## 1 Introduction  
The root of Asian ginseng (_Panax ginseng_ [PERSON]), which has been used as an important herbal medicine, has existed for thousands of years in China, Japan, and Korea [1]. The root has crucial nutritive value, is particularly cultivated in Chinese traditional culture, and the reputation of its effectiveness has reached mythic proportions [2, 3]. Modern medicine has evidenced that the most important active ingredient in _ginseng_ is ginseng, which has significant benefits for humans including anticancer [4, 5], immunomodulatory, and anti-diabetic properties [6, 7], among others. The ginsengides can be classified into two groups (dammarane-type and oleanane-type) by the structure of the aglycones. The dammarane ginensosides are the primary type of ginensosides, and they consist of protopanaxadiol (PPD)-type saponins and protopanaxatriol (PPT)-type saponins [2]. The ginsengide biosynthesis pathway of the dammarane-type has been reported by our groups [8, 9, 10]. As shown in Figure 1, the biosynthesis of ginsengide is mainly completed through three reaction steps. In the first step, isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP) are generated through several reactions, and the key enzyme is 3-hydroxy-3-methylglutaryl CoA reductase (HMGR). The above is the first stage. Farnesyl diphosphate (FPP) is produced by the catalysis of farnesyl diphosphate synthase (FPS). As a substrate, FPP generates squalene by the catalysis of squalene synthase (SS) [9]. Squalene epoxidase (SE) acts as the substrate in the formation of 2,3-oxidosqualene. The 2,3-oxidosqualene can be converted into protopanaxacid; this conversion is dependent on dammarenediol synthase (DS). Cytochrome P450 (CYP450), which is involved in modifications of the ring and side chain in terpene biochemistry, can convert protopanaxadiol to protopanaxatriol. Finally, different amounts of monosaccharides are added to the triterpene aglycones by glycosyltransferase (GT), and the procedure will lead to the generation of different ginensosides. As an important medical herb, fresh ginseng is an important economic industry in northeastern China [11; 12]. Ginensoside has substantial medicinal value, and the Chinese pharmacopeia clearly stipulates that the ginseng content must reach a certain degree before it can be used as a medicine. The roots of fresh ginseng have more malonyl ginensosides, amino acids, and polysaccharides than dried roots [13; 14]. Meanwhile, fresh ginseng may have better medicinal effects and an overall higher quality than wild ginseng or other products [13; 15]. The ginseng accumulates over time, and fresh ginseng, therefore, varies in its medicinal effects based on age [16]. [PERSON] et al. has reported the correlation of ginsenoside with the expression of key genes in ginseng with different cultivation times [17]. Figure 1: The biosynthesis pathway of dammarane ginsenoside. (AACT: acetyl-CoA C-acetyltransferase; HMGS: hydroxy methyl glutaryl-CoA synthase; IDI: isopentenyl pyrophosphate isomerase; MPD: mexolonate pyrophosphate decarboxylase; PMK: Phosphomevalonate kinase; MK: mexolonate kinase; GPS: Geranyl Pyrophosphate Synthase: \(\beta\)-AS: \(\beta\)-amyrin synthase). However, there has been no reports on the correlation between the ginsengides and key enzyme activity in the biosynthesis of ginsengides. Additionally, there have been no reports of the seven key enzymes examined in our study in the synthesis of ginsengides. We used fresh ginseng roots of different ages. In addition to systematically measuring the activity of seven key enzymes in the synthesis of ginseng saponins in fresh ginseng for the first time, we also measured the gene expression of the same seven key enzymes. We aimed to examine the relationship between the changes in the activity of these key enzymes and gene expression with the ginsengide content in ginseng of varying ages. The results showed that DS and GT enzyme activity are significantly correlated with the ginsengide content in ginseng.