Rapid Deletion Production in Fungi via Agrobacterium Mediated Transformation of OSCAR Deletion Constructs

Precise deletion of gene(s) of interest, while leaving the rest of the genome unchanged, provides the ideal product to determine that particular gene's function in the living organism. In this protocol the OSCAR method of precise and rapid deletion plasmid construction is described. OSCAR relies on the cloning system in which a single recombinase reaction is carried out containing the purified PCR-amplified 5' and 3' flanks of the gene of interest and two plasmids, pA-Hyg OSCAR (the marker vector) and pOSCAR (the assembly vector). Confirmation of the correctly assembled deletion vector is carried out by restriction digestion mapping followed by sequencing. Agrobacterium tumefaciens is then used to mediate introduction of the deletion construct into fungal spores (referred to as ATMT). Finally, a PCR assay is described to determine if the deletion construct integrated by homologous or non-homologous recombination, indicating gene deletion or ectopic integration, respectively. This approach has been successfully used for deletion of numerous genes in Verticillium dahliae and in Fusarium verticillioides among other species.