CHEMISTRY AND PHYSIOLOGY OF DEOXYNIVALENOL IN PATHOGENESIS

The focus of this presentation is on the role of deoxynivalenol in pat hogenesis. Single-kernel analysis is the model system developed for th e study of this disease. In natural infection, DON is found in the spi kelets other than those showing symptoms and is most likely due to spr ead of the fungus. In wheat and barley heads inoculated with DON, no t ranslocation of DON out of the spikelets was noted after 12, 24, and 4 8 hours. Macroconidia off. graminearum isolates did not contain DON wh en grown on mung bean agar although these same isolates when inoculate d 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 no t produce DON did not do so when inoculated into single spikelets on w heat heads although they did show mild symptoms of infection. The wild type (DON producer) caused mores severe symptoms of infection than th e mutant.