Article

Pigments in Citrus

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Citrus fruits include diverse types and contain various carotenoids and flavonoids, which may provide enhanced nutrients and beneficial nutraceuticals in the human diet. Carotenoids are the primary pigments for characteristic yellow to red colors and organoleptic attractions in different citrus fruits, while anthocyanins, a subgroup of colored flavonoids, independently yield “blood” red flesh only in blood oranges. Lycopene is the carotenoid for pink to deep red flesh in some grapefruits and oranges. Most genes in the two pathways are cloned and characterized, and the regulatory genes and mechanisms are being gradually uncovered primarily through comparison of red-fleshed mutants with their progenitors. Such knowledge will greatly facilitate continued varietal improvement for these beneficial components. Dietetics of citrus fruits and juice has been studied from both nutritional and preventive medicinal perspectives, with emphasis on lycopene and anthocyanins due to the special red color and predominant content in popular red-fleshed cultivars. The benefits include higher quality and availability of nutrients, substantially improved health biomarkers for lipid profiles, lower risk of obesity and cardiovascular disease, and potential suppression of some cancers. Moderate regular consumption of 100 % orange juice and/or fresh citrus fruits should be encouraged to help individual children and adults meet the United States Department of Agriculture (USDA) daily recommendation for fruit intake and a healthy diet.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... One interesting group of Car-pigmented citrus fruits is those which accumulate lycopene (Fig. 12.5) such as red and pink grapefruits and pummelos, a few spontaneous sweet orange mutants such as CaraCara and Hong Anliu (recently reviewed in Refs. Chen et al., 2015)). In the lycopene-accumulating citrus varieties, the lycopene increases as the fruit ripens and is usually accompanied by a significant increment in phytoene and phytofluene, small to moderate of β-carotene, and a reduction in the downstream β,β-xanthophylls (Xu et al., 2006;Alquezar et al., 2008;Alquezar et al., 2013). ...
... For "blood oranges", anthocyanin content is a quality trait of paramount importance and is characterized by a high degree of variation from year to year, even within the canopy. This variation is imposed by several environmental factors, among which temperature is prevalent (Chen et al., 2015). ...
Article
Several studies in citrus-producing countries are currently being carried out to select and evaluate rootstocks that are tolerant to Citrus Tristeza Virus (CTV) and can be adopted in different citrus production areas. An evaluation of rootstock suitability must consider the productive and qualitative features as well as the adaptability to varied environmental conditions (i.e., soil characteristics). Additionally, some varieties present qualitative aspects that are appreciated by consumers but can be affected by the use of different rootstocks. In Italy, the qualitative traits of pigmented or blood oranges, which are characterized by the presence of anthocyanins in the peel and flesh, are strongly influenced by several factors, including the scion/rootstock combination. The objective of this study was to evaluate and compare the influence of ten rootstocks on yield precocity and fruit quality of ‘Tarocco Scirè’ pigmented sweet orange in a Sicilian area within the Protected Geographical Indication (GPI) “Arancia Rossa di Sicilia” production district. Five of the ten rootstocks, namely, ‘Bitters’, ‘Carpenter’, ‘Furr’, ‘F6P12®’ and ‘F6P13′, have recently been released and produced good yields in limiting soil conditions. In this study, the important role of rootstock in determining the organoleptic quality, specifically the sugar content, and the anthocyanin concentrations in both the pulp and the juice was demonstrated. Some of the rootstocks that were recently introduced in Italy, i.e., ‘Bitters’ and ‘Furr’, were promising because they positively influenced several agronomic and qualitative parameters in the tested conditions, positively affected the yield precocity and enhanced the fruit juice anthocyanin content. Overall, these results contribute to the assessment of the role of different rootstocks in the post-CTV Italian citrus industry.
... For "blood oranges", anthocyanin content is a quality trait of paramount importance and is characterized by a high degree of variation from year to year, even within the canopy. This variation is imposed by several environmental factors, among which temperature is prevalent (Chen et al., 2015). ...
Article
Several studies in citrus-producing countries are currently being carried out to select and evaluate rootstocks that are tolerant to Citrus Tristeza Virus (CTV) and can be adopted in different citrus production areas. An evaluation of rootstock suitability must consider the productive and qualitative features as well as the adaptability to varied environmental conditions (i.e., soil characteristics). Additionally, some varieties present qualitative aspects that are appreciated by consumers but can be affected by the use of different rootstocks. In Italy, the qualitative traits of pigmented or blood oranges, which are characterized by the presence of anthocyanins in the peel and flesh, are strongly influenced by several factors, including the scion/rootstock combination. The objective of this study was to evaluate and compare the influence of ten rootstocks on yield precocity and fruit quality of ‘Tarocco Scirè’ pigmented sweet orange in a Sicilian area within the Protected Geographical Indication (GPI) “Arancia Rossa di Sicilia” production district. Five of the ten rootstocks, namely, ‘Bitters’, ‘Carpenter’, ‘Furr’, ‘F6P12®’ and ‘F6P13′, have recently been released and produced good yields in limiting soil conditions. In this study, the important role of rootstock in determining the organoleptic quality, specifically the sugar content, and the anthocyanin concentrations in both the pulp and the juice was demonstrated. Some of the rootstocks that were recently introduced in Italy, i.e., ‘Bitters’ and ‘Furr’, were promising because they positively influenced several agronomic and qualitative parameters in the tested conditions, positively affected the yield precocity and enhanced the fruit juice anthocyanin content. Overall, these results contribute to the assessment of the role of different rootstocks in the post-CTV Italian citrus industry.
Article
Background Hong Jiang (HC), a grafted chimera of sweet orange (Citrus sinensis (L.) Osbeck), is prone to variations in fruit shape, taste, and pulp mastication. We studied the transcriptomes and metabolomes pf pulps of HC and its two variations (CB: fruits with changed pulp mastication, taste, and color and JB: fruits with changed pulp color and taste) to explore the related pathways. Results JB accumulated higher organic acids as compared to HC and CB. Flavonoid content was highest in HC followed by JB and CB. The soluble sugar content was lower, while cellulose content was higher in both JB and CB as compared to HC. We found 5,156 and 1,673 DEGs and 283 and 94 DAMs in HC vs JB and HC vs CB, respectively. The differential regulation of starch and sucrose metabolism, galactose metabolism, glycolysis/gluconeogenesis, fructose and mannose metabolism, and citrate cycle pathways could be associated with changes in sugar contents and tastes in JB and CB. Cell-wall polymers-related DEGs/DAMs were associated with the inferior mastication quality of JB and CB. Carotenoid biosynthesis possibly imparts yellowish and reddish pulp color in HC. Additional to this pathway, the anthocyanin biosynthesis led to the changes in JB and CB pulp color. Conclusions This combined methodological approach proved to be useful in delineating the large-scale changes in the transcripts and metabolites of variant fruits in a chimeric citrus variety. This study provides advanced and large-scale data on citrus taste, mastication, and pulp color.
Article
Anthocyanin concentration is considered an important fruit quality index of blood oranges and has gained popularity among consumers due to its antioxidant capacity, therapeutic properties, and prevention of some human diseases. Anthocyanin biosynthesis occurs in the cytoplasmic face of the endoplasmic reticulum by multi-enzymes complexes through the flavonoid pathway. Polyphenoloxidase (PPO) and β-glucosidase (anthocyanase) are the enzymes responsible for anthocyanin degradation. Blood oranges are cold-dependent for anthocyanin biosynthesis and accumulation, and thus, the low temperature of storage can enhance anthocyanin concentration and improve internal fruit quality. In addition, anthocyanin accumulation can be accelerated by postharvest technologies, either physical treatments or chemical elicitors. However, low temperatures can induce chilling injury (CI) incidence in blood oranges. Postharvest chemical elicitors treatments can enhance anthocyanin accumulation and prevent CI. This review provides the most updated information about postharvest tools modulating the anthocyanin content, and the role of enhancing and preserving pigmentation to produce blood orange with the highest quality standards.
Article
Flower and fruit color is one of the most important features of horticultural plants. Its formation and regulation are always affected by both internal and external factors. Among these factors, the UDP-glucose: flavonoid 3-O-glucosyltransferase (UFGTs) have a major role in the development and production of flowers and fruits colors. The UFGT enzymes are critical for upholding anthocyanin synthesis, acylation, and glucosylation in horticulture plants. The functions of the UFGT encoding genes in the formation of pigments, particularly anthocyanin, are summarized in this article. Furthermore, this review article emphasizes the joint role of the UFGTs and other downstream genes in the stabilization of anthocyanin in the final step. The advancement of flower and fruit color regulation research is discussed, with an emphasis on UFGT genes. To give a wide context for flower and fruit color improvements in horticultural plants, the limitations of flower and fruit color research as well as prospective areas for future development are also scrutinized. This review provided resources for a better understanding of the role of UFGT genes in the color formation of flowers and fruits of horticultural plants.
