Moderate CO2 Enrichment Enhances Saponin Accumulation in Panax japonicus by Activating Sugar Metabolism
Xiao Wang*, E Liang, Xiaohui Song, Deyan Li
College of Agriculture, Anshun University, Anshun, China
* Corresponding Author: Xiao Wang. Email: 
(This article belongs to the Special Issue: Plant Responses and Adaptations to Environmental Stresses)
Phyton-International Journal of Experimental Botany https://doi.org/10.32604/phyton.2026.075656
Received 05 November 2025; Accepted 29 December 2025; Published online 05 February 2026
Abstract
Three-year-old
Panax japonicus was exposed to elevated CO
2 concentrations using open-top chambers: ambient CO
2 (aCO
2), moderately elevated (e1CO
2, 550 μmol/mol), and highly elevated (e2CO
2, 750 μmol/mol). Gas exchange parameters, photosynthetic pigments, sugar accumulation, and total saponin content were measured to assess the effects of CO
2 enrichment on photosynthesis, sugar metabolism, and saponin biosynthesis. The e1CO
2 treatment significantly increased net photosynthetic rate (by 17.22% at 36 days and 69.62% at 92 days), chlorophyll a content, and soluble sugar, sucrose, and starch accumulation. Key sugar metabolism enzymes, including sucrose phosphate synthase (SPS), also showed enhanced activity. Consequently, underground rhizome total saponins rose significantly by 15.16%. In contrast, e2CO
2 initially (36 days) stimulated photosynthesis but lost this effect over prolonged exposure (92 days), with no significant impact on photosynthetic parameters, pigments, or sugar levels. Correlation analysis indicated that rhizome saponin content was positively associated with leaf sucrose levels and sucrose synthase (synthetic direction) activity. These findings suggest that moderate CO
2 elevation (e1CO
2) enhances
P. japonicus photosynthesis and sugar metabolism, driving greater saponin accumulation. However, high CO
2 (e2CO
2) has transient benefits, with stimulatory effects diminishing over time.
Keywords
Panax japonicus; elevated CO
2 concentration; photosynthetic characteristics; sugar metabolism; saponin accumulation
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