Secondary metabolite production of an antagonistic Acremonium sp., isolated from asymptomatic grapevine leaves infected by Plasmopara viticola

• Published in: Journal of plant pathology 2003-12, Vol.85 (4), p.285-285
• Main Authors: Assante, G, Nasini, G, Burruano, S, Cannizzaro, G, Torta, L
• Format: Article
• Language: English
• Subjects: Plasmopara viticola
• ISSN: 1125-4653

A strain of Acremonium sp., named A20, was recently isolated from Plasmopara viticola sporangiophores developed on artificially inoculated grapevine leaves. This strain was particularly effective in causing an early degeneration of sporangiophore branches, by growing and rapidly bridling the structures of the plant pathogen until their collapse on the underlying plant tissues. Cultural filtrates of A20 (CFs), grown on potato broth, decreased the germinability of P. viticola sporangia to 13-35% in comparison with the control (82%) after 1 h of contact. CFs were also able to inhibit to some extent the growth of others pathogens, when added at different concentrations to the growth medium. As a part of a program aimed at understanding the nature of the interaction, the results are reported of purification and isolation of secondary metabolites produced by A20 grown on different cultural media. A series of structurally related metabolites was produced, whose amount and chemical structure were affected by the composition of the medium. The main metabolite is a new C sub(12)Hd18 O sub(4), named acremonine A, which was tentatively characterized by means of super(1)H and super(13)C NMR studies. Growth inhibition of several plant pathogenic fungi ranged from 30% to more than 80%, in relation to concentrations of the crude extracts (CEs) or purified metabolite and sensitivity of the tested species. In dual cultures, a typical antagonistic drop growth or a respect zone of no growth were often observed. Germinability of P. viticola sporangia was negatively affected by CEs as already shown with CFs.