Article
Anthocyanins, one of the major plant pigments, are responsible for the coloration of various plant tissues and organs, including fruits. They are known to have significant health benefits. Anthocyanin biosynthesis is influenced by environmental factors such as cold temperature and is transcriptionally regulated by MYB/bHLH/WD40 complexes composed of R2R3-MYB, basic helix-loop-helix (bHLH), and WD40-type transcription factors (TFs). The Ruby locus, which encodes a MYB TF, controls anthocyanin production in the fruit of blood orange varieties in a dominant manner. For the marker-assisted selection of citrus breeding lines with high anthocyanin production, we established PCR-based molecular markers for robust genotyping of Ruby locus alleles. Two dominant Ruby alleles, RD-1 and RD-2, were specifically detected in the blood orange varieties with high anthocyanin contents in their fruit flesh, but not in the varieties rich in lycopene. For functional analysis of Ruby alleles, we generated transgenic Arabidopsis expressing a functional wild-type R, a non-functional r-1, or a dominant RD-2 allele. Expression levels of flavonoid/anthocyanin biosynthetic genes and anthocyanin production were highly increased in the transgenic plants expressing the dominant Ruby allele by its retrotransposon-mediated native promoter under cold treatment, suggesting that the retrotransposon may contain cis-regulatory elements that respond to cold temperature. Our results also support that the MYB TF encoded by Ruby could be a key component of regulatory complexes that control flavonoid/anthocyanin biosynthesis in citrus.
Chapter
Pigments in citrus fruit include chlorophylls, carotenoids, and flavonoids. While chlorophylls color green citrus fruit, carotenoids and flavonoids are synthesized predominantly in citrus fruit after the color breaker stage. Various carotenoids are responsible for a spectrum of characteristic red, orange, and yellow colors for mature citrus fruit. Lycopene is the carotenoid producing pink to red in some sweet orange and grapefruit mutants while other carotenes and xanthophylls contribute to commonly seen orange to yellow colors. Anthocyanins, a subgroup of colored flavonoids, yield additional blood red colors only in blood oranges. Citrus fruit mutants rich in red lycopene or anthocyanins that generate additional organoleptic attraction and marketing appeal have been extensively used in various pigment studies and comparisons. Most biosynthetic genes and some regulatory genes in the carotenoid and anthocyanin pathways have been cloned and characterized. Pigmentation and gene expression changes during citrus fruit postharvest degreening and storage were also gradually uncovered. Genetic knowledge of citrus fruit pigmentation facilitates continuing research on and variety improvement for beneficial pigment compounds. Dietetics of some citrus pigments has been studied from both nutritional and preventive medicinal perspectives, with emphasis on lycopene and anthocyanins due to the predominant content in popular red-fleshed cultivars, special marketing appeal, and potential health benefits. Nutraceutical and medicinal benefits of consumption of citrus fruit (juice) include substantially improved health biomarkers for lipid profiles, low risk of obesity and cardiovascular disease, and potential suppression of some cancers. Regular moderate consumption of fresh citrus fruit and/or orange juice should be encouraged as part of a daily healthy diet.
Article
Full-text available
Citrus is a globally consumed fruit with great popularity. Mandarin (Citrus reticulata cv. ‘Shatangju’) is a local variety, and its planting area and yield are the greatest regarding fruit tree planting in Guangdong Province, China. However, its resistance to Huanglongbing (HLB) is weak. After infection by HLB, the fruits cannot develop normally. In this study, four kinds of fruits were classified as HBG, XQG, ZQG, and DHG, according to the color of their peels. The metabolomes of the three abnormally colored groups (HBG, XQG, and ZQG) and the normally colored group (DHG) were compared using a UPLC-QQQ-MS-based metabolomics approach. In total, 913 metabolites were identified and classified into 23 different categories, including phenylpropanoids and flavonoids; among them, 215 (HBG, 177; XQG, 124; and ZQG, 62) metabolites showed differential accumulation in the three comparison groups (HBG/XQG/ZQG versus DHG). A total of 2 unique metabolites, O-caffeoyl maltotriose and myricetin were detected only in DHG samples. When comparing HBG with DHG, there were 109 decreased and 68 increased metabolites; comparing XQG with DHG, there were 88 decreased and 36 increased metabolites; comparing ZQG with DHG, 41 metabolites were decreased, and 21 metabolites were increased. Metabolic pathway enrichment analysis of these differential metabolites showed significant enrichment of the “phenylpropanoid biosynthesis” pathway in all comparison groups. The hierarchical cluster analysis of the differential metabolites of the four groups showed a clear grouping patterns. The relative contents of three phenylpropanoids, four flavonoids, two alkaloids, one anthocyanin, and two other metabolites were significantly different between each comparison group. This study might provide fundamental insight for the isolation and identification of functional compounds from the peels of citrus fruit infected with HLB and for in-depth research on the effect of HLB on the formation of fruits pigment and the development of HLB-resistant citrus varieties.
Article
Full-text available
Background: Fruit coloration is one of the main quality parameters of Citrus fruit primarily determined by genetic factors. The fruit of ordinary sweet orange (Citrus sinensis) displays a pleasant orange tint due to accumulation of carotenoids, representing β,β-xanthophylls more than 80% of the total content. 'Pinalate' is a spontaneous bud mutant, or somatic mutation, derived from sweet orange 'Navelate', characterized by yellow fruits due to elevated proportions of upstream carotenes and reduced β,β-xanthophylls, which suggests a biosynthetic blockage at early steps of the carotenoid pathway. Results: To identify the molecular basis of 'Pinalate' yellow fruit, a complete characterization of carotenoids profile together with transcriptional changes in carotenoid biosynthetic genes were performed in mutant and parental fruits during development and ripening. 'Pinalate' fruit showed a distinctive carotenoid profile at all ripening stages, accumulating phytoene, phytofluene and unusual proportions of 9,15,9'-tri-cis- and 9,9'-di-cis-ζ-carotene, while content of downstream carotenoids was significantly decreased. Transcript levels for most of the carotenoid biosynthetic genes showed no alterations in 'Pinalate'; however, the steady-state level mRNA of ζ-carotene isomerase (Z-ISO), which catalyses the conversion of 9,15,9'-tri-cis- to 9,9'-di-cis-ζ-carotene, was significantly reduced both in 'Pinalate' fruit and leaf tissues. Isolation of the 'Pinalate' Z-ISO genomic sequence identified a new allele with a single nucleotide insertion at the second exon, which generates an alternative splicing site that alters Z-ISO transcripts encoding non-functional enzyme. Moreover, functional assays of citrus Z-ISO in E.coli showed that light is able to enhance a non-enzymatic isomerization of tri-cis to di-cis-ζ-carotene, which is in agreement with the partial rescue of mutant phenotype when 'Pinalate' fruits are highly exposed to light during ripening. Conclusion: A single nucleotide insertion has been identified in 'Pinalate' Z-ISO gene that results in truncated proteins. This causes a bottleneck in the carotenoid pathway with an unbalanced content of carotenes upstream to β,β-xanthophylls in fruit tissues. In chloroplastic tissues, the effects of Z-ISO alteration are mainly manifested as a reduction in total carotenoid content. Taken together, our results indicate that the spontaneous single nucleotide insertion in Z-ISO is the molecular basis of the yellow pigmentation in 'Pinalate' sweet orange and points this isomerase as an essential activity for carotenogenesis in citrus fruits.
Article
Red-peeled huyou has a distinct red peel color due mainly to the presence of red apocarotenoid β-citraurin as well as the increase in amount of total carotenoids. The expression level of carotenoid cleavage dioxygenase 4b1 (CCD4b1) accounted for 99.0% of total transcript abundance of CCD4s in red-peeled huyou peel and was nearly 100 times higher than that in ordinary huyou. β-Citraurin accumulation and peel coloration was mostly favored at 15 °C but strongly inhibited at moderately high temperatures 20 °C and 25 °C. Exogenous ethylene application for 3 d had no obvious effect on β-citraurin accumulation in red-peeled huyou but holding fruit at moderately higher temperatures (20 °C and 25 °C) for 3 d had a significant adverse effect on β-citraurin accumulation. The expression of phytoene synthase 1 (PSY1) and CCD4b1 was higher at 10 °C and 15 °C and significantly lower at 20 °C and 25 °C. The mechanisms governing the accumulation of β-citraurin are discussed.
Article
Flavonoids are plant pigments that provide health benefits for human and animal consumers. Understanding why domesticated crops have altered pigmentation patterns and unraveling the molecular/genetic mechanisms that underlie this will facilitate the breeding of new (healthier) varieties. We present an overview of changes in flavonoid pigmentation patterns that have occurred during crop domestication and, where possible, link them to the molecular changes that brought about the new phenotypes. We consider species that lost flavonoid pigmentation in the edible part of the plant at some point during domestication (like cereals). We also consider the converse situation, for example eggplant (aubergine), which instead gained strong anthocyanin accumulation in the skin of the fruit during domestication, and some varieties of citrus and apple that acquired anthocyanins in the fruit flesh. Interestingly, the genes responsible for such changes are sometimes closely linked to, or have pleiotropic effects on, important domestication genes, suggesting accidental and perhaps inevitable changes of anthocyanin patterning during domestication. In other cases, flavonoid pigmentation patterns in domesticated crops are the result of cultural preferences, with examples being found in varieties of citrus, barley, wheat, and maize. Finally, and more recently, in some species, anthocyanins seem to have been the direct target of selection in a second wave of domestication that followed the introduction of industrial food processing.
