## 3 Discussion  
In this study, the types and contents of saponin components had tissue specificity in the below and above ground tissues of _P. notoginseng_. Protopanaxadiol- and protopanaxatriol-type saponin contents were higher in the below ground tissues than in the above ground tissues, especially in the rhizome. The transcripts were different in the below ground and above ground tissues of _P. notoginseng_. A total of 482 and 882 unigenes were shared in the below ground and above ground tissues, respectively. A total of 38 and 37 CYP transcripts (RPKM \(\geq\) 10) were highly expressed in the below ground and above ground tissues, respectively. The expression level of CYP716A47 was high in the above ground tissues, especially in the flower, and the relative expression of CYP716A53v2 was high in the below ground tissues, especially in the rhizome. The contents of most saponin were remarkably related to the expression levels of CYP716A47 and CYP716A53v2, suggesting that the different expression of CYP716A subfamily genes (CYP716A47 and CYP716A53v2) resulted the specific saponin distribution in the different tissues of _P. notogonseng_. Ginsenosides have uneven distribution and accumulation in _Panax_ plants [8; 24]. The levels of ginseng in berries are higher than those in _P. ginseng_ roots [25]. The total ginseng contents in _P. quinquefolius_ leaves are higher than those in its roots [26]. In our studies, the contents of saponins were higher in the below ground tissues than in the above ground tissues, especially in the rhizome, and these findings were similar to previous studies [27]. The rhizome is an important part of perennial plants, such as _P. notoginseng_, because it possesses the buds for sprouting in the succeeding year. The abundant accumulation of various saponins in the rhizome can play a defensive role against pathogens and insects. In addition, the contents of protopanaxadiol- (Rb1 and Rd) and protopanaxatriol-type (R1, Rg1, and Re) saponins were higher in the below ground tissues than those in the above ground tissues, whereas protopanaxadiol-type saponins (Rb2 and Rc) were detected in the above ground tissues only. These results were similar to those in previous studies [15; 28]. Therefore, saponin types and contents had an uneven distribution in different tissues of _P. notoginseng_. The transcripts in the below ground and above ground tissues of _P. notoginseng_ differed. A total of 1351; 1724; 2042; 4668; 5206; and 12,038 unigenes were specifically expressed in the stem, rhizome, leaf, root, flower, and fibril, respectively, suggesting that the transcripts in the six tissues were differentially expressed. This observation was similar to previous findings [29]. These annotations and transcript differences provided useful information for investigating the functions and expression patterns of unigenes in _P. notoginseng_. A majority of the sequences involved in the carbohydrate metabolic processes were identified in _P. ginseng_[30]. In our data, 55,205 sequences were assigned to the metabolic pathways, and 2128 sequences were annotated to the metabolism of terpenoids \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline
**Genes** & **NG-R1** & **G-Rg1** & **G-Re** & **G-Rb1** & **G-Re** & **G-Rb2** & **G-Rd** & **PTS** & **PDS** & **Total Saponins** \\ \hline CYP716A47 & \(-\)0.056 & \(-\)0.368 & \(-\)0.316 & \(-\)0.153 & 0.580 * & 0.707 * & \(-\)0.217 & \(-\)0.338 & 0.334 & \(-\)0.103 \\ CYP716A53v2 & 0.956 ** & 0.991 ** & 0.999 ** & 0.918 ** & \(-\)0.579 * & \(-\)0.596 ** & 0.926 ** & 0.994 ** & 0.454 & 0.921 ** \\ \hline \end{tabular}
* Correlation is significant at the 0.05 level (2-tailed); ** Correlation is significant at the 0.01 level (2-tailed).  
\end{table} 
Table 2: Correlation analysis between the expression of two CYP genes and saponins contents. and polyketides. Unigene expression has tissue-specific distribution in the roots, stems, leaves, and flowers of _P. ginseng_, and this finding was similar to our results [31].