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Use of biotechnological tools to incorporate broad virus resistance into wheat

Monica Navia-Urrutia: Kansas State University

<div>Viruses are a serious threat to global wheat production. In Kansas, the wheat streak mosaic complex, caused by <em>Wheat streak mosaic virus</em> (WSMV), <em>Triticum mosaic virus</em> (TriMV), and <em>Wheat mosaic virus </em>(WMoV), ranked as the second most important disease of 2017, accounting for 5.6% yield loss. Control of the vector is not fully effective and few sources of resistance to these viruses have been identified. Viruses of the family <em>Potyviridae</em> (WSMV and TriMV) recruit the host eukaryotic translation initiation factors to complete their infection cycle. Our aim was to silence and edit the wheat initiation factors <em>eIF(iso)4E-2</em> and <em>eIF4G</em>, for conferring resistance to WSMV and TriMV. Calli of the susceptible cultivar ‘Bobwhite’ were independently bombarded with <em>eIF(iso)4E-2</em> and <em>eIF4G</em> RNAi expression vectors. Silenced lines were resistant to WSMV and TriMV in single and mixed infections, through multiple generations and in crosses with the variety ‘Karl 92’. Relative expression assays confirmed reduction in eIF(iso)4E-2 and eIF4G expression, and in viral titer. For the gene-editing approach, four regions were selected in each gene to be targeted by Cas9. ‘Bobwhite’ calli were bombarded with target-specific sgRNA scaffold vectors and vectors carrying <em>Cas9</em>. Sixty-four independent biolistic experiments have been completed. Regeneration of mutants, performance against viruses, and the effectiveness of these tools to incorporate virus resistance into wheat, will be discussed.</div>