CONICET | Buscador de Institutos y Recursos Humanos

Trichoderma spp. are among the most frequently isolated soil fungi. They are opportunistic, avirulent, plant symbionts, and function as parasites and antagonists of many other phytopathogen fungi, exerting beneficial effects on plant growth and development. The use of the fungal genus Trichoderma to control fungal plant diseases is a promising alternative to the use of chemical compounds. For this reason, integrated characterization of the isolates including combination of molecular, physiological and biochemical attributes could help to select isolates with potential application on biological control of fungal pests and further formulation. Sixteen monoconidial isolates of Trichoderma harzianum Rifai were isolated obtained from the South-East region of Buenos Aires Province (Argentina) and characterized on the basis of thirty morphological, physiological and biochemical features. The results were subjected to numerical analysis that revealed three distinct groups. The antagonistic activity of the T. harzianum isolates was tested against two isolates of six different fungal plant pathogens: Alternaria sp., Bipolaris sorokiniana, Cladosporium sp., Dreschlera-tritici-repentis, Fusarium graminearum, F. solani, and Pyricularia oryzae. Marked inhibition of the growth of the fungal pathogens studied occurred in the presence of most T. harzianum isolates assayed. Two different patterns of inhibition of fungal plant pathogens colonies were observed. The molecular characterization of the native isolates was done using two UP-PCR primers. Four different haplotypes could be identified among the sixteen isolates analysed. One haplotype grouped isolates that showed mycelial growth at high temperatures, spore resistance to heating, extracelullar hydrolytic activity and fungal inhibition against all plant pathogens evaluated. This study is a first approach to characterize a group of T. hazianum isolates form a limited area in Argentina. Although other studies could be done for complementing this characterization, the integration of the methodologies used here could contribute to select most efficcient biological control strains for further formulation.