Article
Full-text available
Key message Complementation of the “Micro-Tom” tomato tangerine mutant with a Citrus CRTISO allele restores the wild-type fruit carotenoid profile, indicating that the Citrus allele encodes an authentic functional carotenoid isomerase. Abstract Citrus fruits are rich in carotenoids; the genus offers a large diversity in composition, yet to be fully explored to improve fruit nutritional quality. As perennial tree species, Citrus lack the resources for functional genetic studies, requiring the use of model plant systems. Here, we used the “Micro-Tom” (MT) tomato carrying the tangerine mutation (t), deficient for the carotenoid isomerase (CRTISO) gene, to functionally characterize the homologous C. sinensis genes. We identified four putative loci in the C. sinensis genome, named CsCRTISO, CsCRTISO-Like 1, CsCRTISO-Like 2, and CsCRTISO-Like 2B, with the latter as a presumed duplication of CRTISO-Like 2. In general, all the Citrus paralogs showed less expression specialization than the tomato ones, with CsCRTISO being the most expressed gene in all tissues analyzed. MT-t plants were successfully complemented with the CsCRTISO, and fruits showed a carotenoid profile similar to the control, indicating that the Citrus allele indeed encodes an authentic functional carotenoid isomerase and that the signal peptide is functional in tomato. MT was silenced using an inverted repeat of a fragment from the Citrus CRTISO resulting in a stronger phenotype than MT-t. MT-t and MT silenced for CRTISO presented an overall decrease in transcript accumulation of all genes from the biosynthesis pathway. The expression of the Citrus CRTISO gene is able to restore the biosynthesis of carotenoids with the appropriate regulation in MT-t. The decrease in transcript accumulation in MT-t and MT-CRTISO-suppressed lines reinforces previous suggestions that transcriptional regulation of the carotenoid biosynthesis involves regulatory loops by intermediate products.
Article
The citrus family (Rutaceae) is a very complex and diverse source of carotenoids. Carotenoid profile and content varies greatly among different species, cultivars and even fruit tissues (e.g., flavedo and juice sacs). In Uruguay, the Citrus Breeding Program is focused on obtaining good quality seedless mandarin cultivars for the fresh market. One of the strategies to improve the nutritional value of citrus, is to increase the accumulation of antioxidant compounds in the fruit pulp. In order to characterize the mechanisms of carotenoid accumulation, we analyzed the carotenoid content in the pulp of five mandarin hybrids through their maturation cycle during the year 2017. Additionally, we analyzed the mRNA expression patterns of key enzymes (PSY, βCHX) of the carotenoid biosynthesis pathway in different maturity stages: immature green (IG), mature green (MG), color break (B), mature (M). Taken together, these results allowed the identification of genotypes that have the potential to accumulate high levels of carotenoids in the pulp and, therefore, are good candidates for genetic engineering of the carotenoid biosynthetic pathway.
Article
Full-text available
Citrus is an economically important fruit crop widely growing worldwide. However, citrus production largely depends on natural hybrid selection and bud sport mutation. Unique botanical features including long juvenility, polyembryony, and QTL that controls major agronomic traits can hinder the development of superior variety by conventional breeding. Diverse factors including drastic changes of citrus production environment due to global warming and changes in market trends require systematic molecular breeding program for early selection of elite candidates with target traits, sustainable production of high quality fruits, cultivar diversification, and cost-effective breeding. Since the construction of the first genetic linkage map using isozymes, citrus scientists have constructed linkage maps using various DNA-based markers and developed molecular markers related to biotic and abiotic stresses, polyembryony, fruit coloration, seedlessness, male sterility, acidless, morphology, fruit quality, seed number, yield, early fruit setting traits, and QTL mapping on genetic maps. Genes closely related to CTV resistance and flesh color have been cloned. SSR markers for identifying zygotic and nucellar individuals will contribute to cost-effective breeding. The two high quality cit rus reference genomes recently released are being efficiently used for genomics-based molecular breeding such as construction of reference linkage/physical maps and comparative genome mapping. In the near future, the development of DNA molecular markers tightly linked to various agronomic traits and the cloning of useful and/or variant genes will be accelerated through comparative genome analysis using citrus core collection and genome-wide approaches such as genotyping-by-sequencing and genome wide association study.
Article
Full-text available
Carotenoids are abundant in citrus fruits and vary among cultivars and species. In the present study, high performance liquid chromatography (HPLC) and real-time polymerase chain reaction (PCR) were used to investigate the expression patterns of 23 carotenoid biosynthesis gene family members and their possible relation with carotenoid accumulation in fresh flavedo, juice sacs and leaves of Valencia orange during fruit maturation. Violaxanthin and lutein mainly accumulated in fruit (flavedo and juice sacs) and leaves (young and mature), respectively, accounting for nearly 79 %, 57 %, 53 % and 70 % of corresponding total carotenoids in February. Violaxanthin content quickly began to increase in flavedo in December, but the increase in juice sacs began later in January. In mature leaves, lutein content was three times that in young leaves; α-carotene and β-carotene were also much higher in mature leaves than in flavedo or juice sacs. Generally most of the carotenoid biosynthesis gene members were expressed at higher levels in flavedo than in juice sacs, and the expression of some continued to increase in flavedo during fruit maturation. All CHYB members expressed at high levels and had similar patterns in juice sacs. Interestingly, the capsanthin capsorubin synthase (CCS) members had similar expression levels and patterns in flavedo and juice sacs. Differences in gene expression between leaf and fruit tissues were noted, pointing to some tissue specificity for certain members of the gene families associated with carotenogenesis. The expression patterns of these 23 citrus carotenoid biosynthesis gene members were also compared with their expression patterns in other plants. Taken together, these first-hand expression data will be useful to define the tissue-specific roles of each gene member in accumulation of different carotenoids in citrus leaves and maturing fruits.
Article
Full-text available
Cultivated citrus are selections from, or hybrids of, wild progenitor species whose identities and contributions to citrus domestication remain controversial. Here we sequence and compare citrus genomes—a high-quality reference haploid clementine genome and mandarin, pummelo, sweet-orange and sour-orange genomes—and show that cultivated types derive from two progenitor species. Although cultivated pummelos represent selections from one progenitor species, Citrus maxima, cultivated mandarins are introgressions of C. maxima into the ancestral mandarin species Citrus reticulata. The most widely cultivated citrus, sweet orange, is the offspring of previously admixed individuals, but sour orange is an F1 hybrid of pure C. maxima and C. reticulata parents, thus implying that wild mandarins were part of the early breeding germplasm. A Chinese wild 'mandarin' diverges substantially from C. reticulata, thus suggesting the possibility of other unrecognized wild citrus species. Understanding citrus phylogeny through genome analysis clarifies taxonomic relationships and facilitates sequence-directed genetic improvement.
Article
Full-text available
Genes encoding chalcone synthase (CHS), anthocyanidin synthase (ANS), and UDP-glucose-flavonoid 3-O-glucosyltransferase (UFGT), some of the enzymes of anthocyanin biosynthetic pathway, were assayed in two different experiments using quantitative real-time reverse transcriptase (RT)-PCR, in order to test their transcription levels in the flesh of blood and common orange [Citrus sinensis (L.) Osbeck] fruit, and to investigate their role in anthocyanin accumulation in the same tissue. The first experiment compared a blood orange and a common orange cultivar during seven different fruit maturation stages. This was followed by the test of 11 different genotypes at the end of the winter season. Data collected from the first experiment, over the blood orange cultivar, were statistically analyzed using the Pearson correlation coefficient. Results show that CHS, ANS, and UFGT mRNA transcripts are up- and co-regulated in the blood orange cultivar, whereas they are down-regulated in the common orange cultivar. There is evidence of correspondence between the target genes expression level and the content of the pigment assessed. The second test confirms this correlation and shows that enzyme synthesis levels and pigment accumulation, in plants grown under the same environmental conditions, are dependent on the differences occurring among the genotypes tested. These results suggest that the absence of pigment in the common orange cultivars may be caused by the lack of induction on the structural genes expression. This is the first report on the characterization of the relationships between biosynthetic genes expression and fruit flesh anthocyanin content in blood oranges.
Article
Full-text available
Carotenoids are natural isoprenoid pigments that provide leaves, fruits, vegetables and flowers with distinctive yellow, orange and some reddish colours as well as several aromas in plants. Their bright colours serve as attractants for pollination and seed dispersal. Carotenoids comprise a large family ofC40 polyenes and are synthesised by all photosynthetic organisms, aphids, some bacteria and fungi alike. In animals carotenoid derivatives promote health, improve sexual behaviour and are essential for reproduction. As such, carotenoids are commercially important in agriculture, food, health and the cosmetic industries. In plants, carotenoids are essential components required for photosynthesis, photoprotection and the production of carotenoid-derived phytohormones, including ABA and strigolactone. The carotenoid biosynthetic pathway has been extensively studied in a range of organisms providing an almost complete pathway for carotenogenesis. A new wave in carotenoid biology has revealed implications for epigenetic and metabolic feedback control of carotenogenesis. Developmental and environmental signals can regulate carotenoid gene expression thereby affecting carotenoid accumulation. This review highlights mechanisms controlling (1) the first committed step in phytoene biosynthesis, (2) flux through the branch to synthesis of a- and b-carotenes and (3) metabolic feedback signalling within and between the carotenoid, MEP and ABA pathways.
