# Exploration of Floral Volatile Organic Compounds in Six Typical _Lycoris_ taxa by GC-MS
## 1 Introduction  
_Lycoris_ Herb. (Amaryllidaee) contains approximately 20 species that are primarily located in Asia [1], with 15 species distributed in China [2]. Studies have been conducted on the medicinal properties [3; 4; 5; 6], molecular cloning [7], karyotype [8], and evolutionary biology [9] of these _Lycoris_ species. Due to the particular shapes and various colors of the petals, _Lycoris_ is an important ornamental flower in the summer [10].  
Floral scents are secondary metabolites released by flowers and are mainly composed of many low molecular weight volatile compounds, including terpen, benzenoid aromatics, and fatty acid derivatives [11]. Floral aroma is an important trait within ornamental plants and is also a critical factorin evolution because these olfactory signals (i.e., floral volatile organic compounds (VOCs)) attract pollinators [12; 13]. For example, in _Chiloglottis_ orchids, the presence of specific volatile 'chiloglottones' attracts specialist pollinators, which may lead to reproductive isolation and affect evolution [14]. In addition, the VOCs in flowers serve multiple biological functions, such as defense against pests, herbivores, and colonizing microorganisms [15; 16], which are generally correlated with the evolution of floral scents [17]. Recently, many _Lycoris_ taxa with excellent and special fragrances were identified in our _Lycoris_ germplasm resource nursery [18]. For example, the aromas of _L. longituba_ and _L. longituba_ var. _flava_ have wintergreen and lily notes, while _L. aureus_ has a citrus aroma. Some _Lycoris_ species are represented by many particular scents; however, few scientific studies have been conducted on the different volatile compounds that _Lycoris_ flowers produce and emit, or the variation of volatile compounds emitted from _Lycoris_ species.  
Headspace solid-phase microextraction (HS-SPME) can be used to extract components via the selective adsorption characteristics of the extracted fibers, and this method can be used to collect VOCs from flowers. For example, HS-SPME was used to collect the different categories of compounds released by different _Freesia_ taxa [19]. Another study examined different solid-phase microextraction (SPME) conditions for achieving the optimum collection methods of floral volatiles from _Echinacea_[20]. Recently, partial least squares-discriminate analysis (PLS-DA) has been applied to identify VOCs and evaluate their quality in many plant species. In a previous study based on VOCs profiles, seven different cultivars of _Polianthes tuberose_ could be distinguished from each other and four distinct clusters were obtained by PLS-DA [21]. Briefly, many different plant taxa could be distinguished by PLS-DA [22; 23; 24]. Moreover, PLS-DA could also reveal the core differential VOCs, such as in 42 different apple varieties [25]. Meanwhile, the variable importance in projection (VIP), one of the variable importance factors of PLS-DA, has been widely used in different fields and was previously shown to be effective for raw total ion GC-MS chromatogram data [26; 27].  
Six _Lycoris_ taxa with different, yet common among the genus, flower colors and shapes were sampled in this study. HS-SPME-GC-MS and PLS-DA were used to analyze, quantify, and characterize the floral VOCs emitted from different _Lycoris_ taxa. To the best of our knowledge, this is the first comparison of floral VOCs in different _Lycoris_ taxa.