BIOCONTROL DE Rhizopus stolonifer EN FRUTOS DE ZARZAMORA (Rubus fruticosus) EMPLEANDO MICROBIOTA NATIVA, ASOCIADA A LA PLANTA

Abstract

The use of synthetic fungicides render severe side effects affecting the biosphere, environment, and human health, they even induce resistance on plant pathogens. The usage of antagonist microorganisms against postharvest pathogens offers a viable option with hopeful results. In this study the main purpose is to obtain the native microorganisms associated to blackberry fruit crop in order to determine the potential antagonist effects over the soft rot caused by Rhizopus stolonifer. This fungus disease is considered a devastating threat fungus for fruits and vegetables worldwide. Native microbiota was isolated from plant „Brazos‟ variety samples of a commercial blackberry fruit exporter zone located in Atapan Michoacán, Mexico. The pathogenicity of 5 isolates from Rhizopus genus was determined. The antagonistic potential in vitro of 113 microorganisms was evaluated on PDA medium, such as antifungal index of the most effective antagonists. Confrontations against R. stolonifer in situ were also evaluated, determining severity grade, inhibition percentage and incidence of disease percentage. Four bacterial isolates showed efficient antagonistic activity against two R. stolonifer isolates. Three of them belong to Bacillus genus and the last one to Leifsonia genus, which had no antagonistic properties on previous reports. The main antifungal index had a mean up to 42.78% in vitro, while the disease incidences were signifincantly reduced to a 15% (Tukey p˂0.005). Also a detailed description of infection process for blackberry fruit in particular was obtained. A deeper understanding on the interactions among fruit, antagonist and postharvest‟s pathogens is needed in order to elucidate the biological process previous to mechanisms of action involved in biological control. This information could help to develop technological strategies applied to integrated postharvest disease management and consequently achive productive and sustainable agricultural systems.