Article
Full-text available
Anthocyanins are water-soluble pigments found in all plant tissues throughout the plant kingdom. Our under- standing of anthocyanin biosynthesis and its molecular control has greatly improved in the last decade. The adaptive advantages of anthocyanins, especially in non- reproductive tissues, is much less clear. Anthocyanins of- ten appear transiently at specific developmental stages and may be induced by a number of environmental fac- tors including visible and UVB radiation, cold tempera- tures and water stress. The subsequent production and localization of anthocyanins in root, stem and especially leaf tissues may allow the plant to develop resistance to a number of environmental stresses. This article reviews the environmental induction of anthocyanins and their proposed importance in ameliorating environmental stresses induced by visible and UVB radiation, drought and cold temperatures.
Article
Full-text available
Citrus species are known by their high content of phenolic compounds, including a wide range of flavonoids. In plants, these compounds are involved in protection against biotic and abiotic stresses, cell structure, UV protection, attraction of pollinators and seed dispersal. In humans, flavonoid consumption has been related to increasing overall health and fighting some important diseases. The goals of this study were to identify expressed sequence tags (EST) in Citrus sinensis (L.) Osbeck corresponding to genes involved in general phenylpropanoid biosynthesis and the key genes involved in the main flavonoids pathways (flavanones, flavones, flavonols, leucoanthocyanidins, anthocyanins and isoflavonoids). A thorough analysis of all related putative genes from the Citrus EST (CitEST) database revealed several interesting aspects associated to these pathways and brought novel information with promising usefulness for both basic and biotechnological applications.
Article
Full-text available
The cyanidin-3- O - g -glucopyranoside (C-3-G) antioxidant capacity towards reactive oxygen species (ROS)-mediated damages was assessed in tissue and cells submitted to increased oxidative stress. In the isolated ischemic and reperfused rat heart, 10 or 30 w M C-3-G protected from both lipid peroxidation (66.7 and 94% inhibition of malondialdehyde (MDA) generation in 10 and 30 w M C-3-G-reperfused hearts, respectively, in comparison with control reperfused hearts) and energy metabolism impairment (higher ATP concentration in 10 and 30 w M C-3-G-reperfused hearts than in control reperfused hearts). These effects were associated to C-3-G permeation within myocardial cells, as indicated by results obtained in the isolated rat heart perfused for 30 min in the recirculating Langendorff mode under normoxia with 10 and 30 w M C-3-G. Protective effects were exerted, in a dose-dependent manner, by C-3-G also in 2 mM hydrogen peroxide-treated human erythrocytes. With respect to MDA formation, an apparent IC 50 of 5.12 w M was calculated for C-3-G (the polyphenol resveratrol used for comparison showed an apparent IC 50 of 38.43 w M). The general indications are that C-3-G (largely diffused in dietary plants and fruits, such as pigmented oranges very common in the Mediterranean diet) represents a powerful natural antioxidant with beneficial effects in case of increased oxidative stress, and at pharmacological concentrations it is able to decrease tissue damages occurring in myocardial ischemia and reperfusion.
Article
Full-text available
Background: Consumption of 100% orange juice (OJ) has been positively associated with nutrient adequacy and diet quality, with no increased risk of overweight/obesity in children; however, no one has examined these factors in adults. The purpose of this study was to examine the association of 100% OJ consumption with nutrient adequacy, diet quality, and risk factors for metabolic syndrome (MetS) in a nationally representative sample of adults. Methods: Data from adults 19+ years of age (n = 8,861) participating in the National Health and Nutrition Examination Survey 2003-2006 were used. The National Cancer Institute method was used to estimate the usual intake (UI) of 100% OJ consumption, selected nutrients, and food groups. Percentages of the population below the Estimated Average Requirement (EAR) or above the Adequate Intake (AI) were determined. Diet quality was measured by the Healthy Eating Index-2005 (HEI-2005). Covariate adjusted logistic regression was used to determine if consumers had a lower odds ratio of being overweight or obese or having risk factors of MetS or MetS. Results: Usual per capita intake of 100% OJ was 50.3 ml/d. Among consumers (n = 2,310; 23.8%), UI was 210.0 ml/d. Compared to non-consumers, consumers had a higher (p < 0.05) percentage (% ± SE) of the population meeting the EAR for vitamin A (39.7 ± 2.5 vs 54.0 ± 1.2), vitamin C (0.0 ± 0.0 vs 59.0 ± 1.4), folate (5.8 ± 0.7 vs 15.1 ± 0.9), and magnesium (51.6 ± 1.6 vs 63.7 ± 1.2). Consumers were also more likely to be above the AI for potassium (4.1 ± 0.8 vs 1.8 ± 0.2). HEI-2005 was significantly (p < 0.05) higher in consumers (55.0 ± 0.4 vs 49.7 ± 0.3). Consumers also had higher intakes of total fruit, fruit juice, whole fruit, and whole grain. Consumers had a lower (p < 0.05) mean body mass index (27.6 ± 0.2 vs 28.5 ± 0.1), total cholesterol levels (197.6 ± 1.2 vs 200.8 ± 0.75 mg/dL), and low density lipoprotein-cholesterol levels (112.5 ± 1.4 vs 116.7 ± 0.93 mg/dL). Finally, compared to non-consumers of 100% OJ, consumers were 21% less likely to be obese and male consumers were 36% less likely to have MetS. Conclusion: The results suggest that moderate consumption of 100% OJ should be encouraged to help individuals meet the USDA daily recommendation for fruit intake and as a component of a healthy diet.
Article
Full-text available
Oranges are an important nutritional source for human health and have immense economic value. Here we present a comprehensive analysis of the draft genome of sweet orange (Citrus sinensis). The assembled sequence covers 87.3% of the estimated orange genome, which is relatively compact, as 20% is composed of repetitive elements. We predicted 29,445 protein-coding genes, half of which are in the heterozygous state. With additional sequencing of two more citrus species and comparative analyses of seven citrus genomes, we present evidence to suggest that sweet orange originated from a backcross hybrid between pummelo and mandarin. Focused analysis on genes involved in vitamin C metabolism showed that GalUR, encoding the rate-limiting enzyme of the galacturonate pathway, is significantly upregulated in orange fruit, and the recent expansion of this gene family may provide a genomic basis. This draft genome represents a valuable resource for understanding and improving many important citrus traits in the future.
Article
Full-text available
Levan is a commonly used dietary fiber of the fructans group. Its impact on health remains undetermined. This double blind controlled study aimed to investigate the effect of 8 weeks' daily consumption of 500 mL of natural orange juice enriched with 11.25 g of levan compared to the same amount of natural orange juice without levan on weight, gastrointestinal symptoms and metabolic profiles of 48 healthy volunteers. The statistical analyses compared between- and within-group findings at baseline, 4 weeks and study closure. The compared parameters were: weight, blood pressure, blood laboratory tests, daily number of defecations, scores of stool consistency, abdominal pain, bloating, gas, dyspepsia, vomiting and heartburn. Despite a higher fiber level recorded in the study group, there was no significant difference in the effect of the two kinds of juices on the studied parameters. Both juices decreased systolic and diastolic pressures, increased sodium level (within normal range), stool number, and bloating scores, and decreased gas scores. In conclusion, levan itself had no effect on weight, gastrointestinal symptoms or metabolic profile of healthy volunteers. Its possible effect on obese, hypertensive or hyperlipidemic patients should be investigated in further studies.
Article
Full-text available
Caloric beverages may promote weight gain by simultaneously increasing total energy intake and limiting fat oxidation. During moderate intensity exercise, caloric beverage intake depresses fat oxidation by 25% or more. This randomized crossover study describes the impact of having a caloric beverage with a typical meal on fat oxidation under resting conditions. On 2 separate days, healthy normal-weight adolescents (n = 7) and adults (n = 10) consumed the same breakfast with either orange juice or drinking water and sat at rest for 3 h after breakfast. The meal paired with orange juice was 882 kJ (210 kcal) higher than the meal paired with drinking water. Both meals contained the same amount of fat (12 g). For both age groups, both meals resulted in a net positive energy balance 150 min after breakfast. Resting fat oxidation 150 min after breakfast was significantly lower after breakfast with orange juice, however. The results suggest that, independent of a state of energy excess, when individuals have a caloric beverage instead of drinking water with a meal, they are less likely to oxidize the amount of fat consumed in the meal before their next meal.
Article
Full-text available
Genes involved in flavonoid and stilbene biosynthesis were isolated from grape (Vitis vinifera L.). Clones coding for phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydoxylase (F3H), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin dioxygenase (LDOX) and UDP glucose:flavonoid 3-O-glucosyl transferase (UFGT), were isolated by screening a cDNA library, obtained from mRNA from seedlings grown in light for 48 h using snapdragon (Antirrhinum majus) and maize heterologous probes. A cDNA clone coding for stilbene synthase (StSy) was isolated by probing the library with a specific oligonucleotide. These clones were sequenced and when the putative products were compared to the published amino acid sequence for corresponding enzymes, the percentages of similarity ranged from 65% (UFGT) to 90% (CHS and PAL). The analysis of the genomic organization and expression of these genes in response to light shows that PAL and StSy genes belong to large multigene families, while the others are present in one to four copies per haploid genome. The steady-state level of mRNAs encoded by the flavonoid biosynthetic genes as determined in young seedlings is coordinately induced by light, except for PAL and StSy, which appear to be constitutively expressed.
