Floral pigment-scent associations in eight cut rose cultivars with various petal colors

The associations between petal pigments and scent compounds of Rosa hybrida were determined in eight commercial cultivars with different petal-colors, visually classified as four petal-color groups: ‘Beast’ and 'Marilyn Monroe' in white (W), ‘Good Time’ and ‘Penny Lane’ in yellow (Y), ‘Ahoi’ and ‘Pink Condor’ in pink (P), and ‘Pearl Red’ and ‘Vital’ in red (R). The petal pigments were distinct by visual petal color polymorphs. Yellow petals contained only carotenoids and unusually large amounts of β-carotenes as their primary pigments, whereas white ones included minimal levels of carotenoids. As expected, pink and red flowers had cyanin as the major anthocyanin. The amount of cyanin in petals was significantly higher in the red petals. Unlike petal pigments, the scents were abundant in white and yellow flowers, containing both phenolic and terpene compounds. The pink and red flowers, on the other hand, were scented with only phenolics as represented by 2-phenylethanol and 3,5-dimethoxytoluene, which existed in all eight cultivars. The amount of detected scent was up to six times higher in the white or yellow flowers than in the pink or red ones. A principal component analysis (PCA) with all detected pigments and scents resulted in classifying eight cultivars as three independent groups: (GI) ‘Beast’, (GII) ‘Good Time’, ‘Penny Lane’, and ‘Marilyn Monroe’, and (GIII) ‘Ahoi’, ‘Pink Condor’, ‘Pearl Red’, and ‘Vital’. ‘Marilyn Monroe’ (W) belonged to GII with yellow cultivars, not to GI with ‘Beast’ (W). The PCA coordinates of pink and red cultivars were so close that they belonged to the same group, GIII. With this information, we know that rose petal colors may differ in terms of their pigment and scent profiles.