Morphological and molecular characterization of a new autochthonous Trichoderma sp. isolate and its biocontrol efficacy against Alternaria sp.

The development of agriculture requires the use of microorganisms in the management of phytopathogens as a way to compensate for the use of chemical pesticides, in order to produce healthy crops. The objective of this study was to characterize a new isolate of Trichoderma sp. based on morphological and molecular features, and its potential ability to control the pathogen Alternaria sp. The antagonistic isolate was isolated from soil samples of potato fields in Guasave Sinaloa, Mexico, whereas the pathogen was collected from infected apple leaves in the orchard “La Escondida” in Guerrero County, Chihuahua, Mexico. For morphological characterization both fungi were grown on solid PDA medium. DNA of Trichoderma sp. was isolated using the CTAB method and PCR analyses were done using ITS1, ITS4 primers resulting in amplified products of 600 bp. These were sequenced, submitted to Genbank (acc. no. MN950427) and used for further phylogenetic analysis through Bayesian inference approach. Five clades were identified and the polytome topography recovered from clade 4 indicates a high genetic similarity with T. asperellum. A BLAST examination of the resulting sequence in GenBank showed 98.11% similarity with T. asperellum. This result together with the morphological and the phylogenetic analyses indicates that the isolate belongs to Trichoderma asperellum Samuels, Lieckfeldt & Nirenberg. Biocontrol tests of this isolate showed inhibition of Alternaria sp. between 50% and 93%. These results are essential for biodiversity research and give some new possibilities for pest management.