Article
Full-text available
Plant carotenoids are a family of pigments that participate in light harvesting and are essential for photoprotection against excess light. Furthermore, they act as precursors for the production of apocarotenoid hormones such as abscisic acid and strigolactones. In this review, we summarize the current knowledge on the genes and enzymes of the carotenoid biosynthetic pathway (which is now almost completely elucidated) and on the regulation of carotenoid biosynthesis at both transcriptional and post-transcriptional levels. We also discuss the relevance of Arabidopsis as a model system for the study of carotenogenesis and how metabolic engineering approaches in this plant have taught important lessons for carotenoid biotechnology.
Article
Full-text available
Traditionally, Sicilian blood oranges (Citrus sinensis) have been associated with cardiovascular health, and consumption has been shown to prevent obesity in mice fed a high-fat diet. Despite increasing consumer interest in these health-promoting attributes, production of blood oranges remains unreliable due largely to a dependency on cold for full color formation. We show that Sicilian blood orange arose by insertion of a Copia-like retrotransposon adjacent to a gene encoding Ruby, a MYB transcriptional activator of anthocyanin production. The retrotransposon controls Ruby expression, and cold dependency reflects the induction of the retroelement by stress. A blood orange of Chinese origin results from an independent insertion of a similar retrotransposon, and color formation in its fruit is also cold dependent. Our results suggest that transposition and recombination of retroelements are likely important sources of variation in Citrus.
Article
Full-text available
Abstract Members of the MYB and MYC family regulate the biosynthesis of phenylpropanoids in several plant species. Two sequences, called CsMYB8 and CsMYC2, were identified from Citrus sinensis, and both the cDNA and the genomic clones were isolated and characterized from the flesh of common and blood oranges. Analysis by real-time polymerase chain reaction showed that the expression pattern of CsMYC2 is generally higher in rind than in flesh and in blood oranges than in common ones. In contrast, no significant difference in expression was observed for CsMYB8. The expression pattern of the structural genes chalcone synthase, anthocyanidin synthase, and UDP-glucose–flavonoid 3-O-glucosyltransferase, which code for three enzymes involved in the anthocyanin biosynthetic pathway, was also analyzed and correlated with CsMYC2, in flesh, rind, and leaf of the common and blood oranges, and in leaf of Citrus limon cultivars (characterized by anthocyanin absence or variable content). Surprisingly, CsMYC2 is highly expressed in the leaf and expression is correlated with UFGT expression in this organ. These results suggest that CsMYC2 is involved in the regulation of the flavonoid biosynthetic pathway in Citrus.
Article
Full-text available
The flavonoid pathway produces a diverse array of plant compounds with functions in UV protection, as antioxidants, pigments, auxin transport regulators, defence compounds against pathogens and during signalling in symbiosis. This review highlights some of the known function of flavonoids in the rhizosphere, in particular for the interaction of roots with microorganisms. Depending on their structure, flavonoids have been shown to stimulate or inhibit rhizobial nod gene expression, cause chemoattraction of rhizobia towards the root, inhibit root pathogens, stimulate mycorrhizal spore germination and hyphal branching, mediate allelopathic interactions between plants, affect quorum sensing, and chelate soil nutrients. Therefore, the manipulation of the flavonoid pathway to synthesize specifically certain products has been suggested as an avenue to improve root-rhizosphere interactions. Possible strategies to alter flavonoid exudation to the rhizosphere are discussed. Possible challenges in that endeavour include limited knowledge of the mechanisms that regulate flavonoid transport and exudation, unforeseen effects of altering parts of the flavonoid synthesis pathway on fluxes elsewhere in the pathway, spatial heterogeneity of flavonoid exudation along the root, as well as alteration of flavonoid products by microorganisms in the soil. In addition, the overlapping functions of many flavonoids as stimulators of functions in one organism and inhibitors of another suggests caution in attempts to manipulate flavonoid rhizosphere signals.
Chapter
This book is intended to provide consolidated information on citrus breeding in the era of biotechnology, which is likely to hasten the pace of variety development aimed at resolving the problems faced by grove owners growing currently available cultivars. The subjects covered are focused on citrus while providing information equally useful to the breeders of other tree crops. It will also help students of genetic and breeding identify appropriate applications of biotechnology in citrus breeding. While providing information on future avenues, it also reviews the past progress and achievements ensuring continuity of the subject. Several chapters include protocols for novel techniques that should facilitate their broader application by citrus breeders.
Chapter
It is commonly accepted that cancer formation can be prevented by the consumption of certain foods; thus flavonoids in Citrus fruits and juices are among the most prominent anticancer agents. From a viewpoint of health-promotion by dietary habits, cancer preventative activity in the Citrus juices is more important than that found in their inedible parts. However, few studies have focused on the biological activities in Citrus juices, possibly because the measurable activities in juices tend to be hindered by the more abundant substances, such as sugars. In order to eliminate the masking, we prepared the readily extractable fractions of Citrus juices by adsorbing on porous polymer resin, and successive elution from the resin with ethanol and acetone. Among 34 Citrus juices examined, King (C. nobilis) exhibited potent differentiation-inducing activity toward HL-60 leukemia cells, and the active principles were identified as four polymethoxyflavones. (C) 2004 American Chemical Society.
Article
One of the major anthocyanins of blood orange juice, previously designated as cyanidin-3-glucoside-acetate or cyanidin-3-rhamnoside, was extracted and purified by semi-preparative HPLC. The structure of the pigment was elucidated by HPLC-Mass Spectrometry and 1H NMR spectroscopy to be cyanidin-3-(6″-malonyl)-β-glucoside.
Article
Flavonoid-derived plant natural products have long been known to function as floral pigments for the attraction of insect pollinators, as signal molecules for beneficial microorganisms in the rhizosphere, and as antimicrobial defense compounds. New functions for flavonoid compounds continue to be found, particularly in plant-microorganism signaling, and there has been an explosion of interest in flavonoids and isoflavonoids as health-promoting components of the human diet. The flavonoid and isoflavonoid pathways are probably the best characterized natural product pathway in plants, and are therefore excellent targets for metabolic engineering. Manipulation of flavonoid biosynthesis can be approached via several strategies, including sense or antisense manipulation of pathway genes, modification of the expression of regulatory genes, or generation of novel enzymatic specificities by ra-tional approaches based on emerging protein structure data. In addition, activation tagging provides a novel approach for the discovery of uncharacterized structural and regulatory genes of flavonoid biosynthesis.
Article
Citrus is a complex source of carotenoids with the largest number of carotenoids found in any fruit. Carotenoid concentration and composition vary greatly among citrus varieties. Satsuma mandarin (Citrus unshiu Marc.) predominantly accumulates β-cryptoxanthin in the juice sacs. Valencia orange (Citrus sinensis Osbeck) predominantly accumulates violaxanthin isomers in the juice sacs. Lisbon lemon (Citrus limon Burm.f.) accumulates low level of carotenoids in the juice sacs. To elucidate the carotenoid accumulation in citrus fruit maturation, the expression of genes related to carotenoid biosynthesis and catabolism was investigated in the three citrus varieties exhibited different carotenoid profile. The results showed that the carotenoid accumulation during citrus fruit maturation is highly regulated by the coordination of the expression for the genes related to carotenoid biosynthesis and catabolism in both flavedo and juice sacs. 'Tamami' is a hybrid between 'Kiyomi' tangor (Citrus unshiu Marc. × Citrus sinensis Osbeck) and 'Wilking' mandarin (Citrus nobilis Lour. × Citrus deliciosa Ten.). To elucidate the mechanism of the accumulation of β-cryptoxanthin in 'Tamami', a variety accumulating higher β-cryptoxanthin than Satsuma mandarin, the expression of genes related to carotenoid biosynthesis and catabolism was investigated in the juice sacs of 'Tamami'. The results showed that the mechanism of β-cryptoxanthin accumulation in 'Tamami' was similar to that in Satsuma mandarin. Furthermore, in the recent studies, possible factors, which regulate carotenoid concentration and composition in citrus juice sacs were investigated in vitro.
