Abstract

The increase in endochitinases and -1,3-glucanases in the mutant Th650-NG7 of the Trichoderma harzianum Th650, improves the biocontrol activity on Rhizoctonia solani infecting tomato Luz M. Pérez1 , Rubén Polanco1 , Juan C. Ríos1 , Jaime Montealegre2 , Luis Valderrama2 , Rodrigo Herrera2 , Ximena Besoaín3 1 Departamento de Ciencias Biológicas, Facultad Ciencias de la Salud, Universidad Andrés Bello. República 217, 3° Piso, Santiago, Chile; 2 Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas, Universidad de Chile, Avda. Santa Rosa 11315 Santiago, Chile; 3 Facultad de Agronomía, P. Universidad Católica de Valparaíso, Quillota, Chile, e-mail: [email protected] Abstract: The mutant Th650-NG7 obtained after treatment of a wild isolate of T. harzianum (Th650) with N-methyl-N-nitro-N-nitrosoguanidine (NG), increased two and four fold total β-1,3-glucanase and endochitinase activities, respectively, and improved the biocontrol activity on R. solani. Glasshouse assays showed that Th650-NG7 prevented the 60 and 20% mortality observed in tomato plants of cvs. 92.95 and Gondola respectively, as a consequence of their inoculation with high pressure of R. solani and the parental strain (Th650). Results show a correlation between biocontrol ability of Th650-NG7 and secretion of R. solani cell wall hydrolyzing enzymes.