Pedigree and xylanolytic properties of T. reesei strains used in this study. (A) Schematic drawing of the pedigree of strains of which investigated ones are shown in boxes. Next to arrows the method of strain generation is indicated: UV-mutagenesis (UV), nitrosoguanidine (NTG), spontaneous mutation (SM). White arrows indicate strain generation before this study, grey arrows indicate strain generation during this study, black arrows indicate strains generated by targeted gene replacement during this study. Xylanolytic properties of strains generated during this study are represented by growth on plates containing 0.2% (w/v) azo-xylan as carbon source at 30°C for 24 h (B) and for 72 h followed by a 2 h incubation at 50°C (C).