Submitted to: Plant Molecular Biology International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/28/2006
Publication Date: 8/22/2006
Citation: Skadsen, R.W., Patel, M., Federico, M.L., Abebe, T. 2006. Transformation to produce barley resistant to fusarium graminearum. Proceedings of the Plant Molecular Biology International Conference. p. 129.
Technical Abstract: The fungal pathogen Fusarium graminearum destroys barley and wheat crops by causing scab disease (Fusarium head blight, FHB). Spores infect seed spike tissues, leading to production of mycotoxins. There are no known barleys with biochemical resistance to Fusarium, although some have various levels of tolerance and avoidance. Genetic transformation with antifungal genes could provide Fusarium resistance, but it is necessary to 1) identify proteins toxic to Fusarium, 2) determine the route of infection, and 3) develop tissue-specific gene promoters in order to target the toxic proteins to the path of infection. We have found that Fusarium rapidly colonizes the ovary epithelial hairs that protrude from the tip of the seed. Colonization of the lemma (hull) also occurs but requires almost 48 h. The ovary epithelial hairs are continuous with the pericarp epithelium (epicarp), which supports rapid infection to the base of the developing seed. Surprisingly, no penetration of the starchy endosperm (just under the epicarp) occurs for weeks. A gene encoding a lectin-like protein, LEM2, is expressed in lemmas and not in leaves. Lem2 and 2b promoters were cloned and attached to the gfp (green fluorescent protein) reporter gene. An epicarp-specific lipid transfer protein gene (Ltp6) was also discovered. The promoter for Ltp6 was cloned and used to drive gfp expression in transformants. These and other promoters will be used to target thionin expression through genetic transformation using particle bombardment and Agrobacterium. We have tested two forms of barley thionin and found both to be toxic to F. graminearum. By leading to mycotoxin-free barley, these studies will ultimateley be beneficial to the malting and brewing industries and to barley producers.