In vitro antifungal activity of brassinin, camalexin and two isothiocyanates against the crucifer pathogens Alternaria brassicicola and Alternaria brassicae
Résumé
In vitro assays investigated the responses of Alternaria brassicicola and A. brassicae isolates towards two crucifer phytoalexins and two isothiocyanates (ITC) by evaluating their potential toxic effects on different fungal growth parameters. Although variable responses towards each compound was observed within the species A. brassicicola, the results obtained confirmed the antifungal effects of camalexin, brassinin, allyl- (AlITC) and benzyl- (BzITC) isothiocyanates, at different developmental stages of both Alternaria species. Irrespective of the tested isolate, the phytoalexin camalexin exhibited the greater inhibitory effect with mean EC50 values ranging from 34 mu M (germ-tube elongation) to 183 mu M (mycelial growth). Germ-tube elongation was more sensitive compared to conidial germination and mycelial growth, with mean EC50 values of the former of 81 mu M, 520 mu M and 870 mu M for brassinin, BzITC and AlITC, respectively
