Article pubs.acs.org/JAFC
Intraspecific Variation in Carotenoids of Brassica oleracea var. sabellica Vera Mageney,† Susanne Baldermann,‡,§ and Dirk C. Albach*,† †
Institute of Biology and Environmental Sciences, Carl von Ossietzky University, Oldenburg Carl von Ossietzky Str. 9-11, 26129 Oldenburg, Germany ‡ Leibniz-Institute of Vegetables and Ornamental Crops Grossbeeren/Erfurt e. V., Theodor-Echtermeyer-Weg 1, 14979 Grossbeeren, Germany § Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany S Supporting Information *
ABSTRACT: Carotenoids are best known as a source of natural antioxidants. Physiologically, carotenoids are part of the photoprotection in plants as they act as scavengers of reactive oxygen species (ROS). An important source of carotenoids in European food is Brassica oleracea. Focusing on the most abundant carotenoids, we estimated the contents of ß-carotene, (9Z)neoxanthin, zeaxanthin, and lutein as well as those of chlorophylls a and b to assess their variability in Brassica oleracea var. sabellica. Our analyses included more than 30 cultivars categorized in five distinct sets grouped according to morphological characteristics or geographical origin. Our results demonstrated specific carotenoid patterns characteristic for American, Italian, and red-colored kale cultivars. Moreover, we demonstrated a tendency of high zeaxanthin proportions under traditional harvest conditions, which accord to low-temperature regimes. We also compared the carotenoid patterns of self-generated hybrid lines. Corresponding findings indicated that crossbreeding has a high potential for carotenoid content optimization in kale. KEYWORDS: Brassica oleracea var. sabellica, ß-carotene, lutein, (9Z)-neoxanthin, zeaxanthin, low temperature
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INTRODUCTION In plants, carotenoids are known as isoprenoid-derived compounds affecting natural pigmentation. Although they are best known for yellow to red coloring of fruits and flowers, carotenoids are generally present in all green tissues.1 Their structure is mainly characterized by a chromophore of conjugated double bonds (see Figure 1), which make carotenoids highly sensitive to isomerization and degradation processes.1 Oxygenated derivatives are better known as xanthophylls. Whereas lutein represents a xanthophyll containing one ß- and one ε-end group, zeaxanthin, as precursor of neoxanthin and violaxanthin, is characterized by two ß-end groups. Zeaxanthin and violaxanthin are involved in the socalled light xanthophyll-cycle reaction.2 These oxygenated derivatives are convertible into each other in a light-dependent reaction and play a key role in photoprotection of photosystem II.3 Under excess light conditions, zeaxanthin is accumulated. It binds to chlorophyll to form light-harvesting complexes. In contrast, violaxanthin levels increase under low-light conditions.3,4 The xanthopyll lutein is also involved in light stress responses. It is the most abundant xanthophyll in higher plants and plays an important role in antenna-protein stabilization, light harvesting by excitation energy transport to chlorophylls, and free radical quenching.3 Apart from their involvement in photoprotection as scavengers of reactive oxygen species (ROS),5 xanthophylls are also involved in several other stress responses. For instance, neoxanthin positively influences ABA (abscisic acid) accumulation in response to dehydration.6 The phytohormone ABA influences almost all aspects of plant growth and flowering © 2016 American Chemical Society
cascades, as well as it affects seed maturation and seed dormancy, stomatal closure, and plant stress responses.6 Scientific interest in carotenoids has not only been stirred by their numerous physiological functions in plants. In general, carotenoids play an important role as precursor of retinol (vitamin A).5 Especially ß-carotene provides high provitamin A activity.7 Moreover, carotenoids play an important role as natural source of antioxidant substances, which are able to bind to free radicals in animal cells.8 Furthermore, carotenoids considered in this study have been the subject of medical research in additional manners: Lutein and zeaxanthin are known for their health-promoting effect by eye disease prevention through absorbing blue light.7 Both substances have further been analyzed in epidemiological and clinical studies of age-related macular degeneration and cataracts.7,9 ßCarotene is supposed to have a great potential in prevention of oral, pharynx, and larynx cancers.5 Moreover, suppressive effects of neoxanthin on 3T3-L1 cell differentiation by lipid accumulation and enzyme activity reduction have been found.10 In Brassica, ß-carotene and lutein represent the most dominant carotenoids.8,11 Brassica species are of great economic importance as vegetable crops, oilseeds, forages, and condiments. Its worldwide production amounted to 93.7 million tons (kale, cauliflower, broccoli, cabbage, and other Brassica) in 2013.12 Received: Revised: Accepted: Published: 3251
January 18, 2016 March 18, 2016 April 5, 2016 April 5, 2016 DOI: 10.1021/acs.jafc.6b00268 J. Agric. Food Chem. 2016, 64, 3251−3257
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Journal of Agricultural and Food Chemistry
Figure 1. Overview of chemical structures of main carotenoids and GGPP (geranylgeranyldiphosphate), the shared precursor of carotenoids and chlorophylls.
