Fusarium head blight (FHB) is a devastating disease of wheat throughout the world. FHB is primarily caused by the fungal pathogen Fusarium graminearum. In wheat, benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH) induces the wheat chemically-induced (WCI) genes and provides resistance to several pathogens. The objectives of this study were two-fold: (1) to investigate the effects of BTH application and F. graminearum infection on selected defense response genes in wheat spikes; and (2) to study the potential of BTH for inducing FHB resistance in wheat. Wheat spikes were treated with BTH prior to anthesis and transcript accumulation and resistance to FHB were measured. BTH-treated wheat spikes were examined for expression of six defense response genes (PR-1, PR-2, PR-3, PR-4, PR-5 and peroxidase) and the five WCI genes that are induced by BTH in wheat leaves. All five WCI genes were induced by BTH in spikes; however none of the six defense response genes were induced. Conversely, the defense response genes were induced by F. graminearum infection, whereas the WCI genes were not. These data indicate that the pathway for induction of the defense response genes by F. graminearum infection is distinct from the BTH-induced pathway. In the disease evaluations of BTH-treated plants, we found that BTH did not provide significant Type I or Type II resistance to wheat spikes spray- or point-inoculated with F. graminearum, respectively. These data indicate that BTH application and the induction of WCI gene expression does not provide resistance to FHB.
Bibliographical noteFunding Information:
The authors thank W. R. Bushnell and D. A. Somers for critical review of the manuscript, R. Dudler (University of Zurich) for the wheat peroxidase clone, H. Thordal Christensen (KVL, Denmark) for the barley PR-3 and PR-5, L. Friedrich (NOVARTIS) for the wheat PR 1-2 clone and K. Beasley (NOVARTIS) for the WCI 1-5 clones. This work was funded through a grant from the Minnesota State Legislative Scab Initiative to GJM.
- Benzo(1,2,3)thiodiazole-7-carbothioic acid S-methyl ester (BTH)
- Fusarium graminearum
- Fusarium head blight
- Triticum aestivum