A novel peptide encoded by a rice circular RNA confers broad‐spectrum disease resistance in rice plants

Summary Circular RNAs (circRNAs) are a significant class of endogenous RNAs that exert crucial biological functions in human and animal systems, but little is currently understood regarding their roles in plants. Here, we identified a circRNA originating from the back‐splicing of exon 4 and exon 5 of a rice gene, OsWRKY9 , and named it circ‐WRKY9. It is upregulated in rice stripe mosaic virus (RSMV)‐infected rice plants. Notably, circ‐WRKY9 contains two open reading frames with an internal ribosome entry site. We found that circ‐WRKY9 encoded a peptide of 88 amino acids (aa) and named it WRKY9‐88aa. Overexpression of WRKY9‐88aa suppresses RSMV infection in rice plants, with increased reactive oxygen species production. Furthermore, WRKY9‐88aa enhances resistance to blast disease and bacterial leaf blight, suggesting its potential to provide broad‐spectrum disease resistance. Our findings provide the first evidence of a peptide encoded by a circRNA in planta and highlight its potential application to control a wide spectrum of plant diseases.