Correlation between ginsenoside accumulation and SQS and SQE gene expression in different organs of Panax quinquefolius / 中草药

ABSTRACT

Objective: To examine the biological accumulation of total ginsenosides and their monomers, and determine their relationships with the expression of squalene synthase (SQS) and squalene epoxidase (SQE) genes that are involved in the ginsenoside biosynthetic pathway in different organs of Panax quinquefolius. Methods: Fourteen organs of four year-old P. quinquefolius were used as materials. Total ginsenosides were extracted using the Soxhlet ginsenoside extraction method, and the contents of total ginsenosides and their monomers Rg1, Re, Rb1, Rc Rb2 and Rd in the organs were determined by the Vanillin-sulfuric Colorimetry and HLPC methods, respectively. The expressions of the SQS and SQE genes in the organs were profiled by real-time quantitative PCR. Results: The biological accumulation of total ginsenosides and each of their monomers varied significantly (P<0.01) in different parts of P. quinquefolius.Except for ginsenoside monomer Rb 2, there were significantly positive correlations between total ginsenoside and monomers Re, Rg1, Rb1 and Rd (P<0.01). The expressions of both SQS and SQE genes were extremely significantly different among the 14 plant parts (P<0.01) and significantly positively correlated with the biological accumulation of total ginsenoside and monomers, Re, Rg 1, Rb1 and Rd (P<0.05). Conclusion: The results indicate that the SQS and SQE genes play the important roles in the biosynthesis of total gingenosides and their monomers.