CONICET | Buscador de Institutos y Recursos Humanos

Alfalfa (Medicago sativa L.) is an important legume forage grown worldwide with around 35 million hectares cultivated over more than 80 countries. Due to the expansion of extensive crops, alfalfa production has shifted to marginal areas with poorly drained soils, which directly affects the productivity and persistence of this crop. Biological control provides an alternative to the use of synthetic pesticides with the advantages of greater public acceptance and lower environmental impact. The use of rhizospheric microorganisms as biological control agents seeks to restore the beneficial balance of natural ecosystems.Trichoderma is a genus of filamentous free-living fungi with the ability to antagonize plant-pathogenic fungi and to stimulate plant growth and defense responses. Trichoderma species are highly interactive in root, soil and foliar environments and have been used successfully in field trials to control many crop pathogens like Sclerotium rolfsii and Rhizoctonia solani. In this study, the influence of the inoculation of six native Trichoderma strains on the growth of alfalfa and Arabidopsis thaliana and their action as biological protectors against pathogenic fungi were analysed. Competition assays revealed three Trichoderma spp. strains as antifungal agents against Macrophomina phaseolina and Fusarium spp. We also examined the root structure of the plants using the image analysis tool ARIA (Automatic Root Image Analysis), founding a significant increase in the development of secondary roots, both in arabidopsis and alfalfa, when plants were faced with the fungi in Petri dishes. The number of root hairs also enlarge in plants under the presence of Trichoderma, which could indicate a greater capacity for uptake nutrients and water. This result could be translated into a higher biomass production of these plants, a hypothesis that is under study.