Title: Down with DON: Strategies for precise transgene delivery and rnai-based suppression of fusarium Authors
Submitted to: National Fusarium Head Blight Forum Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 8, 2013
Publication Date: N/A
Technical Abstract: Transgenic strategies can effectively supplement other methods for controlling Fusarium head blight (FHB). Impediments to deploying FHB-resistant transgenic barley include a long time-frame for creating and testing transgenes in barley, imprecise transgene insertions that lead to unstable gene expression, a poor understanding of exactly how to attack Fusarium, and negative public perceptions. Advances in Fusarium genetics have elucidated the genome sequence and genes critical to pathogenicity. Increasingly detailed knowledge of RNA interference (RNAi)-based gene regulation enables strategies to target specific Fusarium genes. The delivery of single copy transgenes using modified Ds transposable elements or by site-specific recombination (aka recombinase-mediated cassette exchange, RMCE) enables precise transgene insertion, stable and heritable transgene expression, and production of transgenic plants without bacterial genes or selectable markers. These characteristics should mitigate some of the public concern about transgenic crops. We will use Ds-mediated and RMCE for the delivery of transgenes encoding double-stranded RNA (dsRNA) capable of RNAi-based suppression of key Fusarium genes involved in virulence and mycotoxin production such as Tri6. These transgenes initially will be tested directly in Fusarium, to facilitate rapid efficacy assessments. Transgenes showing efficacy in Fusarium will be converted to plant transformation vectors and introduced into Conlon. Progress towards these objectives includes: 1) creation of near-isogenic Conlon lines expressing Ac transposase, for Ds-delivery; 2) design and progress in the construction of Ds-delivery backbone vectors; 3) design and construction of the TAG or recombination site platform vector for RMCE; and 4) the regeneration of fertile Conlon plants containing the TAG recombination site.