we investigated the impacts of crossbreeding on carotenoid profiles to test the predictability of carotenoid composition in hybridization of kale varieties. In total, carotenoid values of 33 B. oleracea var. sabellica (kale) cultivars have been analyzed to identify cultivars providing the highest carotenoid contents. Selected cultivars differ in their morphological traits and in their geographical background. We also included self-generated hybrid lines in our analyses. Considering crossbreeding and leaf coloring effects as well as geographic origin of cultivars, multiple perspectives of comparison are provided.
In the United States, nearly 6 300 acres have been used for kale production in 2012, which corresponds to an increase of ∼35% in the last five years.13 Whereas Brassica species are a great resource for carotenoids and antioxidants in general, kale is reported to contain much higher ß-carotene, as well as lutein plus zeaxanthin, levels than broccoli, cauliflower, cabbage, or Brussels sprouts (2.84−9.23 mg/100 g of edible portion; 3.04− 39.55 mg/100 g of edible portion).8 Unfortunately, most previous studies considered single cultivars only,14,15 whereas intraspecific variability in carotenoids has rarely been investigated. Nevertheless, there is strong evidence for high intraspecific variability. Large differences in carotenoid single contents were found in pale green and purple kohlrabies (Brassica oleracea var. gongylodes).16 With regards to total carotenoid contents, values of nine different broccoli genotypes (Brassica oleracea var. italica) varied between 137.4 and 253.9 μg/g of dry weight.17 Further evidence for intraspecific carotenoid profile differences was found in kale.18 On the basis of these finds, our study aims to answer the question of how strong carotenoid profiles and single contents differ among kale cultivars. Knowledge on these intercultivar differences is not only useful to enhance medical research but also enables more purposeful breeding. In parallel,
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MATERIALS AND METHODS
Plant Material. Plants were grown under natural conditions in the botanic garden at Carl von Ossietzky University Oldenburg, Northern Germany. Whole adult leaves were harvested in December at noon, stored at −80 °C, and freeze-dried. At the date of harvest, all selected plants were 38 weeks old except for the American types ‘Vates’, ‘Southern Georgia’, ‘Champion’, and ‘Morris Heading’, which were 12 weeks younger. Although there was a difference in total plant age, all leaves harvested provided the same developmental stage and environmental influences to guarantee comparability. We defined the groups “American types” comprising ‘Vates’, ‘Georgia Southern’, ‘Morris Heading’, and ‘Champion’; “German landraces” including 3252
DOI: 10.1021/acs.jafc.6b00268 J. Agric. Food Chem. 2016, 64, 3251−3257
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Figure 2. Characteristic chromatogram (450 nm) of carotenoids and chlorophylls in kale (Brassica oleracea var. sabellica; ‘Winnetou’): 1, (9Z)neoxanthin; 2, chlorophyll a; 3, lutein; 4, zeaxanthin; 5, chlorophyll b; 6, ß-carotene. ‘Ditzum’, ‘Buss Bunde’, ‘Rosenweide’, ‘Schatteburg’, ‘Lage’, ‘Neuefehn’, ‘Lammertsfehn’, and ‘Diepholzer’; “German commercial” comprising ‘Jellen’, ‘Reflex’, ‘Lerchenzunge’, ‘Frostara’, ‘Halbhoher Grüner Krauser’, and ‘Winnetou’; “Italian varieties” including ‘Palmizio’, ‘Negro Romano’, and ‘Black Tuscany’; and “red-colored varieties” consisting of ‘Redbor’, ‘Rote Palme’, and ‘Holtefehn’. These sets have been determined based on geographical characteristics as well as correlating morphological features (see also Figure 5). Cultivars considered additionally are listed in the Supporting Information (Table 1). Carotenoid Analyses. The following chemicals and reagents were used for the analyses: methanol (99.95%) and ammonium acetate (Carl Roth GmbH and Co. KG, Germany); tetrahydrofuran (99.7%; VWR International GmbH, Germany); and methyl tert-butyl ether (99.8%; Chemsolute, Geyer GmbH & Co. KG, Germany). Dichloromethane (99.9%), isopropanol (99.95%), α-carotene, (9Z)-neoxanthin, and zeaxanthin were purchased from CaroteNature GmbH (Switzerland), and β-carotene and chlorophylls a and b were purchased from Sigma-Aldrich Co. LLC Chemie GmbH (Germany). Lutein was isolated from Tagetes erecta L.19 Carotenoids were extracted two times from 10 mg leaf material using 0.5 mL of methanol/tetrahydrofuran solution (1:1, v/v). The extracts were shaken at 1000 rpm for 