Article
The affinity relationships of 43 biotypes of cultivated Citrus-close relatives, interspecific and intergeneric hybrids, and clones of unknown origin-were studied to develop information for use in citrus breeding experiments. Intraspecific affinity was very high (87 to 98) in four of six cultivated Citrus species (C. aurantium, C. grandis, C. limon, and C. paradisi) but lower in C. reticulata (45 to 58) and in C. sinensis (37). Among Citrus species and relatives, the affinity pattern showed two main groups in Citrus and a third group consisting of Eremocitrus glauca and Microcitrus species. The larger Citrus group included five species (C. aurantium, C. grandis, C. paradisi, C. reticulata, and C. sinensis) and a smaller group of three (C. aurantifolia, C. limon, and C. medica). The charcteristics of C. grandis were dominant in interspecific hybrids. In hybrids of cultivated Citrus species and wild relatives, the characteristics of the latter were strongly dominant with one exception. The affinities of clones of unknown origin indicated probable hybrid origins of diverse genetic backgrounds. Comparisons of the data on the study clones were made with the major authoritative speculations on their derivations. Citrus grandis, C. medica, and C. reticulata are proposed as true biological species. Citrus aurantifolia, C. aurantium, C. limon, C. paradisi, and C. sinensis are proposed as unique, apomictically perpetuated biotypes of probable hybrid origin. A nonmetric multidimensional scaling solution is presented to support, in part, the proposed systematic relationships. Inadequate sampling of the variation present in populations and a lack of appreciation of the effects of facultative apomixis on population samples and its relationship to genetic heterozygosity in Citrus have been the major obstacles in past efforts to produce an objective Citrus taxonomy.
Article
In this study we isolated the partial cDNA clone of three enzymes active in the late steps of anthocyanins biosynthetic pathway such as DFR, ANS and UFGT from Citrus sinensis (L) Osbeck. The predicted aminoacids sequences shared very high identity values ranging from 77 % for DFR (Pyrus communis, Malus domestica), to 86 % for ANS (Vitis vinifera) with homologous available protein sequences. Only the UFGT sequence showed lower identity value (59 %), but this finding is in accordance with data obtained for other enzymes belonging to the plant glucosyl transferase superfamily. The expression of CHS, CHI, F3OH, DFR, ANS and UFGT was also investigated in both coloured and uncoloured oranges juice vesicles. Transcripts encoding the enzymes involved in the earlier reactions have been detected in either blood and blonde oranges by RT-PCR. Conversely, considerable difference emerged in the case of the later gene ufgt which was totally unexpressed in blonde oranges juice vesicles probably determining the lack of anthocyanins production in all blonde orange cultivars analysed.
Article
The health benefit of a diet rich in fruits and vegetables could be attributed to the presence of a large diversity of phytochemicals, including carotenoids. Bioactivities of carotenoids greatly depend on their bioavailability that could be modulated by the presence of other dietary constituents. Because citrus juices contain diverse antioxidant phytochemicals, the effects of flavonoids and ascorbic acid on intestinal carotenoid uptake were investigated. Experiments were conducted by using a Caco-2 cell monolayer exposed to micelles enriched in β-cryptoxanthin (b-CX, 5 μM) and β-carotene (b-C, 5 μM) in the presence of hesperetin (HES, 250 μM), hesperidin (HES-G, 250 μM), naringenin (NGN, 250 μM), acid ascorbic (AA, 50 μM) and iron. At 5 h or 24 h incubation, HES-G and HES significantly increased b-CX and b-C uptake by 1.7- and 1.6-fold, respectively (p < 0.05). Interestingly, AA was shown to eliminate the enhancing effect of HES-G by decreasing significantly the cellular uptake of carotenoids from 48.2 to 39.8% after 5 h incubation (p < 0.05). Iron decreased the carotenoid uptake, while HES-G in the presence of iron restored it, suggesting that the enhancing effect of HES-G on carotenoid uptake could be attributed to its iron-chelating activity.
Article
Due to their theoretically identical genetic background, citrus callus and other plant tissues may share some mechanisms in the regulation of carotenogenesis. Thus, in order to gain further information on light regulation of carotenoids biosynthesis in citrus, the carotenoids and expression profiles of carotenogenesis in calluses of four citrus genotypes treated with light or dark were investigated. As a response to white light, results showed that carotenoids biosynthesis in callus of Red Marsh grapefruit (Citrus paradisi Macf.) was hampered, whereas callus of Tarocco blood orange (C. sinensis (L.) Osbeck) was sensitive to light by accumulating over 55% more carotenoids on average. Among the detected carotenoids, the biosynthesis of carotenes seemed to be more sensitive than that of xanthophylls. Expression profiles of eight carotenogenesis genes encoding phytoene synthase (PSY), phytoene desaturase (PDS), ζ-carotene desaturase (ZDS), carotenoids isomerase (CRTISO) etc. were investigated. Results revealed that PSY was up regulated in calluses of two sweet oranges, and down regulated in callus of Murcott tangor (C. reticulata × C. sinensis). Biochemical data in the three genotypes emphasized the PSY as a rate-limiting gene in the carotenogenesis. However, in the callus of Red Marsh grapefruit, PDS and ZDS might be the rate-limiting genes, and their transcripts were apparently inhibited by light, led to significant decreases in contents of β-carotene and total carotenoids irrelevant to transcription levels of PSY. Expression of CRTISO was light-induced, especially in the callus of Murcott tangor, and increased by nearly 12-fold. In conclusion, light regulates the expression of several carotenogenesis genes in citrus callus, but may not necessarily result in significant changes in carotenoids production.
Article
Purpose of review: Citrus flavonoids are polyphenolic compounds with powerful biological properties. This review aims to summarize recent advances towards understanding the ability of citrus flavonoids to regulate lipid metabolism and other metabolic parameters relevant to the metabolic syndrome, type 2 diabetes and cardiovascular disease. Recent findings: Citrus flavonoids, including naringenin, hesperidin, nobiletin and tangeretin, have emerged as promising therapeutic agents for the treatment of metabolic dysregulation. Epidemiological studies report that intake of citrus flavonoid-containing foods attenuates cardiovascular diseases. Experimental and a limited number of clinical studies reveal lipid-lowering, insulin-sensitizing, antihypertensive and anti-inflammatory properties. In animal models, citrus flavonoid supplements prevent hepatic steatosis, dyslipidemia and insulin sensitivity primarily through inhibition of hepatic fatty acid synthesis and increased fatty acid oxidation. Citrus flavonoids blunt the inflammatory response in metabolically important tissues including liver, adipose tissue, kidney and the aorta. The mechanisms underlying flavonoid-induced metabolic regulation have not been completely established. In mouse models, citrus flavonoids show marked suppression of atherogenesis through improved metabolic parameters and also through direct impact on the vessel wall. Summary: These recent studies suggest an important role of citrus flavonoids in the treatment of dyslipidemia, insulin resistance, hepatic steatosis, obesity and atherosclerosis. The favorable outcomes are achieved through multiple mechanisms. Human studies focussed on dose, bioavailability, efficacy and safety are required to propel the use of these promising therapeutic agents into the clinical arena.
Article
The effects of organic farming, pasteurisation and addition of β-cyclodextrin on the content of vitamin C, colour, carotenoids and antioxidant capacity of orange juices were studied. After pasteurisation at 98 °C (20 s) and subsequently storage along 145 days at room temperature (20–25 °C), the loss of vitamin C content was around 30%. The effects of the thermal process on carotenoid were clearly observed in lutein (loss of 16% for organic and traditional 8%) and especially β-cryptoxanthin (loss of 30%). The colour changes were noticeable after the pasteurisation of orange juice and subsequent storage, with significant decreases being observed in lightness and the coordinate a*, while increases were found for coordinates b*, Hue* and chroma. The antioxidant capacity was 0.075 ± 0.01 and 0.053 ± 0.01 mMT mL−1 for organic and conventional, respectively, with losses around 40% being found at the end of the storage period. The addition of β-cyclodextrin caused no significant effects on the parameters under analysis. These data showed that strong thermal treatments, such as pasteurisation, adversely affect the nutritional and sensory quality of orange juices.
Article
A growing body of evidence indicates that phenylpropanoid and flavonoid metabolism is catalyzed, not by free-floating ‘soluble’ enzymes, but via one or more membrane-associated multienzyme complexes. This type of macromolecular organization has important implications for the overall efficiency, specificity, and regulation of these pathways. Classical biochemical studies of phenylpropanoid and flavonoid metabolism have laid a solid foundation for this model, providing evidence of the channeling of intermediates between enzyme active sites and co-localization of enzymes in cell membranes. This work is now being extended using transgenic plants to determine how the partitioning of metabolites within these pathways is controlled, as well as applying sensitive methods to define specific interactions among the individual enzymes. Information from these studies promises to provide new insights into the structuring of biosynthetic pathways within cells, which should lead to more effective means for engineering the production of plant metabolites with nutritional and agronomic importance.
Chapter
Introduction Origin Evolution of Grapefruit Cultivars Breeding Grapefruit and Hybrid Cultivars Summary Literature Cited
Article
Two genes active in the early steps of flavonoid biosynthesis were isolated from a citrus cDNA library, and their expression patterns were analyzed during citrus (Citrus unshiu Marc.) fruit development in relation to flavonoid contents. The respective cDNA clones from chalcone isomerase (CHI, CitCHI) and flavanone 3-hydroxylase (F3H, CitF3H) are 931 and 1360 bp long, encoding 222 and 362 amino acid residues. CitCHI seems to be a single-copy gene, whereas a few CitF3H-related sequences are present in the citrus genome. Messenger RNA levels of the flavonoid biosynthetic genes CitCHI and CitF3H and two previously isolated chalcone synthases (CHS, CitCHS1, and CitCHS2) were analyzed in various tissues during fruit development. Transcript levels for CitCHS1, CitCHS2, CitCHI, and CitF3H were generally high in young tissues and low in senescent tissues. Flavonoid changes were analyzed in relation to gene expression. High flavonoid contents were found in young tissues. The high expression of flavonoid biosynthetic genes and high accumulation of flavonoids in young fruits suggest that flavonoids are synthesized in the early developmental stage.
