Fusarium oxysporum f.sp vasinfectum, (FOV) the causal organism of Fusarium wilt, is a significant threat to the Australian cotton industry. It is therefore essential that various strategies for the development of solutions to this problem are explored. It is hoped that an improved understanding of the genetic factors responsible for the pathogenicity of Fov will uncover novel approaches for disease control. We are implementing a transformation protocol for Fov and developing a project aimed at identifying pathogenicity genes using gene disruption and tagging techniques. We are also generating Fov transformants expressing marker genes to facilitate studies of the interactions of the host and the pathogen.