# Exploration of Floral Volatile Organic Compounds in Six Typical _Lycoris_ taxa by GC-MS
## 3 Discussion  
Floral scent is a desirable feature for ornamental plants; previous studies have determined the scent compounds and patterns of release for several ornamental species such as _Lilium_[29], _Jasminum sambac_[30], and _Osmanthus fragrans_[31]. There are many factors affecting the type and content of floral fragrance, but it mainly depends on the genetic characteristics of the taxa. A study on the floral scents in eight lily taxa demonstrated that the floral VOCs emitted from scented and non-scented flowers were qualitatively and quantitatively distinct [32]. Moreover, the floral VOCs released by different _Narcissus pseudonarcissus_ varieties also had qualitative and quantitative differences [33]. Recently, the regulation mechanism of aroma biosynthesis has been well clarified by genomic, transcriptomic, and proteomic investigations, such as in _O. fragrans_[31], _Lilium_[34], and _Climonantthus praecox_[35]. Although the fragrance of _Lycoris_ is valued, previous studies have mainly focused on its medicinal value and properties, especially of its bulb [36; 37; 38]. This study is the first to compare the differences in floral VOCs between different _Lycoris_ taxa, including scented and unscented taxa (Table 2). Our results confirmed that the constituents and relative composition of floral VOCs were different by comparing six _Lycoris_ taxa (Figure 3c). The results may not only provide insight into the floral metabolic networking in _Lycoris_, but also provide valuable information for the ornamental breeding of _Lycoris_ for its scent. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**NO.** & **Compounds** & **VIP\({}^{*}\)** & _P Value_ & **Aroma Characteristics** \\ \hline
1 & \(\beta\)-ocimene & 1.32 & 0.000 & citrus, floral, woody \\
2 & \(\beta\)-cyclocitral & 1.31 & 0.006 & saffron, rose, tobacco, fruity \\
3 & NA2 & 1.31 & 0.000 & - \\
4 & 9-octadecyne & 1.3 & 0.000 & - \\
5 & undecanal & 1.28 & 0.001 & soapy, floral, citrus \\
6 & (E)-2,7-dimethyl-3-octen-5-yne & 1.27 & 0.000 & - \\
7 & \(\beta\)-ionone & 1.15 & 0.000 & woody, berry, floral, fruity \\
8 & geranyl linalll & 1.15 & 0.000 & rose \\
9 & methyl benzoate & 1.12 & 0.001 & wintergreen, cananga \\
10 & \(\alpha\)-farnesene & 1.12 & 0.000 & citrus, laverder, neroli \\
11 & nonanal & 1.06 & 0.000 & rose, orris, citrus \\
12 & benzyl benzoate & 1.04 & 0.000 & balsam, fruity \\
13 & decanal & 1.01 & 0.001 & citrus, floral \\
14 & E-nerolidol & 1 & 0.000 & floral, citrus, woody \\ \hline \hline \end{tabular} \({}^{*}\) VIP: variable importance in projection.  
\end{table} 
Table 1: Characteristics of the 14 key VOCs in the PLS-DA model. Floral scent is determined by a broad range of compounds and their complex mixture. The majority of floral VOCs are terpenoids or benzenoids, but alcohols, ketones, fatty acids, and esters may also be present. It has been demonstrated that different floral compounds could attract different pollinators. In addition, the circadian emission patterns of plant VOCs are associated with pollinators. For example, _Narcissus_ flowers were found to produce fewer VOCs at night than during the day [39], whereas _Nicotiana_ show the opposite trend due to pollinator-mediated selection [40]. Differences in floral VOC variation are influenced by special pollinators and shared evolutionary history. In this study, the floral VOCs of six _Lycoris_ taxa had significant differences, and they could be effectively distinguished by PLS-DA (Figure 3a). Among the six _Lycoris_ taxa, _L. longituba_ and _L. longituba_ var. _fava_ clustered close together, which is logical because these taxa are closely related based on karyotype information and phylogenetic relationships [41; 42]. Interestingly, in the other four _Lycoris_ taxa, _L. chinensis_ and _L. radiata_ clustered close together, whereas _L. sprengeri_ and _L. aureus_ could be discriminated from one another (Figure 3a). However, a phylogenetic study showed that _L. chinensis_ and _L. aureus_ were clustered in the same group with _L. longituba_ and _L. longituba_ var.