Submitted to: National Fusarium Head Blight Forum Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 12/7/2002
Publication Date: 12/7/2002
Citation: Skadsen, R.W., Abebe, T., Federico, M.L., Kaeppler, H.F., Henson, C.A. 2002. Strategies for combating fusarium in barley through gene expression targeting, metabolic profiling and signaling analysis. National Fusarium Head Blight Forum Proceedings. p. 41. Interpretive Summary:
Technical Abstract: Several basic studies must be undertaken in order to understand the interactions between Fusarium graminearum and its barley and wheat hosts: 1) Gene promoters are needed to target the expression of antifungal protein genes to organs that are initially colonized by F.g., 2) Metabolic profiling must be developed to determine which metabolites are extracted from host tissues, and 3) It is important to understand the signaling pathway involved in host perception of F.g. invasion and attempts to mount an effective response. We have previously produced a gene promoter (Lem 1) that is specific for the young lemma/palea. More recently, Tilahun Abebe has used the suppressive subtractive hybridization method to identify genes expressed in lemmas/paleas but not in flag leaves. This led to the development of Lem2, which is specific to the lemma/palea of developing seeds during the period from endosperm elongation through the dough stage. Maria Laura Federico has developed a promoter (EpiLTP) that has preferential activity in the pericarp epithelium. A vector (Ala/gfp) was developed by Jianming Fu to test coding sequences of genes in a transient system, prior to their use in stable transformation. This has been applied to the expression of the anti-Fusarium gene Hth1 of barley. Portions of the Hth1 coding sequence were linked to a polyalanine bridge, followed by gfp. This showed that the failure of this endosperm protein to be produced in lemmas resides with sequences encoding the mature peptide. GC-MS by Cynthia Henson showed that early infection of the lemma and pericarp involves accumulation of metabolites that could be essential to fungal metabolism. In particular, metabolites know to be involved in appressorium turgor pressure (trehalose, mannitol and glycerol) were found. Our studies have shown that no alpha-amylase accompanies infection, even when infections are very heavy. We are examining whether the most obvious substrate (starch) is ever mobilized during infection, and we are attempting to develop a metabolic profile for infected tissue. Finally, it is not clear how barley reacts to the F.g. in the early stages of infection. Initial studies have shown that H2O2 is produced at the site of F.g. inoculation on the pericarp. Thus, barley may have the beginnings of a productive response that could be strengthened through breeding/molecular approaches.