Submitted to: Plant Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/3/2010
Publication Date: 4/1/2010
Citation: Di, R., Blechl, A.E., Dill-Macky, R., Tortora, A., Tumer, N.E. 2010. Expression of a truncated form of yeast ribosomal protein L3 in transgenic wheat improves resistance to Fusarium head blight. Plant Science. 178: 374-380. Interpretive Summary: Fusarium head blight (FHB) is a plant disease that results in major economic losses in wheat and barley production worldwide. The fungus that causes FHB makes mycotoxins during infection that can contaminate food and thus become a major health concern for humans and animals. The toxins act by interacting with ribosomal protein L3 and inhibiting protein synthesis in animal and plant cells. The fungus benefits from this toxicity since the dying plant cells cannot mount defense responses. In this study, we produced transgenic wheat plants that accumulate a short form of a yeast L3 protein (L3') in the green tissues of young flowers before anthesis. Of five transgenic wheat lines characterized in detail, the two expressing the highest levels of L3' showed reductions in FHB disease severity and kernel toxin levels when compared to non-transformed plants in greenhouse infection tests. In a field test in a year with very high disease pressure, a transgenic wheat line with the highest L3' expression had significant reductions in visually scabby kernels and kernel toxin levels. These results demonstrate that a modified form of the ribosomal protein that is the target of mycotoxin inhibition can partially protect wheat plants from FHB.
Technical Abstract: Fusarium head blight (FHB) is a disease that causes major economic losses in wheat and barley production worldwide. Contamination of food with the trichothecene mycotoxin deoxynivalenol (DON) produced by Fusarium is a major health concern for humans and animals because trichothecenes are potent cytotoxins of eukaryotic cells. Trichothecene mycotoxins inhibit translation by targeting ribosomal protein L3 at the peptidyltransferase center. Expression of an N-terminal fragment of yeast L3 (L3') in transgenic tobacco plants eliminated the toxicity of DON and pokeweed antiviral protein (PAP), a ribosome inactivating protein that also targets L3. Here, we produced transgenic wheat plants that express the yeast L3 (L3') and evaluated their susceptibility to F. graminearum infection and their ability to accumulate DON. Following F. graminearum infection in greenhouse tests, two transgenic wheat lines expressing the highest levels of L3' showed reductions in disease severity and kernel DON levels, compared to non-transformed plants. In a field test, a transgenic wheat line with the highest L3' expression controlled by the maize Ubi1 promoter had significant reductions in visually scabby kernels and kernel DON levels. These results demonstrate that expression of a modified form of the ribosomal protein that is the target of DON inhibition can improve FHB resistance in wheat.