Article
l-phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) is generally recognised as a marker of environmental stress in different plant tissues. To investigate the involvement of PAL in the response of citrus fruits to cold temperature, changes in the abundance of PAL mRNA and PAL activity were examined in flavedo tissue of the chilling-sensitive Fortune cultivar (Citrus clementina Hort. ex Tanaka×Citrus reticulata, Blanco). A cDNA library was constructed from flavedo tissue of chilling-stressed fruits and screened with a 660 bp PAL probe, obtained by polymerase chain reaction using oligonucleotides derived from conserved sequence regions. Two full-length cDNA clones (FPAL1 and FPAL2) were isolated, and the deduced amino acid sequences showed a 75–85% similarity with PAL genes from other plant species. A comparative analysis of the changes in PAL activity and PAL mRNA levels was conducted in fruits stored at chilling (2°C) and non-chilling (12°C) temperatures. Northern blot analyses, using both FPAL1 and FPAL2 cDNAs as probes, recognised a single mRNA that accumulated in fruits exposed to 2°C prior to the appearance of physical chilling symptoms and the accompanying increase in PAL activity. Once symptoms were obvious, accumulation of PAL transcript and PAL activity were restricted to the tissue in and around the necrotic regions. However, exposure to a low non-chilling temperature produced an early, moderate and transient increase in PAL mRNA levels and PAL activity that declined after 1 day. This transient induction of both PAL gene expression and activity could be part of a rapid adaptive response of the tissue to low temperatures. Interestingly, a rapid and sustained accumulation of PAL transcript occurred in the leaves and roots of citrus plants exposed to a low temperature in the absence of any detectable chilling-induced damage.
Article
Citrus phylogeny was investigated using RAPD, SCAR and cpDNA markers. The genotypes analyzed included 36 accessions belonging to Citrus together with 1 accession from each of the related genera Poncirus, Fortunella, Microcitrus and Eremocitrus. Phylogenetic analysis with 262 RAPDs and 14 SCARs indicated that Fortunella is phylogenetically close to Citrus while the other three related genera are distant from Citrus and from each other. Within Citrus, the separation into two subgenera, Citrus and Papeda, designated by Swingle, was clearly observed except for C. celebica and C. indica. Almost all the accessions belonging to subgenus Citrus fell into three clusters, each including 1 genotype that was considered to be a true species. Different phylogenetic relationships were revealed with cpDNA data. Citrus genotypes were separated into subgenera Archicitrus and Metacitrus, as proposed by Tanaka, while the division of subgenera Citrus and Papeda disappeared. C. medica and C. indica were quite distant from other citrus as well from related genera. C. ichangensis appeared to be the ancestor of the mandarin cluster, including C. tachibana. Lemon and Palestine sweet lime were clustered into the Pummelo cluster led by C. latipes. C. aurantifolia was located in the Micrantha cluster. Furthermore, genetic origin was studied on 17 cultivated citrus genotypes by the same molecular markers, and a hybrid origin was hypothesized for all the tested genotypes. The assumptions are discussed with respect to previous studies; similar results were obtained for the origin of orange and grapefruit. Hybrids of citron and sour orange were assumed for lemon, Palestine sweet lime, bergamot and Volkamer lemon, while a citron × mandarin hybrid was assumed for Rangpur lime and Rough lemon. For Mexican lime our molecular data indicated C. micrantha to be the female parent and C. medica as the male one.
Article
Anthocyanins are a group of natural occurring pigments responsible for the red-blue colour of many fruits and vegetables. Anthocyanins are of interest for two reasons because they cannot only be used in the technological field as natural colorants but also have important implications in the field of human health. Numerous studies indicate the potential effect that this family of flavonoids may have in reducing the incidence of cardiovascular disease, cancer, hyperlipidemias and other chronic diseases through the intake of anthocyanin-rich foods. This review examines existing literature in this area: from plant content and distribution to health implications, including the effect of agronomic and genetic modifications on the anthocyanin content of plants as well as other biotechnological factors and food processing. The bioavailability, metabolism, bioactivity, and epidemiology of anthocyanins will also be reviewed.
Article
Eight carotenoids, such as phytoene, α-carotene, violaxanthin, etc., synthesized in citrus callus of 31 genotypes were identified and determined. Though varied with genotypes, the carotenoids composition of callus derived from a certain genotype was stable, while carotenoids contents altered between sub-cultures. Some specific carotenoids were produced in calluses of limited genotypes: β-citraurin was only synthesized in calluses of Nianju tangerine (Citrus reticulata Blanco) and Page tangelo (C. reticulata×C. paradisi); while 9-Z-violaxanthin was only detected in Nianju tangerine and Skaggs Bonanza navel orange (C. sinensis L. Osbeck). Notably, the only carotenoid detected in calluses of Natsudaidai (C. aurantium L.) and other two sweet oranges (C. sinensis L. Osbeck) was phytoene. It implied that citrus calluses could be employed to produce specific carotenoids in the future. To further elucidate the characters of callus carotenoids profile, comparisons of carotenoids profiles was made among calluses, fruit tissues and leaves of four selected citrus genotypes. Results showed that lycopene was not detected in leaves and calluses; nevertheless, both citrus fruits and calluses accumulated phytoene, whereas leaves did not except those of Cara Cara navel orange. It is postulated that citrus callus featured its carotenoids profile different from fruit tissues and leaves. In conclusion, the advantages of using citrus callus as an alternative model research system in understanding the regulation of carotenogenesis have been discussed. KeywordsCitrus callus–Carotenoids profile–Fruit tissues–Leaves
Article
Novel expressed and genomic members in sweet orange (Citrus sinensis [L.] Osbeck) carotenoid biosynthesis gene families have been identified through mining of an expressed sequence tags (ESTs) database and hybridization with a bacterial artificial chromosome (BAC) library. These new expressed members included one phytoene synthase (PSY), one phytoene desaturase (PDS), ten zeta-carotene desaturases (ZDS), one lycopene beta-cyclase (LCYB), one lycopene epsilon-cyclase (LCYE), four carotenoid beta-ring hydroxylases (CHYB), and one capsanthin/capsorubin synthase (CCS). Most unigenes with multiple ESTs, including the ones containing the known genes and these new members, were heterozygous, in which putative single nucleotide polymorphisms distinguished two alleles. According to digital gene expression profiling, fruit was the primary tissue where at least one member of each gene family was specifically or highly expressed. Digital expression levels varied among the members and tissues. According to Southern hybridization of the identified BAC clones, genomic members of the families were either clustered in a single BAC contig or distributed in several different contigs. PSY has four members in one contig, PDS two in one, ZDS 12 in three, LCYB 11 in three, LCYE three in two, CHYB eight in one, and CCS 14 in four, respectively. The number of the genomic members in most families tended to be more than that of the expressed members, suggesting that some genomic members may not be expressed or structurally functional. These new carotenoid gene members, along with much first-hand genomic information, can be used further for functional genomics and genetic mapping. KeywordsGene duplication-Transcriptional analysis-Genomic organization
Article
Unlabelled: The main objective of this work was to investigate the effect of storage temperature (4 and 20 °C) on carotenoid accumulation and on the expression levels of seven carotenoid biosynthetic genes (Psy, Pds, Zds, Lcyb, Lcye, Hyb and Zep) in postharvest 'Cara Cara' navel orange (C. sinensis Osbeck) fruits. Storage at 20 °C rapidly increased the carotenoid content in the peel, whereas the content remained unchanged in the pulp before 35 days of storage. By contrast, storage at 4 °C maintained the carotenoid content in the peel before 35 days of storage, after which it slightly increased as time progressed. However, the content in the pulp gradually increased over the entire storage period. In the peel, the gene expressions of Psy and Lcyb were up-regulated at 20 °C but remained unchanged at 4 °C. In addition, the gene expressions of Zds, Hyb, and Zep were repressed at both temperatures before the early storage, followed by a rapid increase only at 20 °C. Then the expressions remained constant level at both temperatures, with the expression level at 20 °C higher than that at 4 °C. Low temperature (4 °C) apparently induced the expression of all the test carotenoid biosynthetic genes in the pulp, in contrast to the nearly stable level at 20 °C. Our present study suggests that the carotenoid biosynthesis in postharvest 'Cara Cara' fruits is transcriptionally regulated, and storage temperature affects the carotenoid accumulation and gene expression in a tissue-dependent manner. Key message: Temperature could affect the carotenoid biosynthesis in postharvest 'Cara Cara' fruits in a tissue-dependent manner. The carotenoid biosynthesis in postharvest 'Cara Cara' fruits was transcriptionally regulated by correlated genes.
