Zeaxanthin Content Research Articles

The Na+ /Ca2+ antiporter slr0681 affects carotenoid production in Synechocystis sp. PCC 6803 under high-light stress.

Carotenoids play key roles in photosynthesis and are widely used in foods as natural pigments, antioxidants, and health-promoting compounds. Enhancing carotenoid production in microalgae via biotechnology has become an important area of research. We knocked out the Na+ /Ca2+ antiporter gene slr0681 in Synechocystis sp. PCC 6803 via homologous recombination and evaluated the effects on carotenoid production under normal (NL) and high-light (HL) conditions. On day 7 of NL treatment in calcium ion (Ca2+ )-free medium, the cell density of Δslr0681 decreased by 29% compared to the wild type (WT). After 8 days of HL treatment, the total carotenoid contents decreased by 35% in Δslr0681, and the contents of individual carotenoids were altered: myxoxanthophyll, echinenone, and β-carotene contents increased by 10%, 50%, and 40%, respectively, while zeaxanthin contents decreased by ~40% in Δslr0681 versus the WT. The expression patterns of carotenoid metabolic pathway genes also differed: ipi expression increased by 1.2- to 8.5-fold, whereas crtO and crtR expression decreased by ~90% and 60%, respectively, in ∆slr0681 versus the WT. In addition, in ∆slr0681, the expression level of psaB (encoding a photosystem I structural protein) doubled, whereas the expression levels of the photosystem II genes psbA2 and psbD decreased by ~53% and 84%, respectively, compared to the WT. These findings suggest that slr0681 plays important roles in regulating carotenoid biosynthesis and structuring of the photosystems in Synechocystis sp. This study provides a theoretical basis for the genetic engineering of microalgae photosystems to increase their economic benefits and lays the foundation for developing microalgae germplasm resources with high carotenoid contents. © 2023 Society of Chemical Industry.

Changes in the Content of Carotenoids in Moss Shoots Hylocomium splendens Hedw. under Conditions of Temperature Stress

The ability of plants to adapt to unfavorable living conditions is a necessary condition for the survival of plants, the preservation of the genotype, and the maintenance of flora diversity. A promising approach to solving the problem of increasing plant resistance is to study the mechanisms of stress resistance of “extremophiles”, including mosses, higher nonvascular plants. The relative simplicity of their anatomical structure and ability to survive in unfavorable environmental conditions make these evolutionarily ancient plants ideal models for studying adaptation mechanisms. It is known that the functional activity of the photosynthetic apparatus can change dynamically under the influence of stress factors. In this work, we conducted a study of stress-induced changes in the content of carotenoids in the forest moss Hylocomium splendens Hedw. under temperature stress conditions. We have identified the main carotenoids of H. splendens moss. It has been established that the relative content of lutein, β-carotene, and zeaxanthin increased under the influence of negative and elevated temperatures, while the total content of carotenoids decreased under temperature stress. It was shown that 1 h of exposure to unfavorable temperatures led to a significant decrease in nonphotochemical quenching of chlorophyll fluorescence a, with stronger changes observed when exposed to negative temperatures. Transcript level analysis of HsLUT1, one of the key genes for lutein biosynthesis, showed a significant increase of four to five times under temperature stress. Thus, our data revealed that changes in the expression of the carotenoid biosynthesis gene are accompanied by changes in their content under temperature stress. The data obtained expand our knowledge of resistance mechanisms in bryophytes and will contribute to the understanding of evolutionary changes in stress resistance in higher plants.

Overproduction of Xanthophyll Pigment in Flavobacterium sp. JSWR-1 under Optimized Culture Conditions.

