Transcriptome analysis reveals acetylsalicylic acid-mediated accumulation and regulatory network of piperine content in Piper nigrum L.roots

Black pepper (Piper nigrum L.) is widely used in food and medicine due to its high piperine content. However, recent studies have revealed that piperine synthesis and accumulation also occur in pepper roots, offering a new pathway for sustainable piperine production.Acetylsalicylic acid (ASA), as a plant signaling molecule, is extensively involved in regulating plant secondary metabolism. Nevertheless, whether it regulates the synthesis of piperine in pepper roots remains to be elucidated. This study evaluated the effects of exogenous ASA at different concentrations (0, 50, 100, 200 µM) on piperine content in pepper roots. We found that ASA regulates piperine accumulation in a concentration-dependent manner, peaking at 50 µM. Based on RNA-seq data and weighted gene co-expression network analysis (WGCNA), it was further determined that 50 µM ASA treatment promotes piperine accumulation in roots by significantly upregulating key genes in the piperine biosynthesis pathway (e.g., PnADT, PnCSS, PipBAHD1). Concurrently, it reshapes carbon metabolism flows, regulates sugar metabolism processes, and modulates endogenous hormone synthesis and signaling pathways, synergistically promoting root growth and development while expanding piperine synthesis sites. This study reveals the molecular basis by which low-concentration ASA enhances piperine content through dual mechanisms—activating the piperine synthesis pathway and promoting root development—from the perspective of multi-gene, multi-pathway coordinated regulation. It provides theoretical support for utilizing exogenous hormones to regulate piperine production.