RNA granule-associated regulation of antiviral RNA interference by the RNA-binding E3 ubiquitin ligase in Fusarium graminearum

ABSTRACT

RNA interference (RNAi) is a major antiviral defense in fungi, yet the regulatory mechanisms governing this pathway remain incompletely characterized. In this study, we identified GzC2H056 as a host factor required for the induction of FgDICER-2 and FgAGO-1 in Fusarium graminearum during infection by the Fusarium graminearum virus 2 (FgV2). GzC2H056 expression is transcriptionally induced upon FgV2 infection and exhibits both RNA-binding and E3 ubiquitin ligase activity in vitro. Fluorescence tagging showed that GzC2H056 co-localizes with poly(A)-binding protein 1 and 5'-to-3' exoribonuclease 1, which are markers of stress granules and P-bodies, respectively. RNA-sequencing analysis further revealed that GzC2H056 regulates the expression of genes involved in RNA metabolism and transcription factors linked to RNAi induction. Together, these findings identify GzC2H056 as a regulator of antiviral RNAi in fungi, suggesting that RNA granule-associated mechanisms contribute to fungal defense against mycoviruses.