5 min at room temperature and centrifuged at 4500 rpm for 5 min at 20 °C. The combined extracts were evaporated in a stream of nitrogen. Extracts were dissolved in 0.02 mL of dichloromethane and 0.18 mL of isopropyl alcohol. Prior to analysis, solutions were filtered through a 0.2 μM polytetrafluoroethylene (PTFE) membrane and kept at 4 °C in the autosampler during the analysis. Separation was performed with a C30-column (YMC Co. Ltd. Japan, YMC C30, 100 × 2.1 mm, 3 μm) on an Agilent Technologies 1290 Infinity ultrahigh-performance liquid chromatograph (UHPLC) (Santa Clara, U.S.A.). Mixtures of methanol, methyl-tert-butyl ether, and water in different volume ratios (solvent A = 81/15/4 and solvent B = 6/90/4) were used as mobile phases at a flow rate of 0.2 mL min−1. Carotenoids were separated in gradient mode from 100% (10 min isocratic) to 0% solvent A within 60 min. To enhance ionization, 20 mM ammonium acetate was added to the mobile phases. Pigments were analyzed on an Agilent Technologies 6230 time-offlight (TOF) LC/MS equipped with an atmospheric-pressure chemical ionization (APCI) ion source in positive ionization mode. Gas temperature was set to 325 °C at a flow rate of 8 L min−1, the vaporizer was set to 350 °C, and nebulizer pressure was set to 35 psi. Voltage was set to 3500 V, and a fragmentor voltage of 175 V was applied at a corona current of 6.5 μA. Stock solutions of authentic standards were prepared individually, and concentrations were determined spectrophotometrically using the specific wavelengths and extinction coefficients.20,21 Compounds were identified by cochromatography with reference substances using chlorophyll a and b, the (all-E)-isomers for ß-carotene, lutein, and zeaxanthin, and (9Z)neoxanthin. External standard calibration curves were used for quantification by dose−response curves. Statistical Analyses. All values given in this study are averages of double measurements. Box plot analyses as well as significance
calculations have been performed in R (version 3.2.0). Correlations have been estimated using the Pearson r correlation test.
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RESULTS
In the comparison of 33 different varieties of kale, large variations in quality and quantity of carotenoid profiles as well as general trends have been noticed (Supporting Information). The chromatogram of cultivar ‘Winnetou’ shows the characteristic peaks corresponding to (9Z)-neoxanthin, chlorophyll a, lutein, zeaxanthin, chlorophyll b, and ß-carotene (Figure 2). Zeaxanthin was the most dominant carotenoid in 21 out of 33 cultivars, with the highest values found in the American types ‘Vates’ and ‘Champion’ (1.613 and 2.460 mg/g of dry weight, respectively). In contrast, the lowest amounts have been found for either (9Z)-neoxanthin or ß-carotene. These carotenoids estimated about 0.12 ± 0.07 and 0.1 ± 0.04 mg/g of dry weight on average. Large differences were found in terms of carotenoid quantity. Total carotenoid contents varied by a factor of 6.0 between 0.5 mg/g of dry weight found in wild kale and 3.0 mg/g of dry weight detected in the American cultivar ‘Champion’. Variation by a factor of 4.4 was found for ßcarotene, ranging between 0.045 mg/g of dry weight (‘Ditzum’) and 0.2 mg/g of dry weight (‘Holtefehn’). Zeaxanthin and (9Z)-neoxanthin levels varied by a factor of 12.5 and 8.8 (0.2 mg/g of dry weight in wild kale and 2.5 mg/g of dry weight in ‘Champion’; 0.04 mg/g of dry weight in wild kale and 3.5 mg/g of dry weight in ‘Redbor’, respectively). Variation by a factor of 3.5 was found in the case of lutein. Its levels varied between 0.2 and 0.7 mg/g of dry weight (wild kale and ‘Negro Romano’) and have been comparably high in all Italian varieties. Among single compounds, several high correlations have been found. An overview on these correlations is given in Figure 3. It is conspicuous that the content of zeaxanthin is apparently uncorrelated with those of other carotenoids,
Figure 3. Overview of correlations found between single carotenoid and chlorophyll contents in kale varieties (Brassica oleracea var. sabellica). Values present results of Pearson R correlation tests. Data lower than 0.5 have been excluded. 3253
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Figure 4. Box-plot analyses on single carotenoids and chlorophylls a and b contents found in kale varieties sorted according to the predetermined set of cultivars. Significances are given according to “tukey” analyses. Significant values are signed with a single star (*).
