The viral gene for the killer protein 4 (KP4) has been explored for its 
antifungal effect in genetically modified wheat to defeat specifically the 
seed-transmitted smut and bunt diseases. In vitro both important 
seed-transmitted diseases of wheat, loose smut (Ustilago tritici) and stinking 
smut (Tilletia caries), are susceptible to KP4, whereas all other organisms 
tested so far proved to be not susceptible to KP4. For studies in planta we used 
stinking smut as a model fungus. In greenhouse experiments, two KP4-transgenic 
wheat lines showed up to 30% lower symptom development as compared to the 
nontransgenic control. As the last step in the proof of concept, field-testing 
has shown for the first time increased fungal resistance of a transgene in 
wheat. Due to its specificity against smuts and bunts, KP4 presents a very low 
risk to humans and the environment. Field-testing in Switzerland is regulated by 
a strong law, which for research is acceptable if legally and scientifically 
correctly applied.