Flavobacterium can synthesize xanthophyll, particularly the pigment zeaxanthin, which has significant economic value in nutrition and pharmaceuticals. Recently, the use of carotenoid biosynthesis by bacteria and yeast fermentation technology has shown to be very efficient and offers significant advantages in large-scale production, cost-effectiveness, and safety. In the present study, JSWR-1 strain capable of producing xanthophyll pigment was isolated from a freshwater reservoir in Wanju-gun, Republic of Korea. Based on the morphological, physiological, and molecular characteristics, JSWR-1 classified as belonging to the Flavobacterium species. The bacterium is strictly aerobic, Gram-negative, rod-shaped, and psychrophilic. The completed genome sequence of the strain Flavobacterium sp. JSWR-1 is predicted to be a single circular 3,425,829-bp chromosome with a G+C content of 35.2% and 2,941 protein-coding genes. The optimization of carotenoid production was achieved by small-scale cultivation, resulting in zeaxanthin being identified as the predominant carotenoid pigment. The enhancement of zeaxanthin biosynthesis by applying different light-irradiation, variations in pH and temperature, and adding carbon and nitrogen supplies to the growth medium. A significant increase in intracellular zeaxanthin concentrations was also recorded during fed-batch fermentation achieving a maximum of 16.69 ± 0.71 mg/l, corresponding to a product yield of 4.05 ± 0.15 mg zeaxanthin per gram cell dry weight. Batch and fed-batch culture extracts exhibit significant antioxidant activity. The results demonstrated that the JSWR-1 strain can potentially serve as a source for zeaxanthin biosynthesis.

Enrichment efficiency of lutein in eggs and its function in improving fatty liver hemorrhagic syndrome in aged laying hens

In this study, we evaluated the enrichment efficiency of lutein in eggs and its function in preventing fatty liver hemorrhagic syndrome (FLHS) in aged laying hens. Five groups of laying hens (65 wk old) were fed basal diets supplemented with 0, 30, 60, 90, or 120 mg/kg of lutein. The supplementation period lasted 12 wk followed by 2 wk of lutein depletion in feed. The results revealed that lutein efficiently enriched the egg yolks and improved their color with a significant increase in relative redness (P < 0.001). Lutein accumulation increased in the egg yolk until day 10, then depletion reached a minimum level after 14 d. Overall, zeaxanthin content in all the groups was similar throughout the experimental period. However, triglycerides and total cholesterol were significantly decreased in the liver (P < 0.05) but not significantly different in the serum (P > 0.05). In the serum, the lipid metabolism enzyme acetyl-CoA synthetase was significantly reduced (P < 0.05), whereas dipeptidyl-peptidase 4 was not significantly different (P > 0.05), and there was no statistical difference of either enzyme in the liver (P > 0.05). Regarding oxidation and inflammation-related indexes, malondialdehyde, tumor necrosis factors alpha, interleukin-6, and interleukin-1 beta were decreased, whereas superoxide dismutase and total antioxidant capacity increased in the liver (P < 0.001). The function of lutein for the same indexes in serum was limited. It was concluded that lutein efficiently enriched the egg yolk of old laying hens to improve their color and reached the highest level on day 10 without being subject to a significant conversion into zeaxanthin. At the same time, lutein prevented liver steatosis in aged laying hens by exerting strong antioxidant and anti-inflammatory functions, but also through the modulation of lipid metabolism, which may contribute to reducing the incidence of FLHS in poultry.

Inter-Organellar Effects ofDefective ER-Localized Linolenic Acid Formation onThylakoid Lipid Composition, Non-Photochemical Quenching ofChlorophyll Fluorescence andXanthophyll Cycle Activity inthe Arabidopsis fad3 Mutant.