Figure 5. Percentage distribution of single carotenoids and chlorophylls a and b found in kale varieties sorted according to their historical and geographical background correlating to morphological unique attributes. Representative illustrations are given for all sets except for hybrid lines due to their morphological variability (bars represent 2 cm).
whereas contents of chlorophyll a and lutein correlated strongly with every other substance considered. The strongest correlation (r = 0.933) exists between lutein and chlorophyll b values, followed by a correlation between chlorophyll a and ßcarotene contents (r = 0.906). Significant trends were found in statistical comparisons between our six defined sets of varieties (see above). We found that chlorophyll a contents of red-colored varieties are significantly higher than those of American varieties, German landraces, or hybrid lines (Figure 4a). For chlorophyll b and
lutein, red-colored and Italian varieties provide significantly higher values than any other cultivar set (Figure 4b, c). In the case of ß-carotene, contents of red-colored varieties are exceptional (Figure 4d), whereas significantly higher (9Z)neoxanthin values are almost exclusively for Italian varieties (Figure 4e). Zeaxanthin is the only compound that did not exhibit significant alterations among cultivar sets (Figure 4f). In contrast to wild kale, all cultivars provide higher proportions of zeaxanthin (see Figure 5 for comparison). The two most similar cultivar sets are Italian and red-colored 3254
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variation in lutein and ß-carotene values were reported by a factor of ∼2.5.18 In our study, carotenoid content variability ranged from a factor of 3.5 in the case of lutein up to a factor of 12.5 in the case of zeaxanthin. Lutein and ß-carotene are generally known to be the dominant carotenoids in Brassica.11 Under cold-stress conditions, we found that this general statement is only valid to a certain degree. Low temperatures affect carotenoid content by increasing the level of xanthophyll pigments, whereas ßcarotene contents decrease.23,24 Xanthophyll accumulation at low-temperature counteracts photoinhibition.25 Thus, a conversion of violaxanthin to zeaxanthin in winter-stress conditions was reported in Oxyria digyna.26 Increased zeaxanthin levels under cold-stress conditions were also reported for two high mountain plant species (Soldanella alpina and Ranunculus glacialis).27 In Arabidopsis, high-light and low-temperature related stress symptoms have shown to be reduced in zeaxanthin-accumulating plants.28 In accordance, accumulation by a factor of up to four was found in Yucca plants regarding two xanthophylls including zeaxanthin during autumn, while ßcarotene levels decreased.29 These low ß-carotene contents are regulated by high ß-hydroxylase activity, which converts ßcarotene to zeaxanthin.4 Leaf material used in our study was collected in December in northern Germany. Zeaxanthin was the most abundant carotenoid in the majority of cases, followed by lutein. In nine cases, lutein values have been slightly higher than those of zeaxanthin. These cultivars do not demonstrate any obvious similarity and comprise German as well as Italian, American, and red-colored varieties. The general pattern is further complemented by comparably low ß-carotene and (9Z)neoxanthin levels. These results support the assumption of a dominance shift in carotenoid composition in cold-temperature regimes to high contents of zeaxanthin by parallel decreasing ßcarotene levels. Carotenoids and chlorophylls share common precursors in their biosynthesis2 and are functionally highly linked. Zeaxanthin and lutein can bind to chlorophylls to form lightharvesting complexes (Lhc’s).30 The two carotenoid subclasses containing either one ß- and one ε-end group (such as lutein) or two ß-end groups (including ß-carotene and zeaxanthin) are synthesized by β-lycopene cyclases and ε-lycopene cyclases, which show highly correlated activities (r = 0.71).2 Conversions between ß-carotene and zeaxanthin as well as between zeaxanthin and violaxanthin are regulated by single enzymes, which also cause strong correlation patterns.4 Previous studies support strong correlations between single carotenoids and chlorophyll contents. For instance, correlation coefficients between lutein and ß-carotene, chlorophylls a and b values, ß-carotene and chlorophylls a and b, and chlorophylls a and b have been estimated in 23 kale cultivars.18 Our results do support similar correlations between main carotenoids and chlorophyll contents. Furthermore, they provide further insights by including (9Z)-neoxanthin and zeaxanthin in the account. In the case of zeaxanthin, no linear correlation is supported. In contrast, (9Z)-neoxanthin values are highly correlated with those of lutein and chlorophyll a and b (r = 0.820, r = 0.520, and r = 0.805, respectively). Further analyses should investigate correlation patterns between all substances involved in the xanthophyll cycle (violaxanthin, antheraxanthin, zeaxanthin, diadinoxanthin, and diatoxanthin).31
