A novel secreted protein FgHrip1 from Fusarium graminearum triggers immune responses in plants1

Abstract

Fusarium graminearum, the primary pathogenic fungus responsible for Fusarium head blight (FHB) in wheat, secretes abundant chemical compounds that interact with host plants. In this study, a secreted protein FgHrip1, isolated from the culture filtrate of F. graminearum, was found to induce typical cell death in tobacco. The FgHrip1 gene was then cloned and expressed in Escherichia coli. Further bioassay analysis showed that the recombinant FgHrip1 induced early defense induction events, such as reactive oxygen species (ROS) production, callose deposition, and up-regulation of defense-related genes in tobacco. Furthermore, FgHrip1 significantly enhanced immunity in tobacco seedlings against Pseudomonas syringae pv. tabaci 6605 (Pst. 6605) and tobacco mosaic virus (TMV). FgHrip1-treated wheat spikes also exhibited defense-related transcript accumulation and developed immunity against FHB infection. Whereas the expression of FgHrip1 was induced during the infection process, the deletion of the gene impaired the virulence of F. graminearum. Our results suggest that FgHrip1 triggers immunity and induces disease resistance in tobacco and wheat, thereby providing new insight into strategy for biocontrol of FHB.