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

Authors: LIN, XIANHUI - Fujian Agricultural & Forestry University; DING, CHAOHUI - Fujian Agricultural & Forestry University; XIAO, WEI - Fujian Agricultural & Forestry University; WANG, JINHAO - Fujian Agricultural & Forestry University; LIN, ZHUO - Fujian Agricultural & Forestry University; SUN, XINLI - Fujian Agricultural & Forestry University; LI, SUHUA - Fujian Agricultural & Forestry University; Pan, Zhiqiang; ZENG, RENSEN - Fujian Agricultural & Forestry University; SONG, YUANYUAN - Fujian Agricultural & Forestry University

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2025
Publication Date: 3/17/2025
Citation: Lin, X., Ding, C., Xiao, W., Wang, J., Lin, Z., Sun, X., Li, S., Pan, Z., Zeng, R., Song, Y. 2025. A molecular switch OsWRKY10-OsVQ8 orchestrates rice diterpenoid phytoalexin biosynthesis for broad-spectrum disease resistance. New Phytologist. https://doi.org/10.1111/nph.70072.
DOI: https://doi.org/10.1111/nph.70072

Interpretive Summary: Rice plants synthesize a distinctive group of diterpenoid phytoalexins (PDs) that exhibit broad-spectrum antimicrobial activity. However, the regulatory mechanisms of their biosynthesis remain unclear. In this study, we evaluate the transcription factor OsWRKY10, a key regulator of the downstream of jasmonate signaling pathway. We find that OsWRKY10 co-expresses with and activates a set of genes involved in diterpenoid phytoalexin biosynthesis, thereby enhancing disease resistance. We demonstrate that OsWRKY10 interacts with the VQ motif-containing protein OsVQ8, modulating PD biosynthesis through OsVQ8 phosphorylation. Our findings highlight how interaction between OsVQ8 and OsWRKY10 serves as a molecular switch in the biosynthesis of PDs and provide valuable insights for genetic engineering aimed at enhancing phytoalexin production and broad-spectrum disease resistance in essential crops.

Technical Abstract: Rice (Oryza sativa L.) produces a unique group of diterpenoid phytoalexins (DPs) with broad-spectrum anti-microbial activity. However, the regulatory mechanisms of their biosynthesis remain unclear. In this study, we demonstrated that the transcription factor OsWRKY10 interacts with the VQ motif-containing protein OsVQ8 to regulate the biosynthesis of DPs and disease resistance in rice. Expression levels of biosynthetic genes of DPs and their precursors were significantly higher in OsWRKY10 overexpressing (OE) plants, but lower in the CRISPR/Cas9-mediated knock-out mutant. OsWRKY10 knock-out and OsVQ8-overexpressing plants displayed increased susceptibility to both Xanthomonas oryzae pv. oryzae (Xoo) and two isolates of Magnaporthe oryzae, while OsWRKY10-overexpressing and OsVQ8 knockout plants exhibited increased resistance to these pathogens. OsWRKY10 knock-out reduced the accumulation of DPs while its overexpression enhanced DPs accumulation. In vitro and in vivo assays showed that OsVQ8 protein interacted with OsWRKY10 to inhibit its transcription activity. Mutated OsVQ8 in the OsWRKY10-OE background further enhanced disease resistance, suggesting that OsVQ8 functions as a transcriptional repressor. ChIP-qPCR and EMSA analyses demonstrated that OsWRKY10 directly bound to the W-box elements in the promoters of two key DPs biosynthetic genes OsCPS2 and CYP99A2. Furthermore, OsVQ8 interacted with OsMPK6 and phosphorylated by the activated OsMKK4-OsMPK6 cascade. Both bacteria- and fungi-derived elicitors accelerated the phosphorylation and degradation of OsVQ8 in rice protoplasts. Our findings identify a molecular switch consisting of OsVQ8-OsWRKY10 and phosphorylated by pathogen-trigged MAPK cascade to regulate de novo DPs synthesis and broad-spectrum disease resistance in rice.