varieties, while American varieties and hybrid lines exhibit a quite distinct carotenoid profile. The American varieties contain 29% higher zeaxanthin proportions compared to wild kale, but also 17% less chlorophyll a. These tendencies are shared with the hybrid lines. Whereas zeaxanthin proportions are similar between American varieties and hybrid lines, the hybrid lines contain even lower chlorophyll a percentages (18% compared to 44% in wild kale). The trend toward higher zeaxanthin proportion is to some degree also detectable in German commercials and German landraces. These two groups demonstrate almost identical characteristics on the level of relative distribution patterns. Finally, five first-generation hybrid lines have been analyzed in comparison to their parental lines. General tendencies with regard to carotenoid and chlorophyll content patterns are depicted in Figure 6. Overall, the hybrid lines provide lower
Figure 6. Exemplary illustration giving the carotenoid and chlorophyll content pattern of two kale varieties (‘Buss Bunde’ and ‘Lage’) and their hybrid.
chlorophyll a and b, lutein, and ß-carotene values. The opposite trend is noticeable for zeaxanthin. In four out of five cases, zeaxanthin contents of hybrid lines are higher than those of the parent lines (see Supporting Information).
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DISCUSSION To estimate carotenoid profiles of kale and its variability among cultivars, we analyzed 28 different kale cultivars and five firstgeneration hybrid lines. Our results demonstrate high zeaxanthin proportions under low-temperature regimes. We further found correlations between red-colored leaves and single carotenoid levels. Finally, significant impacts of hybridization on total carotenoid content have been found. Intraspecific differences in carotenoid contents have been reported for other Brassica species and Brassica oleracea subspecies including cabbage (Brassica oleracea. L. var. capitata), Chinese cabbage (Brassica rapa L. pekinensis (Lour.) Olsson), cauliflower (Brassica oleracea L. var. botrytis), broccoli (Brassica oleracea L. var. italica Plenck.), and Brussels sprouts (Brassica oleracea L. var. gemmiferae Zenk.).22 For instance, lutein differences in cabbage were found to differ by a factor of 13, followed by ß-carotene variation by a factor of 12.22 In other studies, intercultivar differences have been reported to be much lower. Comparing 23 kale varieties in America, intraspecific 3255
DOI: 10.1021/acs.jafc.6b00268 J. Agric. Food Chem. 2016, 64, 3251−3257
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Journal of Agricultural and Food Chemistry Influence of Morphological Traits and Geographic Origins. By comparing secondary metabolite profiles of pale green and purple kohlrabi types (Brassica oleracea var. gongylodes), higher contents of carotenoids in the green type were found.16 Single substances differed in comparisons by 157% and 130% for ß-carotene and lutein, respectively, between both varieties. Our carotenoid results illustrate the opposite trend with higher levels of ß-carotene and lutein in the red-colored kale types. Additionally, red-colored varieties contain significantly more chlorophyll a and b. These findings suggest a higher photosynthetic potential of red-colored varieties associated with an accumulation of photoprotective substances. The Italian kale set demonstrated specific, significant trends as well. In this case, chlorophyll b, lutein, and (9Z)-neoxanthin values were significantly higher. Neoxanthin is known to promote ABA (abscisic acid) accumulation in response to stress. 