Aislamiento y caracterización de cepas de Trichoderma spp. asociadas a un cultivo de sorgo

Abstract

In this work, fungal species were isolated from three different compartments of a sorghum agroecosystem. Trichoderma spp were isolated: three from leaf tissue, two from root and seven in soil. They were identified by PCR, foliar tissue was identified at T. lixii/H. lixii; in root to T. lixii and T. atroviride and in soil to T. harzianum and T. virens. A strain from each compartment was randomly selected to assess its antagonistic potential against relevant phytopathogens: Fusarium mexicanum (FM), F. pseudocircinatum (FP), Fusarium sp. (FU), Colletotrichum acutatum (CA), C. coccodes (CC), C. gloesporoides de Morelia (CG1), C. gloesporoides de Uruapan (CG2), Phytophthora capsici (PCA), P. cinnamomi de Atécuaro (PC1) and P. cinnamomi de Uruapan (PC2). The level of antagonism was classified according to Bell et al. (1982). Results of the dual culture trials: strains T5HD (leaf tissue) and T4RB (root) class 1 versus FM. T5HD, T4RB and 2T22G (ground) versus CC and CG2, class 1; strains T5HD and 2T22G class 1 against CA and T4RB class 1 against CG1, T5HD, TARB and 2T22G class 1 against PCA, PC1 and PC2. In the Inhibition assays by soluble secondary metabolites (MSS) and by volatile (MSV), they were classified according to Worasatit et al. (1994). The results of MSS inhibition are: 2T22G class 1 against FM, T5HD and 2T22G class 1 against FU. T5HD and 2T22G class 1 against AC, 2T22G class 1 against CC. The three strains evaluated against PCA, PC1 and PC2, class 1. Inhibition by MSV are: class 2 T4RB and 2T22G against FM and FP. T4RB class 2 against tested Colletotrichum species. T4RB class 1 vs. PC1 and PC2. The isolated 2T22G soil strain presented the best antagonistic potential.

En este trabajo se aislaron especies fúngicas de tres compartimentos diferentes de un agroecosistema de sorgo. Se aislaron Trichoderma spp: tres de tejido foliar, dos de raíz y siete en suelo. Se identificaron por PCR, tejido foliar se identificó a T. lixii/H. lixii; en raíz a T. lixii y T. atroviride y en suelo a T. harzianum y T. virens. Se seleccionó al azar, una cepa de cada compartimento para evaluar su potencial antagónico frente a fitopatógenos de relevancia: Fusarium mexicanum (FM), F. pseudocircinatum (FP), Fusarium sp. (FU), Colletotrichum acutatum (CA), C. coccodes (CC), C. gloesporoides de Morelia (CG1), C. gloesporoides de Uruapan (CG2), Phytophthora capsici (PCA), P. cinnamomi de Atécuaro (PC1) y P. cinnamomi de Uruapan (PC2). Se clasificó el nivel de antagonismo según Bell et al. (1982). Resultados de los ensayos de cultivo dual: las cepas T5HD (tejido foliar) y T4RB (raíz) clase 1 frente a FM. T5HD, T4RB y 2T22G (suelo) frente a CC y CG2, clase 1; las cepas T5HD y 2T22G clase 1 frente a CA y T4RB clase 1 frente a CG1, T5HD, TARB Y 2T22G clase 1 frente a PCA, PC1 y PC2. En los ensayos de Inhibición por metabolitos secundarios solubles (MSS) y por volátiles (MSV), se clasificaron según Worasatit et al. (1994). Los resultados de inhibición por MSS son: 2T22G clase 1 frente a FM, T5HD Y 2T22G clase 1 frente a FU. T5HD y 2T22G clase 1 frente a CA, 2T22G clase 1 frente a CC. Las tres cepas evaluadas frente a PCA, PC1 y PC2, clase 1. Inhibición por MSV son: clase 2 T4RB y 2T22G frente a FM y FP. T4RB clase 2 contra las especies de Colletotrichum probadas. T4RB clase 1 frente a PC1 y PC2. La cepa aislada de suelo 2T22G, presentó el mejor potencial antagónico.