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.