# Exploration of Floral Volatile Organic Compounds in Six Typical _Lycoris_ taxa by GC-MS
## 2 Results
### Determination of Key VOCs  
The larger the VIP value, the more significant the difference in the variables. When the VIP value is greater than 1, the corresponding variable can be defined as the key variable of the discriminant model [27]. In the PLS-DA model established in this study, there were 14 compounds with a VIP value greater than 1--namely, \(\beta\)-ocimene, \(\beta\)-cyclocitral, 9-octadecype, undecanal, \(\beta\)-ionone, geranyl linallol, (E)-2,7-dimethyl-3-octen-5-yne, methyl benzoate, \(\alpha\)-farnesene, nonanal, benzyl benzoate, decanal, E-nerolidol, and NA2 (Table 1). The above VOCs were identified as key differential aroma components among the six different _Lycoris_ taxa. To improve the accuracy of the analysis, a Kruskal-Wallis test was applied to further analyze the VOCs with a VIP value greater than 1. We found that the 14 VOCs were all statistically significantly different (\(p<0.05\)) among the six different _Lycoris_ taxa. Therefore, after combining the results of PLS-DA and the nonparametric test analysis, 14 key differential  
Figure 3: Chemometric analysis of volatile organic compounds (VOCs) in six _Lycoris_ taxa detected by GC-MS. (**a**) Score plot and (**b**) loading plot of t equal GC-MS profiles of six _Lycoris_ taxa using a partial least squares-discriminant analysis (PLS-DA). (**c**) Clustering of the 32 VOCs detected in six _Lycoris_ taxa. VOCs coded in the loading plot were: (1) NA3; (2) \(\beta\)-myrrene; (3) eucalypt; (4) _trans_-\(\beta\)-ocimene; (5) methyl2-ethylhexanoate; (6) \(\beta\)-ocimene; (7) methyl benzoate; (8) nonanal; (9) allo-ocimene; (10) (E)-2,7-dimethyl-3-octen-5-yne; (11) benzyl nitrile; (12) benzyl acetate; (13) A-terpineol; (14) methyl salicute; (15) decanal; (16) \(\beta\)-cyclocitral; (17) 3-methoxy-5-methylphenol; (18) NA1; (19) benzenepropanoic acid, \(\alpha\)-(hydroxyimino)-; (20) undecanal; (21) benzyl isovalerate; (22) caryophyllene; (23) isoamyl benzoate; (24) _trans_-\(\beta\)-farnesene; (25) \(\beta\)-ionone; (26) benzyl tiglate; (27) \(\alpha\)-farnesene; (28) E-nerolidol; (29) NA2; (30) 9-octadecype; (31) benzyl benzoate; and (32) geranyl linallol. The compounds in black frames are the 14 key VOCs. White indicates low expression and red indicates high expression.  
components in the six different _Lycoris_ taxa were identified. In addition, the 14 key VOCs had a certain regularity in the distribution within the six _Lycoris_ taxa (Figure 3c, in black frames). \(\beta\)-Ocimene, (E)-2,7-dimethyl-3-octen-5-yne, undecanal, decanal, nonanal, \(\beta\)-ionone, and \(\alpha\)-farnesene had the highest contents in _L. aureus_. These floral VOCs are mainly aldehydes and terpenoids, and the aromas of these compounds are generally citrus and floral notes. Methyl benzoate, E-nerolidol, and benzyl benzoate were higher in _L. sprengeri_, and these compounds typically have floral, fruity, and woody notes.  
_L. longituba_ contained the highest content of methyl benzoate, which typically has wintergreen and cananga notes. This is consistent with the sensory evaluation results of _L. longituba_, indicating that this compound may play an important role in the formation of the aroma of _L. longituba_. 9-Octadecyne and geranyl linalll were only detected in _L. longituba_ var. _flava. L. longituba_ var. _flava_ also contained \(\beta\)-ocimene and E-nerolidol; these compounds have a floral, citrus, and woody aroma. Compared to the other taxa, _L. chinensis_ and _L. radiata_ were essentially unscented, with the corresponding lack of aroma components. It is hypothesized that the different VOC contents in different _Lycoris_ taxa have an important influence on the aroma of the corresponding _Lycoris_ taxa.