Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/14/2005
Publication Date: 11/28/2005
Citation: Skadsen, R.W., Federico, M.L., Abebe, T., Patel, M. 2005. Fighting fusarium head blight of barley with members of the thionin gene family. Proceedings of the 39th Annual Conference on Gene Families and Isozymes. p. 26.
Technical Abstract: The fungal pathogen Fusarium graminearum destroys barley and wheat crops in the U.S. and elsewhere by causing scab (Fusarium head blight) and depositing mycotoxins such as DON. These make the harvest unsuitable for food, feed or malting. There are no known barleys with biochemical resistance to Fusarium. Genetic transformation with antifungal genes could provide resistance, but it is necessary to 1) utilize a gene encoding a protein toxic to Fusarium, 2) determine the route of infection, and 3) develop tissue-specific gene promoters to express the gene in the path of infection. We have found that Fusarium rapidly colonizes the ovary epithelial hairs that protrude from the tip of the seed and colonizes the lemma (outer seed hull) much later. The ovary epithelial hairs are continuous with the epicarp, which supports rapid infection of the developing seed. No penetration of the endosperm occurs for weeks. Thus, promoters to target transgenes to the epicarp and the lemma are needed. We have shown that barley thionin proteins from the seed and the lemma are highly toxic to Fusarium. We are presently attempting to transform barley with a vacuolar thionin gene. Gene encoding a lectin-like protein, Lem2, were found to be expressed in lemmas and not in leaves. The Lem2 promoters were cloned and attached to the green fluorescent protein reporter gene (gfp). An epicarp-specific gene (Ltp6) was also discovered. The promoter for Ltp6 was likewise cloned and used to drive gfp expression. These promoters expressed gfp in the target tissues, as predicted, and will be used to target thionin expression. This research will ultimateley benefit barley farmers, maltsters and brewing companies by providing barley lines that are resistant to Fusarium.