Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/8/2020
Publication Date: 8/12/2020
Citation: Hao, G., McCormick, S.P., Usgaard, T.R., Tiley, H.C. 2020. Fusarium graminearum effectors suppress plant immunity and play a quantitative role during infection. [abstract].
Technical Abstract: Fusarium graminearum causes Fusarium head blight (FHB) on wheat and barley. It produces the mycotoxin deoxynivalenol (DON), which functions as a virulence factor and causes grain contamination. F. graminearum secretes hundreds of effectors that can interfere with plant immunity and promote FHB. However, the functions of many of these effectors remain unknown. We investigated the expression of three F. graminearum effector-encoding genes and their roles during FHB development. Our results revealed that effectors FGSG_01831, FGSG_03599 and FGSG_12160, were highly induced during wheat head infection. We generated single gene deletion mutants for these three effectors and performed FHB virulence assays with point and dip inoculations. The deletion mutants of all three effectors had reduced FHB spread in wheat heads but none of the reduction was significant by statistical analysis. In contrast, deletion mutants of FGSG_01831 caused significantly less FHB initial infection and produced significantly less DON in wheat and barley heads. The three effectors were transiently expressed in Nicotinana benthamiana leaves. N. benthamiana leaves expressing these effectors significantly reduced the production of reactive oxygen species induced by chitin, but not by flg22. Furthermore, FGSG_01831 and FGSG_03599 significantly suppressed Bax-induced cell death when co-expressed with Bax in N. benthamiana leaves. Our study provides new insight into the functions of the F. graminearum effectors and suggests that they may play a quantitative role during F. graminearum infection.