Role of the Trichoderma harzianum endochitinase gene, ech42, in mycoparasitism

The role of the Trichoderma harzianum endochitinase (Ech42) in mycoparasiti sm was studied by genetically manipulating the gene that encodes Ech42, ech 42, We constructed several transgenic T. harzianum strains carrying multipl e copies of ech42 and the corresponding gene disruptants, The level of extr acellular endochitinase activity when T. harzianum was grown under inducing conditions increased up to 42-fold in multicopy strains as compared with t he wild type, whereas gene disruptants exhibited practically no activity. T he densities of chitin labeling of Rhizoctonia solani cell walls, after int eractions with gene disruptants were not statistically significantly differ ent than the density of chitin labeling after interactions with the wild ty pe. Finally, no major differences in the efficacies of the strains generate d as biocontrol agents against R. solani or Sclerotium rolfsii were observe d in greenhouse experiments.