomy and identification of - individual species of Trichoderma, which frequently leads to misidentifications. Current taxonomic systems based on morphological characters are difficult to use because of the paucity of morphological characters and their seeming plasticity. The present project application is based on preliminary results from our laboratory, in which molecular tools (i.e. the sequence of one intergenic spacer region of the nuclear ribosomal DNA cluster) had been used to set up a molecular taxonomic system of Trichoderma. The data suggested that the relatively narrow species concepts currently used for Trichoderma sections Pachybasium and section Trichoderma may still be too broad, and that morphological or cultural attributes, such as the sterile conidiophore elongations, their tuberculation, or conidial colour - while undoubtedly useful to distinguish isolates - may not reflect true phylogenetic relationships in Trichoderma. In order to set up a reliable and unequivocal taxonomic system for Trichoderma, the present proposal aims at an investigation of the reliability of the intergenic spacer regions for Trichoderma taxonomy. and at the establishment of a systematics based on sequence analys%We trust that the results from this project should not only lead to a safe concept for definition of species within Trichoderma, but also yield information on their occurrence in nature.

Filamentous fungi of the genus Trichoderma are ubiquitous soil colonizers, where they participate in the degradation of plant polymers and detoxification of xenobiotics. Some of ist members are also used by the biotechnological industry in the production of enzymes, antibiotics, pharmaca, volatiles, and biological control agents. Idnetification of these fungi by traditional (morphological means ) has been proven difficult due to a paucity of overlapping characters. The aikm of this project therefore was to use and develop molecular tools for the identification of these fungi at the species level, and to use these methods subsequently for assessing the genetic stability and species identity of isolates used in biotechnology. The respective results showed that the various species differed considerably with respect to their genetic stability, and also with respect to their biochemical properties. Species identity of half of the isolates used in biocontrol was incorrect. In an investigation of biodiversity of the isolates from Central Asia and South-East Asia, about 15 % of the isolates turned out to be new species. The results from this project can be used for targetted screening of jstrains to be used for various purposes.