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),550μmol/mol),and highly elevated(e2CO_(2),750μmol/mol).Gas ex...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),550μmol/mol),and highly elevated(e2CO_(2),750μmol/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.展开更多
基金funded by the Guizhou Province Technology Plan Project,Qiankehe Basic-ZK[2023]General 023,Key 002 and Guizhou Province Project for the Growth of Young Scientific and Technological Talents in General Higher Education Institutions,QianJiao He Foundation,Grant No.(2022)029.
文摘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),550μmol/mol),and highly elevated(e2CO_(2),750μmol/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.
