A Saprotrophic Fungal Isolate From Northern Sinaloa, Mexico, with Homology to Members of the Chaetomiaceae Behaves as an Antagonist of Phytopathogenic Fungi in vitro

Abstract

An ascomycete was isolated from spore preparations of arbuscular mycorrhizal fungi from soil samples collected in northern Sinaloa, Mexico. This fungal isolate named CIIDIR-1, is ubiquitous in soils of this agricultural region. Only the asexual phase of CIIDIR-1 can be cultured in vitro in different culture media. DNA extracted from mycelium was used to amplify and sequence a 28S rDNA hypervariable region, which allowed its identification as related to members of the Chaetomiaceae family (Aporothielavia leptoderma and members of the genus Chaetomium). CIIDIR-1 showed a saprophytic behavior in the presence of plant roots grown in vitro. Bioassays showed that the isolate acts as an antagonist against phytopathogenic fungi. When mycelium from the isolate was placed in contact with Rhizoctonia solani and Fusarium oxysporum f. sp. lycopersici, it proliferated, surrounded them and inhibited their growth. The presence of CIIDIR-1 in all soil samples evaluated suggests an important role in the rhizosphere; also, the understanding of its interactions with plants and other rhizospheric organisms might be important for future ecological and agricultural studies. Additional keywords: Aporothielavia leptoderma, 28S rDNA hypervariable region, Rhizoctonia solani, Fusarium oxysporum f. sp. lycopersici, antagonism.