Involvement of ThSNF1 in the development and virulence of biocontrol agent Trichoderma harzianum

Trichoderma harzianum, a biocontrol agent for various plant pathogens, is known to degrade fungal cell walls; this mycoparasitism is believed to require secretion of cell-wall-degrading enzymes against host pathogens. In this study, we identified a homologue of yeast SNF1 (sucrose nonfermenting 1) encoding protein kinase in T. harzianum (ThSNF1) by draft genome sequencing of strain T36. Targeted gene disruption of ThSNF1 was performed using the PEG method with fusion PCR products. Growth of mutant ΔThSNF1 was markedly less than for the wild-type strain on minimal medium with chitin as a carbon source. The mutant exhibited reduced expression of the genes encoding chitinase and polygalacturonase and markedly reduced spore production. Mycoparasitism against plant pathogens such as Fusarium oxysporum f. sp. cubense (Panama disease) and Fusarium graminearum (Fusarium head blight) was clearly impaired in the mutant. The results suggest that ThSNF1 is critical for asexual development, utilization of certain carbon sources and virulence on fungi, and is therefore important for the biocontrol ability of T. harzianum.