Integration of MAPK signaling, terpenoid biosynthesis, and lncRNA regulation in the response of Pinus massoniana to pine wilt disease

Pine wilt disease (PWD), caused by the pine wood nematode (PWN), poses a serious threat to Pinus massoniana , yet the transcriptional responses and candidate molecular components remain incompletely understood. In this study, integrated Illumina RNA sequencing and PacBio Iso-Seq were used to investigate time-resolved transcriptional responses of a highly PWN-resistant P. massoniana family following nematode inoculation. Comprehensive transcriptome analysis revealed extensive and dynamic gene expression reprogramming across multiple infection stages. Differential expression and pathway enrichment analyses showed significant transcriptional induction and enrichment of MAPK signaling-related genes, with distinct components exhibiting temporally differentiated expression patterns. Weighted gene co-expression network analysis identified infection stage-associated modules containing resistance genes and long non-coding RNAs (lncRNAs), suggesting multilayered transcriptional regulation during nematode challenge. Notably, genes involved in terpenoid biosynthesis were strongly induced during infection. Sixty-two genes associated with terpenoid backbone formation and mono-, sesqui-, and diterpene biosynthesis were differentially expressed, with pronounced induction at early and late stages. RT-qPCR validation further showed that several terpene synthase genes, including CAS , IDS , APS1 , and APS2 , exhibited significantly higher expression in resistant families than in susceptible ones. Together, these results provide a time-resolved transcriptional framework describing the infection-responsive gene-expression patterns of highly resistant P. massoniana families and identify candidate genes potentially associated with PWD resistance for future functional validation.