A molecular switch OsWRKY10-OsVQ8 orchestrates rice diterpenoid phytoalexin biosynthesis for broad-spectrum disease...

Rice plants synthesize a unique group of diterpenoid phytoalexins (DPs) that exhibit broad-spectrum antimicrobial activities and are biosynthesized by enzymes encoded by three biosynthetic gene clusters. However, the regulatory mechanisms of their biosynthesis remain unclear. Here, the regulatory roles of the transcription factor OsWRKY10 and its interacting VQ motif-containing protein OsVQ8 in DPs biosynthesis and disease resistance were investigated via genetic and biochemical analyses. Their CRISPR/Cas9-mediated knockout and over-expressing (OE) lines, as well as crossed lines WRKY10_OE/vq8, were generated. OsVQ8 phosphorylation by mitogen-activated protein kinase (MAPK) cascades was examined. We found that OsWRKY10 co-expresses with and activates a specific set of genes involved in DPs biosynthesis, thereby enhancing DPs accumulation and disease resistance against both fungal blast and bacterial blight. We demonstrate that OsWRKY10 interacts with the VQ motif-containing protein OsVQ8, modulating DPs biosynthesis through OsVQ8 phosphorylation by the activated OsMKK4-OsMPK6 cascade upon perception of pathogen-associated molecular patterns. Our findings highlight how the interaction between OsVQ8 and OsWRKY10 serves as a molecular switch to regulate gene clusters and the entire pathway of DPs biosynthesis in rice and provides valuable insights for genetic engineering aimed at enhancing phytoalexin production and broad-spectrum disease resistance in staple food crops.