Influence of biological parameters and gene transfer technique on transformation of Fusarium oxysporum.

An improved method for PEG-mediated transformation of the fungal pathogen Fusarium oxysporum was developed which led to at least a 10-fold increase in transformation frequency. This improvement was gained through the analysis of biological factors, viz., protoplast origin, plasmid modifications and protoplast/plasmid ratio. Elecroporation, a recently developed method for introducing DNA into many cell types, was successfully applied. It gave similar transformation efficiencies to those obtained with the chemical method, and thus appeared a valuable alternative. Qualitative features such as integration events were also analysed. Molecular analysis of transformants revealed that a single copy of plasmid DNA was preferentially integrated by electroporation. The respective advantages of the two DNA transfer methods are discussed.