Aislamiento y caracterización de antagonistas fungosos cultivables, nativos de suelos agrícolas del cantón Santa Cruz parroquia Bellavista de la provincia de Galápagos.

Abstract

The objective of this research work was to isolate and characterize culturally, morphologically, and molecularly cultivable antagonistic fungi native to agricultural soils of the Santa Cruz canton, Bellavista parish, Galapagos province. The soil samples corresponded to 8 crops of the Santa Cruz canton (Kale, melon, coffee var. Catimor and var. Típica, tomato, yellow corn, undisturbed forest, and bell pepper). The stock solution was prepared where 27.77 g of soil diluted in 250 mL of water was taken, and three replicates per sample were made, in 4 culture media: potato dextrose agar (PDA), potato dextrose agar amended (PDAE), Rose Bengal (RB) and Selective medium for Trichoderma (TSM), the sowings were conserved at 25°C and were observed characteristics of Trichoderma spp., such as phialides, chlamydospores, and conidia. It was necessary to perform molecular characterization to determine the genus and species. Genomic DNA extraction was performed with the help of the Promega Wizard® Kit, and the DNA polymerase chain amplification (PCR) technique in the Rpb2 program was used for identification. As a result of the eight crops sampled, the one that presented the highest number of isolates was the coffee var. catimor crop with six isolates, followed by the Kale crops with 4, melon 4, and coffee var. Típica 1, tomato 1, yellow corn 4, undisturbed forest 1, and bell pepper 0 isolates. The Trichoderma species obtained were harzianum, lentiforme, breve, andinense, longibrachiatum, and reesei. It was concluded with the obtaining of 21 strains, two clades, and six species in the phylogenetic analysis. In addition, the most appropriate technique for the isolation was the sowing by the dilution method and extension in the plate in the RB culture medium. It is recommended to carry out antagonism tests with the 21 strains of Trichoderma.