Positive correlation between color and scent in rose petals with floral bud development

We analyzed the changes in the floral pigments and scent compounds of rose flowers during floral bud development to determine the color-scent association during synthesis. The two distinct petal-colored cultivars ‘Penny Lane’ (yellow, carotenoid type) and ‘Vital’ (red, flavonoid type) were used in this study. Floral buds were divided into five developmental stages, S1 to S5. As the floral buds developed, the petals of ‘Penny Lane’ or ‘Vital’ turned brilliant yellow or red, with increased b* and a* values, respectively. In ‘Penny Lane’, the α-carotene content did not change through the stages, but the β-carotene level was 4 times higher at S4 than at S1 and then decreased again at S5. ‘Vital’ had little cyanin at S1, but it gradually increased by 20 times until S4 and then decreased 35% at S5. The changes in most of the scent compounds in ‘Penny Lane’ and ‘Vital’ throughout floral bud development were similar to those in the pigments. In both ‘Penny Lane’ and ‘Vital’, 2-phenylethanol, 3,5-dimethoxytoluene, and methyl eugenol increased until S4 and then decreased at S5. However, the amount of geraniol in ‘Penny Lane’ showed no content change from S1 to S4, remaining at 1.1 to 1.9 μg·g^-1 FW, but it was absent at S5. Changes in the content of pigments and scent compounds occurred simultaneously with flower development, showing similar rates of increase and decrease. The petals of both ‘Penny Lane’ and ‘Vital’ got progressively more brilliant in color and more strongly scented until S4 and then grew pale with a weakening scent at S5.