Effects of temperature regulation on ginsenoside accumulation and expression of key enzyme genes / 中草药

ABSTRACT

Objective: To explore the effect of temperature regulation on the accumulation of ginsenosides and the expression of key enzyme genes in the synthetic pathway. Methods: The ginseng callus cultured for 23 d was used as the test material and placed in six incubators at 5, 10, 15, 20, 25, and 30 ℃. The dry fresh weight and saponin content were measured to determine the response sensitive temperature. GAPDH was used as the internal reference gene. Real-time PCR was used to detect nine key enzymes in the saponin synthesis pathway, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR2), Farnesyl pyrophosphate synthase (FPS), squalene synthetase (SS1), squalene epoxidase (SE1), dammarane diol synthase (DS-II), β-xanthin synthase (PNY1), β-xanthophyll C-28 hydroxylase (CYP716A52v2), protopanaxatriol synthase (CYP716A53v2), and protopanaxadiol synthase (CYP716A47). Results: 20 ℃ was the optimal temperature for the accumulation of dry and fresh weight of ginseng callus. The content of saponin in 5, 10, and 15 ℃ reached the maximum value for 2-3 d. Re, Rg1, and total saponins were 1.93, 11.93, and 1.54 times that of the control group, respectively. The expression levels of HMGR2, SS1, DS-II, SE1 and CYP716A52v2 reached their maximum values at 2-4 d of low temperature, which were 2.8, 1.6, 3.5, 3.7, and 3.8 times higher than those of the control group. Correlation analysis found that SE1 was significantly positively correlated with Re, Rg1 and total saponins. Conclusion: Moderate low temperature is conducive to the rapid accumulation of ginsenosides. SS1, DS-II, SE1, HMGR2, and CYP716A52v2 are key genes that respond to low temperatures, which play an important role in the process of ginsenoside biosynthesis against low temperatures.