CONICET | Buscador de Institutos y Recursos Humanos

ABSTRACT: Fusarium sudanense is a novel fungus recently isolated fromasymptomatic samples of wheat grains in Argentina. The fungus causedsymptoms of seedling blight and seed rot on wheat after artificial inoculations.It is known that the production of mycotoxins by pathogens belonging to theFusarium genus is harmful to human and animal health. Moreover, the warmand humid conditions that are favorable for growth and mycotoxinproduction of these species put the Argentinian wheat production area at ahigh risk of mycotoxin contamination with this novel pathogen. The aim ofthis work was to evaluate the antagonistic effect of Trichoderma harzianumagainst F. sudanense under in vitro tests at different environmental conditions.Fungi were screened in dual culture at different water activities (αw) (0.995,0.98, 0.95, and 0.90) and temperatures (25 and 15 °C). The growth rate ofthe fungi, interaction types, and dominance index were evaluated. Also, theinteraction between T. harzianum and F. sudanense was examined by light andcryo-scanning microscopy. T. harzianum suppressed the growth of F. sudanense at 0.995, 0.98, and 0.95 αw at 25 °C and 0.995 and0.98 αw at 15 °C. Macroscopic study revealed different interaction types between F. sudanense and T. harzianum on dual culture.Dominance on contact where the colonies of T. harzianum overgrew the pathogen was the most common interaction typedetermined. The competitive capacity of T. harzianum was diminished by decreasing the temperature and αw. At 0.95 αw and 15 °C,both fungi grew slowly, and interaction type ?A? was assigned. Microscopic analysis from the interaction zone of dual culturesrevealed an attachment of T. harzianum to the F. sudanense hyphae, penetration with or without formation of appressorium-likestructures, coiling, plasmolysis, and a veil formation. According to our results, T. harzianum demonstrated capability to antagonize F.sudanense and could be a promising biocontrol agent.

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