To understand the mechanisms involved in the activity of antagonists it is crucial, for the optimisation of their performances, to establish screening criteria in the search for new isolates and for the possible combined utilisation of biological control agents acting through complementary modes of action. An isolate of the yeast like fungus Aureobasidium pullulans (LS-30) showed a significant antagonistic activity against some of the most important postharvest pathogens on apples and table grapes, both in small scale experiments and under semi-commercial conditions. Studies on the mechanisms involved in the activity of this antagonist were performed. We examined: i) the possible occurrence of a direct physical interaction between the antagonist cells and hyphae of Botrytis cinerea and Penicillium expansum, a phenomenon often associated with mycoparasitism; ii) the role of competition for nutrients; iii) the in vitro (i.e. in the culture filtrates) and in vivo (i.e. in apple wounds, one of the conditions in which the antagonist was assayed) production of exocellular chitinase and b1,3-glucanase activities, fungal cell wall depolymerases involved in the antagonism of mycoparasites such as Trichoderma spp. Further, we performed plate assays to test the possible presence of antibiosis in the activity of LS-30 against B. cinerea and P. expansum, and TLC assays to assess the possible antibiotic activity against Gram positive and Gram negative bacteria of ethyl acetate extracts obtained from the antagonist culture filtrate.

Mechanisms of action involved in the antagonism of Aureobasidium pullulans against postharvest pathogens

CASTORIA, Raffaello;DE CURTIS, Filippo;LIMA, Giuseppe;
1998-01-01

Abstract

To understand the mechanisms involved in the activity of antagonists it is crucial, for the optimisation of their performances, to establish screening criteria in the search for new isolates and for the possible combined utilisation of biological control agents acting through complementary modes of action. An isolate of the yeast like fungus Aureobasidium pullulans (LS-30) showed a significant antagonistic activity against some of the most important postharvest pathogens on apples and table grapes, both in small scale experiments and under semi-commercial conditions. Studies on the mechanisms involved in the activity of this antagonist were performed. We examined: i) the possible occurrence of a direct physical interaction between the antagonist cells and hyphae of Botrytis cinerea and Penicillium expansum, a phenomenon often associated with mycoparasitism; ii) the role of competition for nutrients; iii) the in vitro (i.e. in the culture filtrates) and in vivo (i.e. in apple wounds, one of the conditions in which the antagonist was assayed) production of exocellular chitinase and b1,3-glucanase activities, fungal cell wall depolymerases involved in the antagonism of mycoparasites such as Trichoderma spp. Further, we performed plate assays to test the possible presence of antibiosis in the activity of LS-30 against B. cinerea and P. expansum, and TLC assays to assess the possible antibiotic activity against Gram positive and Gram negative bacteria of ethyl acetate extracts obtained from the antagonist culture filtrate.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11695/8575
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