## 3 Discussion
xiphioides_ present, nevertheless, a slight difference in the intensities of certain compounds, which can affect the floral odor and lead to a difference in odor for the two forms of this species [11]. Found mainly in the flowers of both forms of _T. crocata_, phenylpropanoids represent the second class of VOCs emitted by plants. The first molecule of the phenylpropanoid pathway is phenylalanine, which is derived from the shikimate biosynthetic pathway. The deamination of this molecule by phenylalanine ammonia-lyase (PAL) forms the phenylpropanoid skeleton producing trans-cinnamic acid. All phenylpropanoid compounds are derived from trans-cinnamic acid by a succession of hydroxylation, methylation, and reduction steps [21]. Among the phenylpropanoids identified in this study, benzylacetate and phenylethyl acetate were found mainly in the floral emissions of yellow _crocata_. Benzyl acetate is a compound with a pleasant odor and is commonly found in plants such as jasmine, hyacinth, gardenia, and azalea, and is thought to be formed from the oxidation of cinnamoyl CoA [7,8,22]. Phenylethyl acetate is widely used in the cosmetic, food, and pharmaceutical industries for its pleasant rose smell. It is present in rose essential oils and is the main aromatic volatile ester emitted by rose flowers. Traditionally, this compound is obtained by acetylation of phenylethyl alcohol; moreover, the acetylation of aromatic alcohols catalyzed by alcohol acetyltransferase leads to volatile acetate esters in plants [23,24]. Other phenylpropanoids, such as eugenol, methyl eugenol, benzyl benzoate, phenethyl benzoate, and benzyl salicate, were very present in the floral emissions of orange _crocata_. In the phenylpropanoid biosynthetic pathway, eugenol and isoeigenenol are obtained from coniferyl acetate through eugenol synthase and isoeigenenol synthase. Subsequently, a methylation reaction of eugenol, catalyzed by an \(O\)-methyltransferasease, allows us to obtain methyl eugenol [21]. Eugenol and methyl eugenol are major constituents of several essential oils, such as clove, basil, cinnamon, lavelender, and jasmine essential oils. Eugenol is widely used in perfumery due to its powerful spicy odor, and methyl eugenol is widely used as a flavoring agent in food products [25; 26; 27]. In plants such as _Clarkia breweri_ and _Petunia hybrida_, benzyl benzoate and phenethyl benzoate are obtained from benzyl alcohol and phenylethanol, respectively, through benzoyl-CoA: benzyl alcohol/phenylethanol benzoyltransferase [28; 29]. In addition to its activity in the treatment of scabies and lice, benzyl benzoate is used as a fixative in perfumery [26]. Benzyl salicate is the benzyl ester of salicylic acid, it is widely used in the cosme industry and is used in the composition of many perfumes [30]. Volatile aromatic esters generally contribute to a sweet fruity smell [31]. These results show that there is a slight difference in the floral volatile profiles of the two forms of _T. crocata_, especially in the intensities of some volatile compounds. This difference could be associated with the difference in floral colors of the two forms of this species. Indeed, it was shown that plants of the same species having a variation of floral color also presented a variation in the composition of floral volatiles. For example, a study on orchids showed that the color morphs of \(O\). _simia_ presented different volatile profiles; the white flowers emitted more benzenoid compounds and lipid products than the purple flowers [32]. However, there are studies that did not find a clear difference in the odor chemistry of color morphs of the same species [33; 34]. Thus, even if the slight difference in volatile profiles of yellow and orange _crocata_ flowers could be associated with the difference in flower colors, it could also be due to natural selection by pollinators or mutations in genetic drift or metabolic pathways. In _T.