6 Low-temperature stress has a cell dehydrative component, which is counteracted by ABA-induced dehydrin accumulation.32 Thus, accumulation of (9Z)-neoxanthin may be indicative for ABA accumulation to prevent frost-related cell dehydration. American varieties can clearly be distinguished from other kale cultivars based on their extraordinary proportion of zeaxanthin. Zeaxanthin is involved not only in photoinhibition but also in several stress-response mechanisms.4,33 One explanation for this high zeaxanthin proportion might be a stronger stress reaction in response to low temperatures. Whereas red-colored as well as Italian and American varieties exhibited specific characteristics, German commercial kales cannot be clearly distinguished from German landraces based on their main carotenoid and chlorophyll contents. From this perspective, influences of commercial breeding in secondary metabolite profiles of kales cannot be determined. Effect of Crossbreeding. The concrete question of how carotenoid profiles differ between parent and hybrid lines is not pursued frequently. We expected the analyzed hybrid lines to show a similar profile to one parent line, as has been demonstrated for carotenoids in pepper.34 However, this study provided only a skin-deep comparison. Further support for our initial hypothesis comes from analyses on an intergeneric hybrid of Brassica napus by morphological, cytological, and molecular means.35 Although intermediate morphological features have been found in these hybrids, a biased distribution toward the B. napus parent in regard to the fatty acid composition was reported. When analyzing the phenolic glycoside and condensed tannin profiles of a Salix sericea and S. eriocephala hybrid, a greater variation in the expression of chemical phenotypes in F1 and F2 generations was found.36 Moreover, the same working group found a heterosis effect in regard to stress tolerance so that damaged F1 hybrid plants produced more biomass than undamaged plants. This overcompensating stress response was contrary to observations made for both parent lines.37 Results of our comparison might indicate a similar shift in stress response. Contrary to our expectations, most carotenoids were detected in lower quantity in hybrid lines. The only exception to this pattern was zeaxanthin. With regard to the chlorophyll fluorescence-quenching ability of zeaxanthin31 and its involvement in several stress-response mechanisms,4,33 its accumulation in hybrid lines may be related to a stronger lowtemperature stress response.
In summary, results of this study underline the great intraspecific variability in kale carotenoid profiles. While no clear distinguishable difference was found between German landraces and German commercial varieties, characteristic tendencies of American, Italian, and red-colored varieties were detected. Further investigations should therefore consider these sets of kale varieties. Moreover, ABA measurements are recommended to determine how zeaxanthin and (9Z)-neoxanthin accumulations in low-temperature regimes correlate to ABA concentrations. For this purpose, other carotenoids involved in the xanthophyll cycle, which are supposed to show similarly strong correlations, should also be considered. Knowledge of intercultivar differences enables targeted variety selection in order to receive the highest single carotenoid levels usable for human health-promoting studies. Despite variety-set specific patterns, this study demonstrated that crossbreeding has a great impact on carotenoid profiles and total contents in kale. However, understanding causal differences of carotenoid contents in hybrids is currently lacking due to focused studies.
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ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jafc.6b00268. Table of quantitative results of carotenoid analysis from leaf material from 33 varieties of kale (Brassica oleracea var. sabellica) considering the carotenoids ß-carotene, lutein, neoxanthin, and zeaxanthin as well as chlorophyll a and b (PDF)
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS We would like to thank Christoph Hahn, Jan von Hacht, Andrea Jankowsky, Jane Looschen, and Annett Platalla for laboratory assistance. We also thank Niklas Buhk for his support in data analysis and Reinhard Lühring for providing seeds of German landrace varieties.
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ABBREVIATIONS USED ABA,abscisic acid; Chl a,chlorophyll a; Chl b,chlorophyll b; DW,dry weight; GAP,glyceraldehyde 3-phosphate; GGPP,geranylgeranyldiphosphate
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REFERENCES
(1) Bramley, P. M. Isoprenoid metabolism. Plant Biochemistry; Dey, P. M., Harborne, J. B., Eds.; Academic Press: London, 1997; pp 417− 434. (2) Ruiz-Sola, M. A.; Rodriguez-Concepción, M. Carotenoid biosynthesis in arabidopsis: a colourful pathway. ASPB 2012, 10, e0158. (3) Jahns, P.; Holzwarth, A. R. The role of xanthophylls cycle and of lutein in photoprotection of photosystem II. Biochim. Biophys. Acta, Bioenerg. 2012, 1817, 182−193. (4) Hannoufa, A.; Hossain, Z. Regulation of carotenoid accumulation in plants. Biocatal. Agric. Biotechnol. 2012, 1, 198−202. (5) Fiedor, J.; Burda, K. Potential role of carotenoids as antioxidants in human health and disease. Nutrients 2014, 6, 466−488.
