Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/27/1996
Publication Date: N/A
Technical Abstract: The role of host response genes in disease resistance is often uncertain or unknown. Some have been shown to enhance resistance when introduced by transformation into susceptible plants. However, the generation of transgenic cereals to test the effectiveness of disease response genes is a lengthy and costly process. For this reason, we have developed a rapid transient expression assay using barley coleoptiles for evaluating the ability of individual genes to confer disease resistance in cereals. Particle bombardment is used to co-transform epidermal cells with a host response gene in combination with genes that regulate anthocyanin production. Transformed cells turn red within 1-2 days and are subsequently challenged with spores of the powdery mildew fungus, Erysiphe graminis f.sp. hordei. The effects of the transiently expressed host response gene on fungal development can be directly observed on the living coleoptile tissues using microscopy. The accumulation of anthocyanins have no effect on the rates of infection or the development of the fungus. In our initial experiments, host response genes for chitinase, Beta-1, 3-glucanase, and a thaumatin-like protein each significantly reduced rates of infection by 1/2 to 2/3 in transiently expressing epidermal cells. This new procedure provides a useful tool for prescreening the ability of host response genes to confer disease resistance, singly or in combination, prior to the generation of stable transformants. In addition, this assay is potentially useful for investigating the expression of other genes postulated to have a role in host-parasite interactions.