Production of Inter‐ and Intra‐strain Hybrids of Trichoderma spp. by Protoplast Fusion and Evaluation of Their Biocontrol Activity Against Soil‐borne and Foliar Pathogens

Abstract

AbstractProtoplast fusion techniques were used for the production of new antagonistic strains of Trichoderma spp. Two British and two Italian strains of Trichoderma with different biocontrol potential against Botrytis cinerea, Sclerotinia sclerotiorum and Pythium ultimum, were treated with u.v. radiation and mutants resistant to hygromycin B or propiconzole were selected. Protoplasts were obtained from these mutants after digestion of young hyphae with Novozym 234 and used in inter‐ and intra‐strain protoplast fusion experiments. Hybrids were obtained in 13 crosses isolated on fungicide‐amended media by the inheritance of resistance markers from both parental strains. Selected, fast‐growing, stable mutants were tested in biocontrol trials against P. ultimum on lettuce seedlings and B. cinera on grape bunches in comparison with their parental strains. Intra‐strain hybrids derived from cross XIII were tested in vitro for their mycoparasitic ability on sclerotia of S. sclerotiorum. A high degree of variability in the biocontrol and the mycoparasitic ability of the fusants was observed but no significant increase in the activity was accomplished after fusion, the hybrids being generally less activewas accomplished after fusion, the hybrids being generally less active than their parental strains.