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DOI: 10.1021/acs.jafc.6b00268 J. Agric. Food Chem. 2016, 64, 3251−3257
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Journal of Agricultural and Food Chemistry (6) North, H. M.; De Almeida, A.; Boutin, J.-P.; Frey, A.; To, A.; Botran, L.; Sotta, B.; Marion-Poll, A. The Arabidopsis ABA-deficient mutant aba4 demonstrates that the major route for stress-induced ABA accumulation is via neoxanthin isomers. Plant J. 2007, 50, 810− 824. (7) Krinsky, N. I.; Johnson, E. J. Carotenoid actions and their relation to health and disease. Mol. Aspects Med. 2005, 26, 459−516. (8) Podsedek, A. Natural antioxidants and antioxidant capacity of Brassica vegetables: A review. LWT 2007, 40, 1−11. (9) Abdel-Aal, E.-S. M.; Akhtar, H.; Zaheer, K.; Ali, R. Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health. Nutrients 2013, 5, 1169−1185. (10) Okada, T.; Nakai, M.; Maeda, H.; Hosokawa, M.; Sashima, T.; Miyashita, K. Suppressive effect of neoxanthin on the differentiation of 3T3-L1 adipose cells. J. Oleo Sci. 2008, 57 (6), 345−351. (11) Kopsell, D. A.; McElroy, J. S.; Sams, C. E.; Kopsell, D. E. Genetic variation in carotenoid concentrations among diploid and amphidiploid rapid-cycling Brassica species. HortScience 2007, 42 (3), 461−465. (12) Food and Agriculture Organization of the United Nations (FAO) website, FAO stats; http://faostat3.fao.org (accessed Aug 5, 2015). (13) USDA NASS, 2012 Census of Agriculture; www.agcensus.usda. gov/Publications/2012/ (accessed Aug 5, 2015). (14) Tuan, P. A.; Park, N. I.; Park, W. T.; Kim, Y. B.; Kim, J. K.; Lee, J.; Lee, S. H.; Yang, T.-J.; Park, S. U. Carotenoid accumulation and expression of carotenogenesis genes during seedling and leaf development in Chinese cabbage (Brassica rapa subsp. pekinensis). Plant OMICS J. 2012, 5 (2), 143−148. (15) Pham, A. T.; Kim, J. K.; Lee, J.; Park, W. T.; Kwon, D. Y.; Kim, Y. B.; Kim, H. H.; Kim, H. R.; Park, S. U. Analysis of carotenoid accumulation and expression of carotenoid biosynthesis genes in different organs of chinese cabbage (Brassica rapa subsp. pekinensis). EXCLI J. 2012, 11, 508−516. (16) Park, W. T.; Kim, J. K.; Park, S.; Lee, S.-W.; Li, X.; Kim, Y. B.; Uddin, M. R.; Park, N. I.; Kim, S.-J.; Park, S. U. Metabolic profiling of glucosinolates, anthocyanins, carotenoids, and other secondary metabolites in kohlrabi (Brassica oleracea var. gongylodes). J. Agric. Food Chem. 2012, 60, 8111−8116. (17) Farnheim, M. W.; Kopsell, D. A. Importance of genotype on carotenoid and chlorophyll levels in broccoli heads. HortScience 2009, 44 (5), 1248−1253. (18) Kopsell, D. A.; Kopsell, D. E.; Lefsrud, M. G.; CurranCelentano, J.; Dukach, L. E. Variation in lutein, ß-carotene, and chlorophyll concentrations among Brassica oleracea cultigens and seasons. HortScience 2004, 39 (2), 361−364. (19) Errard, A.; Ulrichs, C.; Kühne, S.; Mewis, I.; Drungowski, M.; Schreiner, M.; Baldermann, S. Single- versus multiple-pest infestation affects differently the biochemistry of tomato (Solanum lycopersicum ‘Ailsa Craig’). J. Agric. Food Chem. 2015, 63 (46), 10103−10111. (20) Britton, G., Liaaen-Jensen, S., Pfander, H., Eds. Carotenoids: Spectroscopy; Birkhaueser: Basel, Switzerland, 1995; Vol. 1B, pp 1−378. (21) Krumbein, A. Schnelle HPLC-Methode zur Bestimmung der Carotinoide und Chlorophylle in Brokkoli. Dtsch. Ges. Qual. 1996, 31, 41−44. (22) Singh, J.; Upadhyay, A. K.; Prasad, K.; Bahadur, A.; Rai, M. Variability of carotenes, vitamin C, E and phenolics in Brassica vegetables. J. Food Compos. Anal. 2007, 20 (2), 106−112. (23) Savitch, L. V.; Leonardos, E. D.; Krol, M.; Jansson, S.; Grodzinski, B.; Huner, N. P. A.; Ö quist, G. Two different strategies for light utilization in photosynthesis in relation to growth and cold acclimation. Plant, Cell Environ. 2002, 25, 761−771. (24) Demming-Adams, B.; Adams, W. W.; Ebbert, V.; Logan, B. A. Ecophysiology of the xanthophyll cycle. In the Photochemistry of Carotenoids; Frank, H. A., Young, G., Britton, G., Cogdell, R. J., Eds.; Kluwer Academic Publishers: Dordrecht, The Netherlands, 1999; pp 245−269.
