# Exploration of Floral Volatile Organic Compounds in Six Typical _Lycoris_ taxa by GC-MS
## 3 Discussion
_fava_, and _L. sprengeri_ and _L. radiata_ were clustered in another group [43], which is inconsistent with the PLS-DA and HCA results (Figure 3). This may be because, in addition to scent, other floral traits such as color can also affect pollinator behavior, thereby affecting reproductive isolation, leading to evolution. Studies conducted on _Petunia axillaris_ and _P. exserta_, two sister species, showed that _P. axillaris_ is white and scented, whereas the red flowers of _P. exserta_ lack scent [44]. Similarly, in the six _Lycoris_ taxa, the flowers of _L. longituba_ are white and heavily scented, while _L. radiata_ is bright red and unscented. Moreover, the flower size, flower shape, and pollen of the six _Lycoris_ taxa are also different from each other (Table 2). Differences in floral traits, such as petal color, scent, or shape, can all lead to different interactions with pollinators. _Lycoris_ flowers are diverse in color and shape, which may also affect the evolution of _Lycoris_. Some evidence showed that \(\beta\)-ocimene may function as a general pollinator attractant [45]. The phenomenon of emitting \(\beta\)-ocimene from flowers is widely distributed and the trait has been gained and lost several times across the phylogeny of flowering plants [46]. \(\beta\)-Ocimene was verified as the most important aroma compound of the six _Lycoris_ taxa. Furthermore, a comparison of the floral aroma during the tepal development of _L. longituba_ indicated that _trans_-\(\beta\)-ocimene was also the most important aroma compound [18]. \(\beta\)-Ocimene is one of the most common floral VOCs [46], and it is also a major component of the floral aroma of many species [35; 47; 48]. This study detected \(\beta\)-ocimene and its trans isomer, _trans_-\(\beta\)-ocimene, which had a high relative content in _L. longituba_, _L. longituba_ var. _fava_, _L. chinensis_, and _L. aureus_; these compounds were not detected in _L. sprengeri_ and _L. radiate_ (Table S1). This finding is consistent with the phylogenetic analysis, wherein _L. longituba_, _L. longituba_ var. _fava_, _L. chinensis_, and _L. aureus_ were in one clade, while _L. sprengeri_ and _L. radiate_ formed another clade [43]. This suggested that \(\beta\)-ocimene may be related to the evolutionary relationships among _Lycoris_ species. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Parameters** & _L. sprengeri_ & _L. longituba_ & _L. longituba_ & _L. aureus_ & _L. chinensis_ & _L. radiate_ \\ \hline Flower & & & & & & \\ \hline Color & Purple & White & Light yellow & Yellow & Yellow & Red \\ Height (cm) & \(13.56\pm 0.63^{\mathrm{c}}\) & \(16.02\pm 0.87^{\mathrm{d}}\) & \(16.24\pm 0.86^{\mathrm{de}}\) & \(10.88\pm 1.07^{\mathrm{b}}\) & \(17.78\pm 1.14^{\mathrm{e}}\) & \(5.55\pm 0.60^{\mathrm{a}}\) \\ Breadth (cm) & \(10.29\pm 0.76^{\mathrm{b}}\) & \(13.59\pm 0.81^{\mathrm{cd}}\) & \(14.77\pm 0.96^{\mathrm{d}}\) & \(10.31\pm 0.54^{\mathrm{b}}\) & \(13.01\pm 0.54^{\mathrm{c}}\) & \(8.48\pm 0.59^{\mathrm{a}}\) \\ Aroma level & Scented & Scented & Scented & Scented & Non-scented & Non-scented \\ \hline \hline \end{tabular} Note: All values are the mean \(\pm\) s.d. of four replicates. Values having same letters do not vary significantly at \(p<0.05\).  
\end{table} 
Table 2: Flower characteristics of six typical _Lycoris_ taxa from a natural population. Some plant VOCs that have antibacterial and antifungal properties can develop inhibitory effects against microbial pathogens [49; 50]. In a previous study, the VOCs of conifers were found to have an inhibitory effect on the growth of airborne microorganisms [51]. By analyzing the effects of the VOCs of five conifer species that inhibit microbes, it was found that limonene, \(\beta\)-pinene, pelargon aldehyde, decanal, and benzaldehyde could significantly inhibit bacterial growth. Terpenoids have pronounced roles in antimicrobial activities [52].