Submitted to: Barley Improvement Conference Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 12/30/2008
Publication Date: 1/6/2009
Citation: Skadsen, R.W., Patel, M., Federico, M.L., Abebe, T. 2009. Fusarium-Resistant Barley Through Genetic Transformation. 37th Barley Improvement Conference Proceedings. January 6-7, 2009, San Diego, California. p. 10. Interpretive Summary:
Technical Abstract: Genetic transformation with antifungal genes could provide barley with the resistance to Fusarium graminearum (F.g.). More molecular studies are needed to 1) identify effective anti-Fusarium genes, 2) develop more tissue-specific gene promoters to target expression to the path of infection, and 3) determine the subcellular route(s) of infection. Within 7 h after inoculation, F.g. colonizes the ovary epithelial hairs at the tip of the seed and rapidly grows downward along the pericarp epithelium (epicarp). Colonization of the lemma (seed hull) also occurs but is much slower. Surprisingly, no penetration of the endosperm occurs for at least two weeks. Thus, gene promoters to target transgene expression to the epicarp and the lemma are needed. We have developed several promoters, but more are needed, and more fine tuning of these will be required. The ultimate goal is to develop promoters that are not only tissue-specific but are also inducible by infection. It would also be desirable to incorporate targeting sequences that will direct anti-Fusarium products to the subcellular routes of infection (vacuole, apoplast, etc.). The list of potential anti-Fusarium genes grows as new strategies, such as microarray analysis, are developed. However, not every host gene upregulated by F.g. is a defensive gene. Effective pre-screening of these genes is needed to narrow the list of candidates, prior to the lengthy process of barley transformation. Initial efforts in barley involved genes encoding proteins that interact directly with fungal hyphae (including thionins, tlps, chitinase, glucanase, or combinations of these). Newer strategies include detoxifying DON or exporting it from the cell. Several transformants had promising results in greenhouse trials, but so far, none has been successful in field trials. We have transformed Golden Promise barley with the gene for a thionin found at very low levels in the lemma. Lemmas of transformants produce high levels of the protein. A simple cut leaf assay was used to test transformants for resistance to F.g. Preliminary tests are promising.