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Valentina Schmitzer, Maja Mikulic-Petkovsek, Franci Stampar, and Vlasta Cunja

Detailed anthocyanin and flavonol profiles were investigated in three flower segments of four different hybrid primrose (Primula ×polyantha) cultivars, and individual compounds were identified using high-performance liquid chromatography (HPLC)/mass spectrometry system. Chlorophyll a and b and total carotenoids were evaluated spectrophotometrically in the corolla tube (CT), and distal and proximal flower segments, and the color of each segment was assessed with a colorimeter. Chlorophyll b predominated over chlorophyll a in all flower segments, and the highest total chlorophyll levels were found in the CTs. Sixteen different anthocyanins (glycosides of cyanidin, delphinidin, peonidin, petunidin, malvidin, and rosinidin) were identified in red, pink, and blue flower extracts. Distal segments of the red hybrid and proximal segments of the pink hybrid accumulated highest levels of total anthocyanins, and no red pigments were detected in yellow-flowered hybrid primrose. Six groups of flavonols (40 individual compounds in total) were detected in different flower segments of four hybrid primrose cultivars. Yellow primrose was characterized by the greatest diversity of flavonols as it contained four isorhamnetin, five kaempferol, six laricitrin, three myricetin, six quercetin, and six syringetin glycosides. On the other hand, the smallest variety of flavonols was detected in pink hybrids. Total phenolic content (TPC) was lowest in the CT (yellow > red > pink), significantly higher in the proximal flower segment (yellow > red > pink), and highest in the distal part of the primrose petal (yellow > pink > red).

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Vlasta Cunja, Maja Mikulic-Petkovsek, Franci Stampar, and Valentina Schmitzer

Using high-performance liquid chromatography/mass spectrometry, leaf and petal phenolic profiles of four rose (Rosa) species (R. canina, R. glauca, R. rubiginosa, R. sempervirens) traditionally used for medicinal purposes and three modern rose cultivars (Rosarium Uetersen, Ulrich Brunner Fils, Schwanensee) were determined. An abundance of phenolic constituents was identified: seven different anthocyanins and 31 flavonols in petals; 30 flavonols, 14 phenolic acids, and their derivatives; 15 flavanols; and 20 hydrolysable tannins in leaves. Additionally, petal color was measured with a colorimeter and regression analysis indicated a strong correlation between color parameter a* and total anthocyanin content. The content and composition of phenolic compounds varied significantly among species and cultivars and plant organs investigated. Distinct differences in the distribution of leaf phenolic compounds were observed, especially between Rosa species and modern rose cultivars. In general, leaves of analyzed species were richer in content of most phenolic groups and individual components compared with cultivars. Multivariate statistical analysis clustered the investigated species and cultivars into three distinct groups. Among species, leaves of R. canina stood out with their high and varied phenolic content. Conversely, leaves of the susceptible cultivar Schwanensee appeared most dissimilar as a result of their low levels of phenolic constituents.

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Gregor Osterc, Maja Mikulic Petkovsek, Franci Stampar, Biljana Kiprovski, Blanka Ravnjak, and Joze Bavcon

Common cyclamen (Cyclamen pururascens Mill.) is a very interesting species not only for various breeding programs but also as an ornamental plant. The plants possess interesting floral and foliage characteristics, nice fragrances, and a very useful flavonol profile. The last is very important from the point of view of protecting against diseases and physiological disorders. Twenty-two different genotypes originating from different regions in Slovenia were analyzed in detail, based on their floral and foliage characteristics. Anthocyanin and flavonol contents were determined using high-performance liquid chromatography (HPLC)-photodiode array-mass spectrometry (MS). Color characteristics were colorimetrically evaluated separately for petals and leaves. In terms of color measurements, significant differences among the sites of origin were shown with parameters a* and L* when petals were analyzed, and with parameter a* when leaves were analyzed. The pH of petal sap stayed within the acid range, ranging from 3.96 to 4.82. Five different anthocyanins (malvidin-3,5-diglucoside, cyanidin-3-neohesperidoside, delphinidin-3-glucoside, delphinidin-3,5-diglucoside, and delphinidine-3-rutinoside) were analyzed in flowers, and this is the first report of delphinidin metabolites naturally present in common cyclamen genotypes. In relation to plant leaves, malvidin-3,5-diglucoside, malvidin-3-rutinoside, malvidin-3-glucoside, cyanidin-3-neohesperidoside, and peonidin-3-neohesperidoside were measured. Fifteen different flavonols were determined in common cyclamen flowers and 10 different flavonols in common cyclamen leaves. Various glycosides of quercetin, myricetin, and kaempferol were analyzed, as well as isorhamnetin-3-rutinoside, laricitin-3-rutinoside, and neohesperidin. The floral and foliage characteristics of the genotypes (physical and chemical) were mainly affected by the environmental conditions of the locality of origin of the genotypes (annual disposition of temperature and precipitation, structure of the soil, etc.).

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Jan Bizjak, Nika Weber, Maja Mikulic-Petkovsek, Ana Slatnar, Franci Stampar, Zobayer Alam, Karl Stich, Heidi Halbwirth, and Robert Veberic

The influence of two foliar applications of Phostrade Ca, which contains high concentrations of phosphorus and minor amounts of calcium and nitrogen, on color development and selected primary and secondary metabolites was investigated during advanced maturation of ‘Braeburn’ apple. Changes of hydroxycinnamic acids, flavanols, dihydrochalcones, flavonols, and anthocyanins were monitored six times during the advanced ripening until technological maturity of the fruits. Additionally, the changes in the chromatic values a*, h°, and the lightness coefficient L* were recorded weekly. The colorimetric parameters showed a significant difference in the intensity of red coloration between the treated and untreated apples. Spraying with Phostrade Ca also resulted in a significant increase in most individual sugars, total sugars, and concentration of anthocyanins and flavonols. Moreover, the amount of phosphorus (P) in the treated leaves was increased. However, the total phenolic content and accumulation of other classes of flavonoids such as hydroxycinnamic acids, flavonols, and dihydrochalcones were not influenced. Phostrade Ca treatment significantly increased dihydroflavonol 4-reductase (DFR) and slightly flavanone-3-hydroxylase (FHT) activity, which were correlated with anthocyanin synthesis but had no effect on phenylalanine ammonia lyase (PAL) and chalcone synthase/chalcone isomerase (CHS/CHI) activity. The results indicate that two foliar applications of Phostrade Ca late in the growing season represent an effective way to improve the color of ‘Braeburn’ apples at commercial harvest.