Integrative analysis of alkaloid biosynthesis and distribution in Polygonatum cyrtonema Hua: Using advanced imaging and molecular techniques

Polygonatum cyrtonema Hua rhizomes are rich in various bioactive compounds with numerous biological activities, and almost 80% of its production in China is consumed as food. The metabolite profiles and regulatory network of alkaloids in four-year-old P. cyrtonema are not currently available. In this study, phytochemical, antioxidant, metabolome, and transcriptome analyses were integrated to investigate the dynamic accumulation and regulatory network in four-year-old rhizomes. To elucidate the spatial distribution and biosynthesis of alkaloids, we employed cutting-edge techniques, including MALDI-MSI (identified 41 alkaloids) and LC-MS/MS (identified 260 alkaloids). These metabolites show distinct localization patterns and a significant increase in the alkaloid content up to a 2.8-fold change, and a rise in radical scavenging activities (DPPH, ABTS, FRAP) with increase in growth and concentration, with a significant positive correlation ( P < 0.001), and R² values with a significant proportion of over 92% variability in antioxidant capacity. A comparative analysis confirmed the consistent detection of 10 alkaloids by both methods, underscoring their biological relevance. Additionally, the metabolomic and transcriptomic profiling identified key genes involved in alkaloid biosynthesis (PNAE, AOC3/2, tynA, TR1, GOT1/2, and AGXT2). The core biosynthetic gene expression patterns were validated via qRT-PCR and showed reliable consistency in gene expression analysis with FPKM values, which revealed a strong positive relationship, with Pearson’s r value ranging from 0.592 to 0.9865 . This study deepens our understanding of alkaloid biosynthesis, spatial distribution, and developmental dynamics in the four-year-old P. cyrtonema rhizome, providing valuable insights for future medicinal quality and groundwork for industrial applications.