(25) Schöner, S.; Krause, G. H. Protective systems against active oxygen species in spinach: Response to cold acclimation in excess light. Planta 1990, 180, 383−389. (26) Ö quist, G.; Gardeström, P.; Huner, N. P. A. Metabolic changes during cold acclimation and subsequent freezing and thawing. In Conifer Cold Hardiness; Bigras, F. J., Colombo, S. J., Eds.; Kluwer Academic Publishers: Dordrecht, The Netherlands, 2001; pp 137− 163. (27) Streb, P.; Aubert, S.; Gout, E.; Bligny, R. Reversibility of coldand light-stress tolerance and accompanying changes of metabolite and antioxidant levels in the two high montain plant species Soldanella alpina and Ranunculus glacialis. J. Exp. Bot. 2003, 54 (381), 405−418. (28) Johnson, M. P.; Havaux, M.; Triantaphylidès, C.; Ksas, B.; Pascal, A. A.; Robert, B.; Davison, P. A.; Ruban, A. V.; Horton, P. Elevated zeaxanthin bound to oligomeric LHCII enhances the resistance of Arabidopsis to photo oxidative stress by light protective, antioxidant mechanism. J. Biol. Chem. 2007, 282, 22605−22618. (29) Adams, W. W.; Barker, D. H. Seasonal changes in xanthophyll cycle-dependent energy dissipation in Yucca glauca Nuttall. Plant, Cell Environ. 1998, 21, 501−511. (30) Dall'Osto, L.; Cazzaniga, S.; Havaux, M.; Bassi, R. Enhanced photoprotection by protein-bound vs. free xanthophyll pools: a comparative analysis of chlorophyll b and xanthophyll biosynthesis mutants. Mol. Plant 2010, 3 (3), 576−593. (31) Young, A. J.; Frank, H. A. Energy transfer reactions involving carotenoids: quenching of chlorophyll fluorescence. J. Photochem. Photobiol., B 1996, 36, 3−15. (32) Hanin, M.; Brini, F.; Ebel, C.; Toda, Y.; Takeda, S.; Masmoudi, K. Plant dehydrins and stress tolerance − versatile proteins for complex mechanisms. Plant Signaling Behav. 2011, 6 (10), 1503−1509. (33) Havaux, M.; Eymery, F.; Porfirova, S.; Rey, P.; Dörmann, P. Vitamin E protects against photoinhibition and photooxidative stress in Arabidopsis thaliana. Plant Cell 2005, 17, 3451−3469. (34) Biacs, P. A.; Daood, H. G.; Huszka, T. T.; Biacs, P. K. Carotenoids and carotenoid esters from new cross-cultivars of paprika. J. Agric. Food Chem. 1993, 41, 1864−1867. (35) Hu, Q.; Hansen, L.; Laursen, J.; Dixelius, C.; Andersen, S. Intergeneric hybrids between Brassica napus and Orychophragmus violaceus containing traits of agronomic importance for oilseed rape breeding. Theor. Appl. Genet. 2002, 105, 834−840. (36) Orians, C. M.; Griffiths, M. E.; Roche, B. M.; Fritz, R. S. Phenolic glycosides and condensed tannins in Salix sericea, S. eriocephala and their F1 hybrids: not all hybrids are created equal. Biochem. Syst. Ecol. 2000, 28, 619−632. (37) Hochwender, C. G.; Fritz, R. S.; Orians, C. M. Using hybrid systems to explore the evolution of tolerance to damage. Evol. Ecol. 2000, 14, 509−521.
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DOI: 10.1021/acs.jafc.6b00268 J. Agric. Food Chem. 2016, 64, 3251−3257
