Submitted to: National Fusarium Head Blight Forum Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 10/8/1999
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: The early events in the infection process of wheat spikes by Fusarium graminearum Schw. were examined. Glumes from spray-inoculated spikes (1 million conidia/ml) of Sumai (resistant) and Wheaton (susceptible) were sampled at 6, 12, 24, 36, 48, and 76 hours after inoculation and the abaxial surface examined using both scanning electron microscopy and light microscopy of calcofluor stained sections. Conidia germination occurred between 6-12 hours. Between 24-48 hours some subcuticular hyphal development was evident and other hyphae were found to penetrate stomata. By 48-76 hours after inoculation, hyphae were abundant on the glume surface, especially in areas occupied by stomatal rows and conidiophores were present. Also, hyphae were found within both epidermal and parenchyma cells. No major differences in the timing of these events were found between the two cultivars. Additionally, RNA was extracted from whole wheat spikes collected from the two cultivars at the same timepoints. RNA blot analysis was used to determine the expression pattern of several defense genes in the spikes during Fusarium infection. Preliminary results indicate that several defense genes were strongly induced by 48 hours after inoculation, including genes for chitinase, glucanase, peroxidase and thaumatin-like protein.