Integrated transcriptomic and WGCNA analyses reveal coordinated regulation of pyrethrin biosynthesis and salt stress response in pyrethrum (Tanacetum cinerariifolium)

Tanacetum cinerariifolium is widely cultivated as both an industrial and ornamental crop and is valued for its production of natural insecticidal pyrethrins, which are important in botanical pesticide production. However, how environmental stress affects pyrethrin yield remains unclear. Here, we employed physiological measurements, transcriptome profiling, weighted gene co-expression network analysis (WGCNA), and qRT-PCR to examine how T. cinerariifolium responds to salt stress. Salt stress triggered tissue-specific antioxidant responses, superoxide dismutase (SOD) and catalase (CAT) activities generally increased with salinity, peroxidase (POD) activity peaked under control conditions, and malondialdehyde (MDA) content declined, with distinct trends in leaves and roots. WGCNA identified the MEyellow module (922 genes) as being strongly positively correlated with salt stress and pyrethrin accumulation. Protein-protein interaction (PPI) analysis screened DXS ( 1-deoxy- D -xylulose-5-phosphate synthase ), ZEP ( zeaxanthin epoxidase ), and ENO2 ( enolase 2 ) as central nodes involved in carbon metabolism, abscisic acid (ABA) biosynthesis, as well as pyrethrin accumulation. ABA-related and pyrethrin-biosynthesis-related genes showed tissue-specific expression patterns, with general upregulation in leaves but downregulation or feedback inhibition in roots. Consistent with this pattern, pyrethrin content increased in leaves under salt treatment, suggesting that salt-induced metabolic adjustment helps maintain pyrethrin biosynthesis under stress. Overall, these results suggest that salt stress triggers adaptive metabolic adjustments in T. cinerariifolium , coordinating ABA signaling, carbon metabolism, and tissue-specific gene expression to maintain pyrethrin production under stress. This regulatory framework provides a basis for breeding salt-tolerant, high-pyrethrin T. cinerariifolium varieties.