Chemistry and physiology of deoxynivalenol in pathogenesis

The focus of this presentation is on the role of deoxynivalenol in pathogenesis. Single-kernel analysis is the model system developed for the study of this disease. In natural infection, DON is found in the spikelets other than those showing symptoms and is most likely due to spread of the fungus. In wheat and barley heads inoculated with DON, no translocation of DON out of the spikelets was noted after 12, 24, and 48 hours. Macroconidia of F. graminearum isolates did not contain DON when grown on mung bean agar although these same isolates when inoculated into spikelets of wheat produced the toxin. In inoculation of single kernels of wheat, DON as well as 15-acetyldeoxynivalenol are produced as soon as 48 hours after inoculation. Trichodiene mutants that do not produce DON did not do so when inoculated into single spikelets on wheat heads although they did show mild symptoms of infection. The wild type (DON producer) caused mores severe symptoms of infection than the mutant.