This project was designed to assess the potential of a plant derived antifungal gene (NaD1) for control of cotton pathogens. The NaD1 gene codes for a small protein called a plant defensin. Previous in vitro assays have shown that purified NaD1 can inhibit the germination and hyphal growth of the fungus Fusarium oxysporum f.sp vasinfectum (Fov) which causes Fusarium wilt in cotton.

The major aim of the project was to assess the efficacy of the defensin protein, NaD1, against three cotton pathogens: Fusarium oxysporum, Verticillium dahliae which causes Verticillium wilt and Thielaviopsis basicola which causes black root rot.

Four transgenic cotton lines transformed with the NaD1 gene were supplied by Hexima Ltd for this project. The lines expressed the NaD1 protein at high levels in the leaves and roots of seedlings. At least three of the lines had a single copy of the NaD1 gene. The lines were assessed in glasshouse bioassays using either a seedling dip infection method or an infected soil based method. In limited trials, one transgenic line showed enhanced resistance to Fov and T. basicola. Further bioassays with this line to confirm the project findings is planned. In the long term it is hoped that this gene can be transferred into elite varieties to enhance the resistance of Fov in the field.