PmWRKY-10 Enhances Pine Wilt Disease Resistance by Promoting Pinosylvin Monomethyl Ether Biosynthesis Through Transcriptional Activation of PmPMT2-1.

Pine wilt disease (PWD), caused by the pine wood nematode (PWN, Bursaphelenchus xylophilus), poses a severe threat to global pine forests. Plants can enhance their resistance to external stresses by eliciting secondary metabolites; however, the transcriptional regulatory mechanisms governing this defence response in pines remain largely unexplored. Here, we report a novel defence regulatory module in Pinus massoniana. PmWRKY-10 may participate in PWN resistance by regulating the biosynthesis of the nematicidal metabolite pinosylvin monomethyl ether (PME). We first demonstrated that PME accumulation is closely linked to resistance in P. massoniana and provided evidence that PME exhibits direct and potent nematicidal activity against PWN in vitro. By integrating multi-omics profiling with weighted gene co-expression network analysis (WGCNA), we identified PmPMT2-1 as a key candidate associated with PME biosynthesis and accumulation, while recognizing that it is unlikely to function as the sole rate-limiting determinant. Functional analyses demonstrated that PmPMT2-1 overexpression promoted PME accumulation and enhanced resistance, whereas silencing the gene impaired both processes. Mechanistically, we identified PmWRKY-10 as an upstream transcriptional activator that directly binds to the W-box element in the PmPMT2-1 promoter, inducing its transcription. Our work delineates a complete PmWRKY-10→PmPMT2-1→PME transcriptional-metabolic pathway that is essential for stilbene-based resistance in pine. This discovery not only provides fundamental insights into the inducible defence mechanisms of conifers but also identifies key genetic targets for breeding resistant varieties and developing sustainable forest management strategies.