Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/17/2003
Publication Date: 12/10/2003
Citation: Federico, M.L., Skadsen, R.W., Kaeppler, H.F. 2003. A barley ltp promoter for targeting transgene-mediated disease resistance. XII Plant and Animal Genome Conference Proceedings. p. 97.
Technical Abstract: Transgene-mediated resistance is a promising means for controlling crop diseases. A successful strategy should combine the use of effective pathogenesis-related (PR) or resistance cascade regulatory genes under appropriate tissue-specific promoters. We have cloned and characterized the novel barley gene, Ltp6, which is highly expressed in the pericarp epidermis. This is one of the first spike tissues to be colonized by Fusarium graminearum, the main causal pathogen of Fusarium head blight (FHB), a devastating cereal disease. Expression analyses showed that this lipid transfer protein (LTP) gene is also highly expressed in the coleoptile and embryo, but not in leaves, stems, roots or other spike tissues. In addition, Ltp6 mRNA levels increase during ABA, SA, NaCl and cold treatments in seedling tissues. Series of promoter deletions were studied in transient expression assays using sgfp as a reporter. Real-time PCR was used to assess the level of transcription conferred by the different promoter constructs. All constructs containing at least 191 bp of upstream sequence, and 83 bp of 5'UTR, retained most of the promoter activity. Deletion of a 64 bp fragment (-191/-127) resulted in an 80% drop in expression. The role of a MYC- and several MYB-binding sites in the combinatorial control of Ltp6 transcription is currently under investigation by substitution mutant analysis. Spatial, temporal and inducible patterns of expression of the native and reporter genes in control and transgenic barley plants will be discussed.