Analysis of the TPS Gene Family and Functional Characterization of Rust Resistance in Zanthoxylum armatum DC

Background Zanthoxylum armatum is an economically important spice and medicinal plant whose industry is often severely threatened by rust disease. To investigate the role of the terpene synthase (TPS) gene in rust resistance, the ZaTPS gene (1206 bp) was cloned from the resistant cultivar 'Youkang'. Results Bioinformatics analysis revealed that it encodes an acidic, hydrophilic protein localized to the cytoplasm, lacking a signal peptide and transmembrane domains. Tissue-specific expression analysis showed that ZaTPS transcript levels were significantly higher in resistant plants and in leaves compared to susceptible ones. Transient overexpression and silencing of ZaTPS were successfully achieved in Z. armatum via Agrobacterium -mediated transformation. Functional studies demonstrated that overexpression of ZaTPS significantly increased the content of a key terpenoid (linalool) in leaves and effectively inhibited the germination of rust spores. Concurrently, the expression of pivotal genes in the terpenoid biosynthesis pathway (e.g., DXP, DXR, IPP) was significantly upregulated in overexpression plants. Following rust inoculation, plants overexpressing ZaTPS exhibited significantly lower disease incidence and severity index compared to controls, indicating enhanced resistance, whereas silenced plants showed increased susceptibility. Furthermore, ZaTPS expression positively regulated the activities of antioxidant enzymes (CAT, SOD, POD) and reduced the accumulation of malondialdehyde (MDA), thereby bolstering cellular defense capacity. Conclusions Overall, ZaTPS plays a crucial positive regulatory role in the rust resistance of Z. armatum by promoting terpenoid (particularly linalool) biosynthesis and enhancing the antioxidant defense system. This study provides important theoretical foundations for elucidating the molecular mechanisms of rust resistance in Z. armatum and for breeding new resistant cultivars.