# Monoterpenoids Evolution and MEP Pathway Gene Expression Profiles in Seven Table Grape Varieties
## 2 Results and Discussion
### Evolution of Monoterpenoids during Berry Development  
In 2013, for 'Moldova', \(\beta\)-_trans_-Ocimene, \(\beta\)-_cis_-Ocimene, _trans_-Rose oxide, and _cis_-Rose oxide were almost not detected during the berry development, most of the compounds decrease from veraison to maturity; 'Christmas rose' showed the similar evolution pattern (Figure 1A). And they exhibited the similar evolution pattern in the 2014 season (Figure 1B). These two varieties were categorized as neutral flavor, the C6 alcohol and aldehyde were their dominant compound according to our previous research, and the decrease trend of monoterpenoids was also consistent with the other neutral varieties of wine grapes, such as Shiraz and Cabernet Sauvignon [9]. For 'Muscat of Alexandria' and 'Italia', most of monoterpenoids accumulated from veraison to maturity, especially for the dominant compounds of Geraniol, \(\beta\)-Citronellol, _trans_-Furan linalool oxide, _cis_-Furan linalool oxide and linalool. 'Tamina' accumulated more content of neral, citronellol, \(\gamma\)-geraniol, and nerol. The content of geraniol, geraniol, geraniol, geraniol, nerol, and neral in 'Zaomeiguixiang' were quite same or even higher than 'Xiangfei'. Geranic acid showed a significant decrease near ripening in the above two varieties. Nerol oxide had similar accumulation pattern in 'Italia' and 'Muscat of Alexandria'. The concentration of linalool increased during development except for the varieties of 'Christmas Rose' and 'Moldova'; Linalool accumulated since veraison, then decreased slightly near maturity in 'Xiangfei' and 'Muscat of Alexandria'. Linalool oxide was the cyclized form of linalool, and had four kinds of isomers including _trans_/_cis_ and 'furan/pyran type, the content of linalool oxide in 'Xiangfei' were much higher than the other varieties, while _cis_-furan linalool oxide was not detected in all stages in 'Moldova' in the 2014 season. Geraniol might be transferred to citronellol by reduction reaction, then be cyclized to produce the rose oxide; Geraniol and Citronellol did not show any significant changes in these seven varieties except 'Zaomeiguixiang'; _trans_-rose oxide and _cis_-rose oxide were not detected in the all stage in 'Christmas Rose' and 'Moldova', and remained at the low level in other five varieties. These table grapes were clustered into three groups regarding the evolution similarity of monoterpenoids in both seasons (Figure 1). The two neutral grapes, 'Christmas Rose' and 'Moldova' belonged to type I, in which most of the monoterpenoids showed more or less decrease since veraison, but the total amount of monoterpenoids did not show any apparent fluctuation. 'Tamina', 'Italia' and 'Muscat of Alexandria' could be classified into type II, in which monoterpenoids increased since veraison, and the total concentration varied between 30 \(\upmu\)g/L to 140 \(\upmu\)g/L. Type III, including 'Zaomeiguixiang' and 'Xiangfei', showed a similar trend, and the total content of monoterpenoids ranged between 130 \(\upmu\)g/L to 1200 \(\upmu\)g/L. It was worth noticing that again 'Zaomeiguixiang' had higher content of citronellal, \(\gamma\)-geraniol, geraniol, neral, nerol, and geranial, while 'Xiangfei' had more abundant of neral oxide, \(\alpha\)-terpineol, 4-terpineol, _trans_-furan linalool oxide, _cis_-furan linalool oxide, but for other compounds, these two varieties had similar trend during berry development. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \multirow{2}{*}{**Compounds**} & \multicolumn{3}{c}{**Variety**} & \multicolumn{3}{c}{**Season**} & \multicolumn{3}{c}{**Variety \(\times\) Season**} \\  & **F Value** & \(p\) & **Sig. ** & **F Value** & \(p\) & **Sig. ** & **F Value** & \(p\) & **Sig.