# Comparative Analysis of Volatile Compounds in Flowers of Different _Actinidia_ Species
## 2 Results and Discussion
### Diversity of Volatile Compounds in Flowers of Different A. arguta Genoptypes
The same combination of stereoisomers was found in two out of 15 species investigated (_Cyanchum auriculatum_ and _Viburnum oulus_). Some species contained one stereoisomer of linalool and the same (_Syringa vulgaris_) or similar (e.g., _Silene otites_, _Prunus padus_ and _Daplune cheorum_) combination of lilac alcohol and aldehyde stereoisomers. Further analysis revealed that derivatives of linalool were more complex than expected. In earlier research of _A. arguta_, these derivatives were present only in a few examined genotypes, and some of these were found in solvent extracts [23; 25]. When investigating the stereoisomers of lilac aldehyde, it appears that our results differ from those by [PERSON] et al. [23], where only one headspace male flower sample missed one lilac aldehyde stereoisomer, whereas in this particular study only lilac aldehydes C and D were found. However, as observed earlier, the problem could be due to an inappropriate distinction of lilac stereoisomers. In a previous study, four stereoisomers of lilac alcohol were also found in headspace samples [23], while only two forms were found in our analysis. A comparison to the insightful research undertaken by [PERSON] et al. [23] shows that lilac compounds, which were first isolated from _Syringa vulgaris_ flower oil and detected in at least nine plant families [16], are important components of _A. arguta_ headspace samples. In our analysis, however, the relative content of both lilac alcohol and aldehyde was higher than in [PERSON] et al. 's [23] analysis. The reason may be methodological (that is, the use of a different method of collecting samples) as well as genetical. 5-Hepten-2-one and 6-methyl were also detected by [PERSON] et al. [23] in all headspace and solvent samples, but the content amounted to less than 1% in all genotypes. Ocimene derivatives constitute another important group among terpen. In this work, E-beta ocimene was identified in most samples, and its relatively highest content (7.0%) was found in 'Haya Kume'. Geranylacetone (found, e.g., in _Nelumbo nucifera_ oil) was present in all clones and 5-Hepten-2-one, 6-methyl- (a component of volatile oils of citronella, lemon-grass and palmarosoa oil) in most (e.g., 4.9% for 'Rubi'). 5-Hepten-2-one and 6-methyl were also detected by [PERSON] et al. [23] in all headspace and solvent samples, but the content amounted to less than 1% in all genotypes. Other terpen identified in this analysis were previously found only in single samples. However, alpha-Farnesene, detected here in the headspace, was earlier found only in the solvent extract of one female genotype. Only few benzoid compounds were identified in the headspace samples. One was the already mentioned phenylethyl alcohol. The highest content was noticed in 'Joker' (12.2%), but it stood below 5% in most of the clones. Two benzoid compounds (e.g., 2-(4-Methoxyphenyl!) ethanol) were found in six out of seven male clones, but their content was low (\(<\) 0.5%). Benzeneacetaldehyde, which is an aromative compound, was identified in four clones, but its content was low as well (\(<\) 1%). The results of [PERSON] et al. [23] suggest that benzoid compounds are not common in the headspace, but high amounts are present in solvent samples (up to 30.1%). The only compound, identified by them in larger amounts in volatile samples, was phenylethyl alcohol (6.25 and 17.2%). That was confirmed in our research. 2-(4-Methoxyphenyl!) ethanol was also identified by [PERSON] et al. [23], yet only in solvent extracts. It was found there in small amounts but in almost all samples. Nor was benzeneacetaldehyde found in previous studies, but benzaldehyde and benzene (the compounds that were not found in our genotypes) were detected in several samples. This suggests that among benzoid compounds only phenylethyl alcohol is specific to _A. arguta_, in male and female genotypes alike. The identification of other compounds may depend on their concentration in the headspace, detection possibilities, genotype or environmental impact.