P-386 - Role of a Host RNA-Binding Protein in Inducing FgDICER-2 and FgAGO-1 in F. graminearum Mycovirus Infection

RNA interference (RNAi) serves as a key defense mechanism in fungi against mycovirus infections. Despite the necessity of a sophisticated regulatory system for antiviral RNAi, little is known about the host factors involved in the transcriptional regulation of RNAi component genes. We transferred Fusarium graminearum virus 2 (FgV2) into putative transcription factor deletion mutant library and found that FgDICER-2 and FgAGO-1 were not fully induced in the GzC2H056 deletion mutant despite of successful FgV2 infection using RT-qPCR. This defect was rescued through gene complementation and overexpression. In the wild-type strain, GzC2H056 expression was strongly induced—over 70-fold—following FgV2 infection compared to the virus-free state. RNA recognition motifs and CCCH zinc finger domains were predicted in N-terminal region of GzC2H056 based on NCBI and CIS-BP RNA database, and we confirmed RNA binding property of GzC2H056 by electrophoretic mobility shift assay. Further analysis using truncated overexpression mutants and RT-qPCR demonstrated that the N-terminal region containing RNA-binding domains is critical for the induction of FgDICER-2 and FgAGO-1. Additionally, GFP-fused GzC2H056 localized in the cytoplasm, forming distinct foci. Taken together, we identified GzC2H056 as a host factor with RNA-binding affinity that plays a crucial role in the transcriptional induction of FgDICER-2 and FgAGO-1 during mycovirus infection in F. graminearum.