Transcriptomics and Metabolomics Analyses Reveal New Insights Into Cold Resistance in <i>Paeonia Veitchii</i>

Paeonia veitchii is an important economic plant that is known for its exceptional medicinal value and for its remarkable tolerance to cold. However, the molecular mechanisms underlying its cold tolerance remain unclear. In this study, an integrated approach combining physiological analysis and multi-omics techniques was employed to investigate the metabolic pathways and molecular mechanisms involved in the cold stress response of P. veitchii. Metabolomic analysis revealed significant changes in the levels of 61 metabolites under cold stress, with prominent increases in polyamines (e.g., p-Coumaroylputrescine, +2.97-fold) and phenolic acids (e.g., Syringic acid, +3.69-fold). Transcriptomic profiling identified 22,525 DEGs, including 3852 genes enriched in cold adaptation pathways including plant hormone signaling, MAPK signaling, and glutathione metabolism. Key regulators of polyamine and phenolic acid metabolism were identified, including aldehyde dehydrogenase, arginine decarboxylase, polyamine oxidase (PAO), S-adenosylmethionine decarboxylase, and aspartate aminotransferase, with downregulation of PAO, promoting salidroside accumulation but simultaneously suppressing methylated indole-3-acetic acid. Moreover, the reduced accumulation of flavonoids may be linked to the expression of flavonoid 3'-monooxygenase. Furthermore, it was discovered that the ETH, JA-Ile, SA, and MAPK signaling pathways play an active role in the signaling of P. veitchii roots during the response to cold stress. This study offers valuable insights into the complex regulatory mechanisms that govern the cold stress response in P. veitchii roots, thereby establishing a theoretical basis for a better understanding of its response and adaptation mechanisms to cold stress.