Sequential distribution of the mycotoxin deoxynivalenol in wheat spikes after inoculation with Fusarium graminearum

One central spikelet of spring wheat (Triticum aestivum) cv. Roblin spikes was inoculated with macroconidia of Fusarium graminearum and the entire spi kes were harvested at 2- to 4-day intervals from 2 to 25 days after inocula tion. The spikes were dissected and the amount of deoxynivalenol (DON) in e ach spikelet and in each internode of the rachis was measured by enzyme-lin ked immunosorbent assay (ELISA) with monoclonal antibodies. High concentrat ions of DON were first detected in the inoculated spikelets, 4 days after i noculation. DON concentrations in the spikelets below the inoculation point eventually reached 500-600 ppm while the corresponding internodes of the r achis contained 1000-1200 ppm. Much lower amounts of DON were found in spik elets and rachis above the inoculation point.