Fungal endophytes in species of Paspalum and Bromus, occurrence and potential ability for biological control.

GARCÍA, A.; GIL- CARDEZA, L.B.; GÓMEZ, E.; FELITTI, S.A.

Buenos Aires, Argentina.

Simposio; 5th International Symposium of Forage Breeding.; 2015

Facultad de Agronomía, Universidad de Buenos Aires

Endophytic fungi are a very diverse polyphyletic group of microorganisms that can thrive asymptomatically in aboveground as well as belowground plant tissues. Grasses of the family Poaceae and fungi of the family Clavicipitaceae have a long history of symbiosis and these interactions have been thoroughly studied. In the more mutualistic symbiota, the endophytes gain shelter, nutrition, and dissemination via host seeds, and can contribute an array of host fitness enhancements. Particularly in pastures, where the establishment of forage species is affected by multiple biotic and abiotic factors, the potential benefit of this partnership opens an attractive perspective for biotechnological application, such as the biological control. Taking advantage of naturally occurring enemies to control pest is an ecologically relevant alternative to chemical-based pest control.The aims of this work were to study the occurrence of fungal endophytes in Paspalum dilatatum, P. notatum, Bromus biebersteinii and B. catharticus, representative forage species from the Pampa Region of Argentina and to evaluate their potential as antagonistic agents against fungal pathogens. Seventy-two fungal strains were isolated, the vast majority of which (60 isolates) were ascomycete fungi. Most of the isolates belonged to the genera Acremonium, Alternaria, Aspergillus, Curvularia, Fusarium, Penicillium and Stemphyllium. The endophytes of the genus Acremonium showed antagonistic activity against different pathogenic species tested in dual cultures. The results suggest that the interactions and mechanisms of antagonism of the same endophyte strain vary according to the pathogenic strains to which they are faced to. Two possible mechanisms for the antagonistic action were evidenced, mycoparasitism and production of metabolites or fungal toxins during competition. The genus Acremonium detected in this study would contribute to the list of endophytes from the order Hypocreales in temperate areas, since we have not found previous reports related to the isolation of Acremonium species associated with these forage species. According to these results, strains of Acremonium could be good candidates for biological control of latent pathogens in pastures, such as Alternaria alternata, Alternaria sp., Curvularia clavata and C. pallescens. Future studies focused on the analysis of the secondary metabolites produced by the antagonists in the culture medium, as well as assays in planta, will contribute to elucidate the antagonistic effect of the strains tested.