Effects of protoplast fusion on the antifungal activity of Trichoderma strains and their molecular characterisation

摘要

The main purposes of this study were to examine the effects of protoplast fusion on chitinase production, antifungal activity and major antifungal compounds in parental strains and fusants and to investigate them using the internal transcribed spacer-restriction fragment length polymorphism (ITS-RFLP) method. The chitinase levels of eight fusants named Fu1-Fu8, formed by protoplast fusion between endophytic Trichoderma harzianum strains, were compared. Antifungal activities of the eight fusants weretested against Rhizoctonia solani, Sderotinia sclerotiorum and Aspergillus flavus. Pathogens were significantly controlled by the fusant Fu3. Isolation and purification of the compounds from the fusant Fu3 and parental strains were done based on the preparative thin layer chromatography method. After an antifungal activity assessment of isolated fractions, Fr5 and Fr2Fr2 fractions from fusant Fu3 and parental strains were injected into liquid chromatography-mass spectrometry (LC-MS). Harzianopyridone and chryso-phanic acid compounds were identified in the Fr2Fr2 and Fr5 fractions which showed the greatest effect on 5. sclerotiorum, R. solani and A. flavus, respectively.