Phylogenetic relationships of Trichoderma harzianum causing mushroom green mold in Europe and North America to other species of Trichoderma from world-wide sources

摘要

Nucleotide sequences of internal transcribed spacers (ITS-1 and ITS-2) and the 5.8 S gene of the ribosomal DNA repeat were examined in 15 lines of Trichoderma spp. Six lines representing 4 biotypes (Th1, Th2, Th3 and Th4) of T. harzianum associatedwith mushroom compost or the raw materials used in compost could be separated into 2 distinct groups. One group contained biotypes Th1, Th2 and Th4 while the other contained biotype Th3 and other isolates of T. harzianum/atroviride from worldwide sources. It was proposed that Th3 should be considered T. atroviride and not T. harzianum. Within this group, excluding gaps, nucleotide differences in ITS-1 were as much as double those of the ITS-2 region (25.6% versus 11.0%, respectively). Biotype Th3 from Ireland accounted for most of the variation in both the ITS-1 (24.3%) and ITS-2 (7.8%) data. Five nucleotide substitutions (2.5%) were found in ITS-1 sequences for the most prevalent biotypes associated with mushroom green mold (Th2 and Th4) from Canada,Ireland and the United States. Only 1 substitution (0.5%) was found for these biotypes for ITS-2. Four nucleotide substitutions (2.0%) were found for Th2 from Ireland compared to isolates of biotype Th4 from Canada and the United States. Only 1 nucleotide difference (0.5%) each for ITS-1 and ITS-2 was found among the isolates of Th4 from Canada and the United States. Thus, most of the variation in nucleotide sequences among the biotypes were present in ITS-1. Finally, Th2 accounted for the only difference found in the 5.8 S rDNA sequences of the 6 lines of mushroom-associated T. harzianum.