Flower scent composition in Dianthus and Saponaria species (Caryophyllaceae) and its relevance for pollination biology and taxonomy

Floral fragrance compounds of seven Dianthus species (D. arenarius, D. armeria, D. barbatus, D. deltoides, D. monspessulanus, D. superbus, and D. sylvestris) and one Saponaria species (S. officinalis) (Caryophyllaceae) were studied using headspace adsorption technique followed by gas chromatography massspectrometry (GC-MS). The number of compounds (fatty acid derivatives, benzenoids, phenyl propanoids, isoprenoids, and nitrogen containing compounds) identified in the floral odors ranged from 18 to 51 but all were dominated by only 1–3 compounds. Most of the compounds identified in this study have been previously reported in floral scents from species of the closely related genus Silene L. However, the phenyl propanoids eugenol, methyleugenol, methylisoeugenol, cis-asarone, and trans-asarone have formerly not been found in Silene. Based on the measurement of Sørensen’s index of similarity (I_s) nonmetric multidimensional scaling (MDS) was used to detect meaningful underlying dimensions and to visualize similarities between the investigated species. The MDS analysis showed three groups of species, (1) the diurnal D. armeria, D. barbatus, and D. deltoides are characterized by the predominance of fatty acid derivatives, (2) the closely related nocturnal D. monspessulanus, and D. superbus by high relative amounts of isoprenoids such as cis-β-ocimene and β-caryophyllene, and (3) the species D. arenarius, D. sylvestris and S. officinalis by a predominance of benzenoids, especially methylbenzoate. The results are discussed in relation to pollination, especially by butterflies, moths, and hawkmoths.