PnWRKY38-PnSUS1 axis regulates the biosynthesis of Panax notoginseng saponins

Abstract

Sucrose synthase (SUS) is a pivotal enzyme bridging primary carbon metabolism and secondary biosynthesis in plants. In Panax notoginseng , we demonstrate that sucrose synthase 1 (PnSUS1) serves as a metabolic bottleneck for saponin glycosylation by supplying UDP-glucose. PnWRKY38 was identified as a WRKY transcription factor whose expression correlated with both PnSUS1 and saponin accumulation. Overexpression of PnWRKY38 could up-regulate PnSUS1 expression by 3.5-fold, increase SUS enzyme activity by 2.8-fold, and elevate UDP-glucose pools by 68%. Consequently, the total content of ginsenosides Rg1, Rb1, and Rd rose by 2.1–2.4-fold. Conversely, PnSUS1 or PnWRKY38 suppression reduced UDP-glucose available and saponin biosynthesis by > 50%. Y1H and luciferase assays indicated that PnWRKY38 directly activated PnSUS1 expression by binding to W-box motifs in its promoter. These results not only illustrate the specific function that PnSUS1 executes in UDPG biosynthesis but also reveal a new WRKY transcriptional regulatory module regulating notoginsenosides production.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (82360742), Noncommunicable Chronic Diseases-National Science and Technology Major Project (2023ZD0506606), Key Project at Central Government Level: The Ability Establishment of Sustainable Use for Valuable Chinese Medicine Resources (2060302) and F.G. was supported by Yunnan Ten Thousand Talents Plan (Young & Elite Talents Project).

Author contributions

F.G. and X.C. designed the experiments; Q.C. performed the experiments; Q.C., X.W., Y.Q., and N.L. analyzed the data; Q.C. wrote the paper; and all authors reviewed the manuscript.

Data availability

All data supporting the results of this study are presented in the manuscript, including Supplementary information. The datasets generated or analyzed during the current study are available from the corresponding author on reasonable request.

Conflicts of interest statement

The authors declare that they have no conflict of interest.

Supplementary material

Supplementary material is available at Horticulture Research online.

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