DUGi

Postinfection activity of synthetic antimicrobial peptides against Stemphylium vesicarium in pear

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Brown spot of pear is a fungal disease of economic importance caused by Stemphylium vesicarium that affects the pear crops in Europe. Due to the characteristics of this disease and the moderate efficacy of available fungicides, the effectiveness of control measures is very limited; however, synthetic antimicrobial peptides (AMPs) may be a complement to these fungicides. In the present study, 12 AMPs of the CECMEL11 library were screened for fungicidal activity against S. vesicarium. In vitro experiments showed that eight AMPs significantly reduced the germination of conidia. The most effective peptides, BP15, BP22, and BP25, reduced fungal growth and sporulation at concentrations below 50 μM. Leaf assays showed that preventive application of BP15 and BP22 did not reduce infection; however, when the peptides were applied curatively, infection was significantly reduced. The use of a BP15 fluorescein 5-isothiocyanate conjugate revealed that the peptide binds to hyphae and germ tubes and produces malformations that irreversibly stop their development

This research was supported, in part, by grants from the Ministerio de Educacion y Ciencia (AGL2009-09829/AGR) of Spain and the Comissio Interdepartamental de Recerca i Tecnologia of the Generalitat de Catalunya (2009SGR00812). M. Puig was the recipient of a predoctoral fellowship from Universitat de Girona (BR10-17)

American Phytopathological Society