Article
An integrative analysis of transcriptome and proteome was performed to identify differential genes/proteins of a red-flesh sweet orange Cara Cara in comparison with a common cultivar Newhall at ripening stages. At the transcript level, gene expression was measured with Massively Parallel Signature Sequencing (MPSS), and 629 genes of these two sweet orange cultivars differed by two fold or more (FDR<0.001). At the protein level, a combination of 2DE and MALDI-TOF-TOF MS identified 48 protein spots differed in relative abundance (P<0.05). The data obtained from comparing transcriptome with proteome showed a poor correlation, suggesting the necessity to integrate both transcriptomic and proteomic approaches in order to get a comprehensive molecular characterization. Function analysis of the differential genes/proteins revealed that a set of candidates was associated with carotenoid biosynthesis and the regulation. Overall, some intriguing genes/proteins were previously unrecognized related with the formation of red-flesh trait, which provided new insights into molecular processes regulating lycopene accumulation in a red-flesh sweet orange. In addition, some genes/proteins were found to be different in expression patterns between the Cara Cara and another red-flesh sweet orange Hong Anliu, and their potential roles were further discussed in the present study.
Article
Oxidative and inflammatory stresses are involved in the pathogenesis of atherosclerosis. The consumption of fruit and vegetables is associated with improved health and reduced cardiovascular risk. Red oranges have a high content of antioxidant and antiinflammatory substances, but there is a paucity of data concerning their effects on cardiovascular biomarkers in subjects with increased cardiovascular risk. We investigated the effect of red orange juice intake on endothelial function, oxidative stress, and markers of inflammation in subjects with increased cardiovascular risk. Nineteen nondiabetic subjects with increased cardiovascular risk (aged 27-56 y) were included in a randomized, placebo-controlled, single-blind crossover study and compared with 12 healthy, nonobese control subjects. In 2 periods of 7 d each with a 3-d interval, each participant alternatively received 500 mL red orange juice/d and 500 mL placebo/d in a random sequence. All measurements were performed in the morning after overnight fasting. Endothelial function, which was measured as flow-mediated dilation, significantly improved and was normalized (5.7% compared with 7.9%; P < 0.005) after 1 wk of red orange juice consumption. Similarly, concentrations of high-sensitivity C-reactive protein, IL-6, and TNF-α significantly decreased (P < 0.001). Red orange juice had no significant effect on nitric oxide plasma concentrations. A 7-d consumption of red orange juice ameliorates endothelial function and reduces inflammation in nondiabetic subjects with increased cardiovascular risk. This trial was registered at biomedcentral.com as ISRCTN39987296.
Article
Lutein, zeaxanthin, β-cryptoxanthin, α-carotene and β-carotene have been determined in samples of Brazilian orange juice (Citrus sinensis). The concentrations found in factory-produced concentrates have been compared with those obtained on the Brazilian retail market and with authentic hand-squeezed juices. The analyses of the latter enabled a comparison of varieties to be made. A concentration range of 0.11–1.21 mg litre−1 was determined for total carotenoids with β-carotene, the most important source of Vitamin A, being found in the highest concentration in the Pera variety followed by Valência, Natal, Lima and Baı́a varieties. The total carotenoids present in samples of frozen concentrated orange juice (FCOJ) obtained from factories ranged from 0.26–0.48 mg litre−1, while retail samples of this product contained slightly more (0.46–0.81 mg litre−1). Frozen concentrated orange pulp-wash presented much lower concentrations, ranging from 0.04 to 0.08 mg litre−1 of total carotenoids. Fourteen samples of retail freshly-squeezed orange juice contained carotenoids ranging from 0.04 to 0.55 mg litre−1, with only one sample out of the range found for authentic samples. This could be due to the addition of pulp-wash to this sample, in which undeclared sorbic acid was also detected.
Article
The influence of temperature, pH, the presence or absence of light, the presence or absence of oxygen and the presence or absence of tannic acid on the colour stability of anthocyanins from crude extract of Isabel grapes (Vitis labrusca L.) in food and model systems was studied. The spectrophotometric results (Δλ, ΔA) revealed interaction between the anthocyanins of the crude extract and tannic acid, suggesting copigmentation. In a model system, temperature, pH, the presence or absence of light, the presence or absence of oxygen and the presence or absence of tannic acid, significantly affected the half-life time of anthocyanins. The long half-time of the anthocyanins from Isabel grapes in a yoghurt model system indicates that these pigments are relatively stable in this food. In a rehydrated beverage model system at 4±1 °C, the presence of tannic acid (1:1, w/v) increased the half-life time by 187 h compared to the control samples.
Article
Determination of anthocyanins in fresh and concentrated juices can be a parameter for the assessment of authenticity and quality of blood orange juices. This work reports an HPLC/UV-Vis method developed for quantitative determination of anthocyanins in blood orange juices, by using a calibration curve obtained for standard cyanidin-3-glucoside. Samples analysed have been obtained from fruits of different trees (one for each of the varieties: ‘Moro’, ‘Tarocco’, ‘Sanguinello’ and ‘Sanguinello nocellare’) harvested about every 15 days during the 1998 productive season. Seasonal variation has been also evaluated. HPLC results were compared with spectrophotometric measurements, using a calibration curve obtained for cyanidin-3-glucoside solutions. The two methods showed good agreement, but the results obtained greately differed with the data reported in the literature.
Article
Aside from the nutritional relevance of some carotenoids owing to their vitamin A activity, these pigments are increasingly drawing the interest of researchers as they may be somehow implicated in the prevention and/or protection against major human diseases. Orange juice is an important source of carotenoids, which, along with its nutritional importance worldwide, have stimulated the development of diverse analytical methodologies for the analysis of these isoprenoid compounds. In this paper, we review different methods used to this end, so that not only researchers but also the industry can choose the most suitable for their purposes. In addition, discussion about particular difficulties of carotenoid analysis in orange juice and research needs are also included.
Article
Recent attention has been given to the influence of dietary factors on health and mental well-being. Oxidative stress is associated with many diseases including neurodegenerative disorders. Dietary flavonoids exert cardioprotective, chemopreventive, and neuroprotective effects. The biological activities of flavonoids have been attributed to their antioxidant, anti-inflammatory, and signaling properties. A clear understanding of the mechanisms of action, as either antioxidants or signaling molecules, is crucial for the application of flavonoids as interventions in neurodegeneration and as brain foods. Citrus flavonoids exert little adverse effect and have low or no cytotoxicity to healthy, normal cells. The main citrus flavonoids can also traverse the blood-brain barrier; hence, they are promising candidates for intervention in neurodegeneration and as constituents in brain foods. In this review, we discuss the bioactivity, multiple neuroprotection mechanisms, and antioxidant and signaling properties of citrus flavonoids. Receptor-mediated neuroprotective actions and parallel signaling pathways are also explored. Finally, the induction of cellular defense proteins against oxidative stress and neurotoxicity by hesperetin, a main and widespread citrus flavonoid, are also discussed. It is suggested that citrus fruits, which are rich in abundant sources of hesperetin and other flavonoids, are promising for the development of general food-based neuroprotection and brain foods.
Article
The health benefits associated with the consumption of anthocyanin-containing foods are extensively documented. Mature fruits of blood oranges and their hybrids are characterized by the presence of these bioactive pigments, the abundance of which can be enhanced by storing fruit at cooling nonfreezing temperature. In this work the effects of short low-temperature exposure (4 °C × 15 days) upon orange anthocyanin content and the expression of structural genes belonging to the pigment biosynthesis pathway were investigated. The results highlight that anthocyanin levels of fruit exposed to cold sharply increase, reaching, after 6 days of storage, a value 8 times higher than that observed in the time zero samples, thus suggesting that fruit with enhanced health-related attributes might be obtained at this storage stage. The analysis of gene expression shows that the amount of transcripts of all considered genes (CM1, PAL, CHS, DFR, ANS, UFGT, and GST) sharply increased after 3-6 days of cold storage, confirming previous data showing that the biosynthesis of anthocyanins is a cold-regulated pathway. By comparing the expression of selected genes (PAL, DFR, and UFGT) between blood and common oranges, it turns out that those genes strictly involved in anthocyanin biosynthesis are not cold responsive in common oranges. Moreover, the data highlight that the EST encoding the transcription factor NAC domain protein is selectively induced by cold in blood oranges but not in common oranges, thus proposing it as a candidate gene specifically involved in blood orange response to cold exposure.
Article
The basis for the vivid color of carotenoids and their antioxidant activity is the multiple conjugated double bonds, which are characteristic for these phytonutrients. Moreover, the cleavage of these oxidation-prone double bonds leads to the formation of apocarotenoids. A large number of carbonyl-containing oxidation products are expected to be produced as a result of carotenoid oxidation and these can be further metabolized into the corresponding acids and alcohols. As discussed in this review, many, but not all, of these potential products have been detected and identified in plants as well as in human and animal plasma and tissues. Some of these compounds were found to be biologically active as anticancer agents. In addition to the inhibition of cancer cell proliferation, several carotenoid metabolites were shown to modulate the activity of various transcription systems. These include ligand-activated nuclear receptors, such as the retinoic acid receptor, retinoid X receptor, peroxisome proliferator-activated receptor and estrogen receptor, as well as other transcription systems that have an important role in cancer, such as the electrophile/antioxidant response element pathway and nuclear factor-κB. Therefore, apocarotenoids can be considered as natural compounds with multifunctional, rather than monofunctional, activity and, thus, can be useful in the prevention of cancer and other degenerative diseases.