Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/8/2019
Publication Date: 12/10/2019
Citation: Hao, G., McCormick, S.P., Naumann, T.A., Kim, H.-S., Proctor, R. 2019. The effector FgNls1 is required for full virulence of Fusarium graminearum [abstract].
Technical Abstract: Effectors produced by plant pathogenic fungi play important roles in suppression of immunity and promotion of disease in plants. Fusarium head blight (FHB), caused by the fungus Fusarium graminearum, is one of the most devastating diseases of wheat and barley worldwide. In addition to reducing crop yield and quality, F. graminearum can contaminate grain with trichothecene mycotoxins such as deoxynivalenol (DON). Based on genome sequence data, F. graminearum is predicted to produce hundreds of effectors. However, the functions of most of these effectors remain unknown. In this study, we characterized an effector FgNls1 (FGSG_04563), which is predicted to contain multiple eukaryotic nucleus localization signals (NLS). A fusion protein of GFP and FgNls1 accumulated in nucleus of Nicotiana benthamiana via Agrobacterium-mediated transient expression. Co-immunoprecipitation assays using GFP-FgNls1 fusion protein confirmed its nuclear localization in N. benthamiana but did not identify its plant target in N. benthamiana. FgNls1 also suppressed cell death induced by Bax when co-expressed with Bax in N. benthamiana. Expression of FgNLS1 was induced during development of FHB in wheat, suggesting a role in pathogenesis. Deletion mutants of FgNLS1 displayed similar growth and DON production as wild-type parent strain PH-1. Compared to PH-1, Fgnls1 mutants significantly reduced their ability to cause FHB and DON contamination in infected wheat tissue. These results indicate that FgNls1 contributes to pathogenesis of F. graminearum on wheat by suppressing plant immune responses. Further experiments are underway to identify FgNls1 plant target and elucidate the mode of action of FgNls1 during FHB.