-Specific Orphan Gene Confers Clubroot Resistance in Arabidopsis via Phenylpropanoid Pathway Activation.

Clubroot disease, caused by , poses a serious threat to global crop production. Orphan genes (OGs), which are species or lineage-specific and lack detectable homologs in other taxa, have been implicated in various biotic stress responses. Here, we identified a novel -specific orphan gene, designated , that confers resistance to clubroot. Heterologous overexpression of in significantly enhanced resistance to . Transcriptomic profiling of -overexpressing lines highlighted the essential role of the phenylpropanoid biosynthesis pathway, showing upregulation of key lignin synthesis genes (including and ) and defense-related regulators ( and ). Weighted co-expression network analysis further corroborated the link between -mediated resistance and enhanced lignin deposition and cell wall reinforcement. Our findings establish as a -specific orphan gene that enhances clubroot resistance via phenylpropanoid pathway activation. These results highlight the potential of orphan genes as novel genetic resources for breeding clubroot-resistant varieties, offering a sustainable strategy to mitigate yield losses caused by this devastating disease.