Determination of Flavonoids and Carotenoids and Their Contributions to Various Colors of Rose Cultivars (Rosa spp.)

Abstract

Rose is one of the most valuable ornamental crops worldwide. In this study, the composition of hydrophilic and lipophilic pigments in petals of six rose cultivars at seven developing stages was investigated using high performance liquid chromatography and mass spectrometry. Four anthocyanins, 20 flavonols, and 10 carotenoids were detected in petals of tested cultivars. Major individual anthocyanin, flavonol, and carotenoid were cyanidin/pelargonidin 3,5-diglucoside, kaempferol 3-O-rhamnoside, and (9Z)-violaxanthin, respectively. Significant differences were observed in pigments content in petals of different rose cultivars. The yellow petals of YI and GC exhibited no to very small amounts of anthocyanins, moderate amount of total flavonols, and highest content of total carotenoids. Similarly, pink petals of PF, WQ, and YX showed average concentration of total anthocyanins, highest concentration of total flavonols, and small amount of carotenoids. Further, orange petals of CH showed highest content of total anthocyanins, lowest content of total flavonols, and average content of total carotenoids. Correlation analysis demonstrated that there were many pigments influencing petal colors. Moreover, multiple linear regression indicated that pelargonidin 3,5-diglucoside, total anthocyanins and (9Z)-violaxanthin were the major factors. In addition, this study showed that orange cultivar CH, pink cultivar PF and yellow cultivar YI can have great potential as a natural source for the extraction of pelargonidin 3-O-glucoside, kaempferol 3-O-rhamnoside, and (9Z)-violaxanthin, respectively. These investigations would contribute toward understanding the mechanism on the development of flower colors and provide a theoretical basis for the breeding of rose with specific color.

Keywords: anthocyanins; carotenoids; color; flavonols; petals; rose.

FIGURE 1

Flower phenotypes of six rose cultivars during flower development. Seven developing stages of rose flower: S1, unopened bud stage; S2, semi-opened stage; S3, fully-opened stage; S4, initial bloom stage; S5, full bloom stage; S6, bloomed stage; and S7, senescent stage. Bar = 2 cm.

FIGURE 2

High performance liquid chromatography chromatogram of (A) a mix of standard anthocyanins and (B) anthocyanins extracted from petals of Rosa ‘Chacok’ (CH) at S5.

FIGURE 3

Contents of anthocyanins (detection at 520 nm) extracted from petals of rose cultivars at different developing stages. Data represent the means of three biological replicates ± SD. Because there was no anthocyanins detected in petals of YI throughout the flower development, so the graph present only five cuntivars.

FIGURE 4

Contents of flavonols extracted from rose petals of six cultivars at different developing stages. (A) HPLC chromatograms of flavonols (detection at 350 nm): 1, kaempferol 3-O-rhamnoside-7-O-glucoside; 2, quercetin 3-O-glycoside; 3, quercetin 7-O-glucoside; 4, flavan-3-ol derivative; 5, kaempferol 3-O-rutinoside; 6, kaempferol 3-O-glucoside; 7, kaempferol 3-O-glucuronide; 8, kaempferol 3-O-(galloyl)-glucoside; 9, quercetin 7-O-rhamnoside; 10, kaempferol 3-O-xyloside; 11, kaempferol 7-O-glucoside; 12, kaempferol 3-O-arabinoside; 13, kaempferol 3-O-hexoside; 14, kaempferol 3-O-rhamnoside; 15, kaempferol 3-O-glycoside 1; 16, kaempferol 3-O-glycoside 2; 17, kaempferol 7-O-(galloyl)-glucoside; 18, kaempferol 3-O-glycoside 3; 19, kaempferol 3-(p-coumaroyl)-glucoside; 20, kaempferol. (B) A heat map of the individual flavonol contents. Row represents Z-Score normalization of the concentation of identified flavonols and column represents tested samples. Cells are colored based on concentrations in rose petals. Red represents relatively high concentration and green represents relatively low concentration of the identified flavonols in petals of each rose cultivar at seven developing stages. Each value represents the average of three biological replicates. (C) The concentration of total flavonols. Data represent the means of three biological replicates ± SD.

FIGURE 5

Contents of carotenoids extracted from rose petals of six cultivars at different developing stages. (A) HPLC chromatograms of carotenoids (detection at 450 nm): 1, (13Z) + (di-Z)-violaxanthin; 2, (all-E)-violaxanthin; 3, (13/13′Z)-antheraxanthin; 4, (all-E)-luteoxanthin; 5, (13/13′Z)-neoxanthin; 6, (9Z)-violaxanthin; 7, (all-E)-lutein; 8, (all-E)-zeaxanthin; 9, (9/9′Z)-lutein epoxide; 10, (all-E)-β-carotene. (B) A heat map of the individual carotenoid contents. Row represents Z-Score normalization of the concentation of identified carotenoids and column represents tested samples. Cells are colored based on concentrations in rose petals. Red represents relatively high concentration and green represents relatively low concentration of the identified carotenoids in petals of each rose cultivar at seven developing stages. Each value represents the average of three biological replicates. (C) The concentration of total carotenoids. Data represent the means of three biological replicates ± SD.

FIGURE 6

A heat map of correlation matrix of color parameters and 47 compounds from petals of six rose cultivars at seven developing stages. Each square indicates Pearson’s correlation coefficient for a pair of data, and the intensity of red and gree colors in the heat map indicates the level of positive and negative correlation, respectively.