人参中人参皂苷生物合成对水分调控的响应及其机制的初步研究

Preliminary study on response and its mechanism of ginsenoside biosynthesis in Panax ginseng to water regulation

探究土壤含水量对人参皂苷生物合成的影响,并从抗氧化酶系统和皂苷合成途径关键酶基因表达等角度阐释其机制。以三年生盆栽人参为试验材料,设置3个水分梯度,即饱和含水量的40%(W1),60%(W2),80%(W3),采用HPLC测定11种单体皂苷含量并以GAPDH为内参基因,利用实时荧光定量PCR分析皂苷合成途径中6个关键酶基因(HMGR,SS,β-AS,CYP716A47,CYP716A52v2,CYP716A53v2)表达量,同时对超氧化物歧化酶(SOD),过氧化物酶(POD),过氧化氢酶(CAT)活性和MDA含量进行测定。人参皂苷含量及生物量随土壤含水量的增大呈上升趋势,W3处理最适;PPD(Rb1,Rc,Rb2,Rd,Rh2,Rb3,Rg3),PPT(Rg1,Re,Rf)型人参皂苷,Ro及总皂苷均在8月30日达最大值,分别为9. 92,5. 48,0. 63 mg·g-1。整个调控期间W3抗氧化酶活性大于W1,MDA含量小于W1并且W3处理时β-AS,CYP716A47,CYP716A53v2基因表达量呈上升趋势而HMGR,SS基因在各个水分条件下表达量较稳定。经相关性分析得W3处理组HMGR,SS基因与PPD,PPT型人参皂苷及Ro呈现显著正相关,CYP716A52v2基因与Ro呈显著正相关,CYP716A47基因与PPD型人参皂苷呈极显著正相关;W1,W2处理时β-AS基因与PPD型人参皂苷呈极显著正相关。W3处理为最适水分,人参总皂苷及单体皂苷含量最高,各基因与皂苷含量相关性密切,更利于人参皂苷的积累。

The study is aimed to explore the effect of soil moisture content on ginsenoside biosynthesis and explain its mechanism from the perspectives of antioxidant enzyme system and gene expression of key enzymes in the pathway of ginsenoside synthesis.In the study,two years old Panax ginseng was used as the experimental material and three moisture gradient,40%of saturated water content(W1),60%(W2),80%(W3)were set up.The content of 11 monomeric saponins were determined by HPLC.With GAPDH as a reference gene,six key enzymes(HMGR,SS,β-AS,CYP716 A47,CYP716 A52 v2,CYP716 A53 v2)in ginseng saponin synthesis pathway expression were analyzed by fluorescent quantitative PCR and the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)activity and MDA content were also determined.With the increase of soil water,the content of ginseng saponin and biomass showed an increasing trend.PPD(Rb1,Rc,Rb2,Rd,Rh2,Rb3,Rg3),PPT(Rg1,Re,Rf)ginsenoside,Ro and total ginsenoside reached the maximum value on August 30,were 9.92,5.48,0.63 mg·g-1,respectively.During the whole regulation period,the antioxidant activity of W3 was greater than that of W1,and the MDA content was less than that of W1.At W3,expression levels ofβ-AS,CYP716 A47 and CYP716 A53 v2 showed an increasing trend,while HMGR and SS genes showed relatively stable expression levels under various water conditions.According to the correlation analysis,HMGR and SS genes in the W3 treatment group were significantly positively correlated with PPD,PPT ginsenoside and Ro,CYP716 A52 v2 gene was significantly positively correlated with Ro,and CYP716 A47 gene was significantly positively correlated with PPD ginsenoside.There was a significant positive correlation betweenβ-AS gene and PPD ginsenoside in W1 and W2 treatment.Therefore,W3 is the optimum moisture content,ginseng total saponins and monomer saponin content is the highest,the gene closely correlation with content of saponins and more conducive to the accumulation of ginsenosides.