Paeonia ostii ‘Fengdan’ is an important woody ornamental crop that integrates ornamental value with practical applications in oil production and traditional medicine. The fruit pods of tree peony are rich in terpenoids, flavonoids, and phenolic acids which are valuable secondary metabolites yet frequently discarded as waste. Oxypaeoniflorin is a significant terpenoid secondary metabolite in tree peony; however, the temporal accumulation pattern of oxypaeoniflorin in tree peony fruit pods and the molecular mechanisms governing its biosynthesis remain incompletely understood. In this study, fruit pods of P. ostii ‘Fengdan’ were used as experimental materials. Samples from seven developmental stages (from 25 to 109 days after pollination) were collected and subjected to integrated analysis using non‐targeted metabolomics and transcriptomics approaches. A total of 1740 metabolites were identified through metabolomic profiling, among which 105 common differentially accumulated metabolites were screened. Oxypaeoniflorin was identified as the target metabolite, exhibiting a dynamic accumulation pattern from stage 25 DAP to 109 DAP and reaching its peak level at stage 81 DAP. Through integrated weighted gene co‐expression network analysis (WGCNA) and Mfuzz clustering, two candidate genes associated with oxypaeoniflorin biosynthesis were identified: ZEP and UGT73B4. Based on integrated multi‐omics analysis, this study elucidated the temporal accumulation pattern and the underlying regulatory mechanisms of oxypaeoniflorin biosynthesis, which provides a theoretical basis for the high‐value utilization of tree peony fruit pods and further studies on monoterpenoid glycoside biosynthesis.
Ting-Ting Zhou, Ding-Ding Zuo, Di Yang et al.· Physiologia Plantarum : An I...· 0 citations
The flower type of tree peony is a crucial ornamental trait, determining both its ornamental and economic value. However, double-flower cultivars are relatively scarce, and the underlying regulatory mechanisms governing double flower formation remain unclear. Here, based on the transcriptome analysis of different floral organs from three flower types of ‘Zhaofen’, a total of 40 824 genes were identified, and the key genes PsuAP3L, PsuAGL6, and PsuSUS3 were screened out by integrating weighted gene co-expression network analysis (WGCNA), with high expression observed in the petals of double-petal flowers. Overexpression of PsuAP3L transformed the stamens into petal-like structures in Arabidopsis thaliana and significantly increased petal number in tree peony, while silencing it led to a reduction in petal number. Notably, both in vivo and in vitro experiments have demonstrated that PsuAGL6 could directly bind to the CArG-box element in the PsuAP3L promoter, positively regulating its transcription and thereby increasing the petal number. Furthermore, PsuAP3L can directly bind to the promoter of sucrose synthase PsuSUS3 and activate its expression through transcriptional activation. Transient overexpression and silencing experiments confirmed that both PsuAP3L and PsuAGL6 affect petal number by regulating PsuSUS3, thereby promoting double flower formation in tree peony. In addition, application of exogenous sucrose solution (1.5 g·L−1) effectively increases the number of petals in tree peony. This study demonstrates that the PsuAGL6-PsuAP3L-PsuSUS3 module regulates the double-flower trait in tree peony by promoting stamen petaloidy, thereby providing a theoretical foundation and practical strategies for breeding novel flower types.
