## 3 Discussion  
There is considerable interest in chemical composition variation in _Valeriana_ owing to the numerous beneficial properties attributed to consumption of the genus. Previously, the genes involved in volatile terpenoid biosynthesis had not been investigated in different organs of _V. fauriei_. Our study documents the compositional diversity and amount of volatile compounds, including valerenic acid and its derivatives, and quantifies the expression of genes involved in terpenoid biosynthetic pathways, in different organs of _V. fauriei_. Roots had high amounts of volatile compounds but low transcript levels. Evidently, expression levels of terpenoid biosynthetic genes did not correspond with the storage of volatile constituents, indicating that products synthesized in the stem or other organs may be translocated into the root. Earlier experimental studies have found similar results. Plants often transport natural products from a synthesis site to an accumulation site [21]. For example, compounds were synthesized in the stem and leaf, then transported to the root of _Astragalus membranaceus_ [PERSON] [22]. In addition, [PERSON] and [PERSON] [23] have reported the synthesis and translocation of glucosinolates from leaves to seeds during development in _Tropaeolum majus_ L. Moreover, nicotine and caffeine, which are primarily produced roots, are transferred to leaves in _Arabidopsis thaliana_ ([PERSON] [PERSON]. [24]. Translocation of secondary metabolites from source cells to neighboring cells, or even further to other tissues usually occurs in plants. Volatile terpen are emitted by the transcript levels of biosynthetic enzymes, and transporter for their emission is not required. However, the strong evidence which demonstrates to deny the presence of broad-specificity transporters for the emission of volatiles has not yet been identified. In addition, the mechanism for the long-distance translocation of volatiles has not been investigated in plants [25]. Therefore, we should carry out more experiments such as feeding of radio labels to _V. fauriei_ tissues to clarify the transport and accumulation of volatile compounds in further study. Various taxa of _Valeriana_, including _V. officialis_ [PERSON], _V. jatamanasi_ [PERSON], _V. officialis_ var. _latifolia_ [PERSON], _V. amurensis_ P. [PERSON]. ex Kom., _V. fauriei_, and _V. alternifolia_ Bunge var. _stolonifera_ [PERSON]. [PERSON], have been the focus of scientific studies [18; 26; 27]. Several studies have included experiments to isolate and identify chemical constituents including sesquiterpenoids and iridoid glycosides from _V. fauriei_[26; 27]. In our study, we identified 128 volatile compounds in _V. fauriei_ by GC/MS. Although most volatile compounds had high concentrations in the roots, each organ had several distinctive compounds that served as biochemical markers. For example, isovalerenic acid, which causes the malodorous characteristic, was accumulated solely in the root of _V. fauriei_. In addition, we found that borneol and bornyl acetate were the most abundant monoterenes in the roots of _V. fauriei_, in agreement with the results from previous studies. [PERSON] _et al._[18] documented that _V. officialis_ var. _latifolia_ contained the highest amounts of bornyl acetate (23.93%) in the roots. To date, \begin{table}
\begin{tabular}{c c} \hline \hline
**Compound** & **Dry Weight (ug/g)** \\ \hline valerenic acid & 69.450 \(\pm\) 0.263 \\ acetoxyvalerenic acid & 32.234 \(\pm\) 0.961 \\ hydroxyvalerenic acid & n.d. 1 \\ \hline \hline \end{tabular} Numbers indicate the mean of three replicates \(\pm\) standard deviation. 1 n.d. = not detected.  
\end{table} 
Table 2: Amounts of valerenic acid and its derivatives in _V. fauriei_ roots. more than 100 members of TPSs have been identified from various plant species [13]. The action of these enzymatic family lead to structurally diverse cyclic and acyclic monoterpenes and sesquiterpenes [28].