MOLECULAR EVIDENCE THAT THE ASEXUAL INDUSTRIAL FUNGUS TRICHODERMA-REESEI IS A CLONAL DERIVATIVE OF THE ASCOMYCETE HYPOCREA-JECORINA

The relationship of the important cellulase producing asexual fungus T richoderma reesei to its putative teleomorphic (sexual) ancestor Hypoc rea jecorina and other species of the Trichoderma sect. Longibrachiatu m was studied by PCR-fingerprinting and sequence analyses of the nucle ar ribosomal DNA region containing the internal transcribed spacers (I TS-1 and ITS-2) and the 5.8S rRNA gene. The differences in the corresp onding ITS sequences allowed a grouping of anamorphic (asexual) specie s of Trichoderma sect. Longibrachiatum into Trichoderma longibrachiatu m, Trichoderma pseudokoningii, and Trichooderma reesei. The sexual spe cies Hypocrea schweinitzii and H. jecorina were also clearly separated from each other. H. jecorina and T. reesei exhibited identical sequen ces, suggesting close relatedness or even species identity. Intraspeci fic and interspecific variation in the PCR-fingerprinting patterns sup ported the differentiation of species based on ITS sequences, the grou ping 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 of H. jecorina, but much lower than the observed interspecific variations. Identical I TS sequences and the high similarity of PCR-fingerprinting patterns in dicate a very close relationship between T. reesei and H. jecorina, wh ereas differences of the ITS sequences and the PCR-fingerprinting patt erns show a clear phylogenetic distance between T. reesei/H.jecorina a nd T. longibrachiatum. T. reesei is considered to be an asexual, clona l line derived from a population of the tropical ascomycete H. jecorin a.