Expression profiling and function analysis of PmLAS highlight the involvement in regulating resin yield of Pinus massoniana

Masson pine ( Pinus massoniana L.) is a significant resin-producing tree. Its resin, rich in monoterpenes, sesquiterpenes, and diterpenes, is commercially valuable. The diversity of these terpenes is influenced by the TPS-d subfamily, unique to conifers. We identified 44 TPS-d members through transcriptomic data and examined the expression of 8 TPSs . Most TPSs are broadly expressed across different tissues, whereas a minority nearly unexpressed in specific tissues. The differential expression of TPSs under diverse environmental conditions indicates that these factors may influence terpenoid synthesis. In masson pine, PmLAS expression is significantly positively correlated with resin yields. We also assessed the resin components in samples with different resin yields and conducted a correlation analysis between resin components and resin yield. Among these components, levopimaric acid, isopimaric acid, and neoabietic acid highly demonstrated a significant positive correlation with resin yield. We employed VIGS to knock down PmLAS expression in 3-year-old masson pine seedlings to further explore its role in terpenoid synthesis. This resulted in decreased levopimaric acid content and reduced resin yield. To explore the molecular regulation of PmLAS , its promoter sequence was obtained. Through a yeast one-hybrid assay, a transcription factor PmMYB6 was identified. Dual luciferase assays revealed that PmMYB6 could bind to the PmLAS promoter and inhibit its expression. This research provides valuable understanding of TPSs ' involvement in terpene metabolism. • The expression patterns of 8 TPSs were analyzed, showing varied gene expression across tissues and environmental conditions. • The expression of the PmLAS and the content of levopimaric acid showed a strong positive correlation with resin yield. • VIGS experiments showed that knock down PmLAS expression reduced levopimaric acid and resin yield. • The PmMYB6 transcription factor can inhibit the expression of the PmLAS .