The Dynamic Changes in Biosynthesis and Spatiotemporal Distribution of Phytohormones Under Jasmonic Acid Treatment Provide Insights into Hormonal Regulation in <i>Sinopodophyllum hexandrum</i>

<i>Sinopodophyllum hexandrum</i> (Royle) Ying, the only species of Sinopodophyllum in <i>Berberidaceae</i>, is an endangered traditional Tibetan medicine. The harsh plateau growth environment makes <i>S. hexandrum</i> tough to breed and meet the global demand for clinical medications such as podophyllotoxin (PTOX) and etoposide. Jasmonic acid (JA) is acknowledged as a key phytohormone that modulates stress responses by activating defense mechanisms and promoting the production of specialized metabolites, which offers valuable insights for developing varieties that are more resilient to stress or yield higher amounts of secondary metabolites. In this study, JA treatment was used as a simulated source of stress to investigate the spatiotemporal changes in phytohormones, such as JA, <i>cis</i>-(+)-12-oxo-10, 15(<i>Z</i>)-phytodienoic acid (<i>cis</i>-(+)-OPDA), and abscisic acid (ABA), and transcriptional regulation following hormonal regulation in intact plants. Some correlations through changes in phytohormone levels and the expression level of related signaling pathway genes were observed to confirm the overall regulatory effect after the JA treatment. Furthermore, the JA treatment caused the differential expression of various genes including transcription factors (TFs), of which the most typical one is myelocytomatosis oncogene like protein 2 (MYC2), <i>ShMYC2_3</i>. Therefore, we proposed that a plant hormone-mediated regulatory network exists endogenously in <i>S. hexandrum</i>, enabling it to respond to JA treatment. This study provides a new direction for the germplasm improvement and the sustainable utilization of <i>S. hexandrum</i> when facing exogenous stimulation.