Monogalactosyldiacylglycerol (MGDG) is the main lipid constituent of thylakoids and a structural component of photosystems and photosynthesis-related proteo-lipid complexes in green tissues. Previously reported changes in MGDG abundance upon stress treatments are hypothesized to reflect mobilization of MGDG-based polyunsaturated lipid intermediates to maintain extraplastidial membrane integrity. While exchange of lipid intermediates between compartmental membranes is well documented, physiological consequences of mobilizing an essential thylakoid lipid, such as MGDG, for an alternative purpose are not well understood. Arabidopsis seedlings exposed to mild (50 mM) salt treatment displayed significantly increased abundance of both MGDG and the extraplastidial lipid, phosphatidylcholine (PC). Interestingly, similar increases in MGDG and PC were observed in Arabidopsis fad3 mutant seedlings defective in endoplasmic reticulum (ER)-localized linolenic acid formation, in which compensatory plastid-to-ER-directed mobilization of linolenic acid-containing intermediates takes place. The postulated (salt) or evident (fad3) plastid-ER exchange of intermediates concurred with altered thylakoid function according to parameters of photosynthetic performance. While salt treatment of wild-type seedlings inhibited photosynthetic parameters in a dose-dependent manner, interestingly, untreated fad3 mutants did not show overall reduced photosynthetic quantum yield. By contrast, we observed a reduction specifically of non-photochemical quenching (NPQ) under high light, representing only part of observed salt effects. The decreased NPQ in the fad3 mutant was accompanied by reduced activity of the xanthophyll cycle, leading to a reduced concentration of the NPQ-effective pigment zeaxanthin. The findings suggest that altered ER-located fatty acid unsaturation and ensuing inter-organellar compensation impacts on the function of specific thylakoid enzymes, rather than globally affecting thylakoid function.

Cultivation manipulating zeaxanthin-carotenoid production in Arthrospira (Spirulina) platensis under light and temperature stress

Arthrospira (Spirulina) platensis is highly nutritious and most promising cyanobacterium for healthy compounds. In this study, the effect of light and temperature stress on zeaxanthin production in A. platensis C1 (PCC9438) were investigated. Under an optimal condition (35 °C, PPFD of 100 μmol photons m−2 s−1), the algal growth revealed a specific growth rate (μ) of 0.024 h−1, with the carotenoid yield and content of 3.64 mg L−1 and 4.66 mg g−1, respectively, when cells were grown for 96 h. Whereas that of the isothermally grown under sub-optimal temperatures (16 °C, 20 °C, 37 °C, 39 °C and 43 °C), the growth rates and carotenoid yields were very low, ranging from 0.001 to 0.021 h−1 of the specific growth rate, and varied from 0.17 to 3.05 mg L−1 and 0.64 to 4.51 mg g−1 of carotenoid yield and content, respectively. Nevertheless, employing a temperature shift strategy by transferring the algal culture to high temperature (42 °C) led to the increment of total carotenoids by about 12 % and zeaxanthin content and yield by 35.6 % and 22.1 %, respectively, compared to the control, which had a yield and content of 0.68 mg L−1 and 0.87 mg g−1, respectively, within 48 h. Furthermore, altering light intensities during the cultivation period, algal biomass significantly increased by 59 % under high light stress (1000 μmol photons m−2 s−1) compared to the control (0.78 g L−1). Additionally, zeaxanthin yield and content increased by 104.4 % and 28.7 %, respectively, under 1000 μmol photons m−2 s−1. We therefore proposed that light/temperature stress shifting strategy for the cultivation of A. platensis C1 could be used to enhance its nutraceutical value.

Distinct Impacts of UV-A Light Wavelengths on Nutraceutical and Mineral Contents in Green and Purple Basil Cultivated in a Controlled Environment

Controlled environment agricultural (CEA) systems create technological opportunities for the higher nutritional value of vegetables and herbs. It was hypothesized that UV-A light, supplementing basal light emitting diode (LED) illumination in CEA, would enhance growth and nutritional value (nutraceutical compounds and mineral element contents) in purple and green basil in a UV-A wavelength-specific manner. Therefore, blue (452 nm) and red (662 nm) 1:10 basal LED lighting (250 μmol m−2 s−1, 16 h) was supplemented with 1 mW cm−2 of 343, 366, 386, or 402 nm UV-A LED light for green ‘Italiano classico’ and purple ‘Red rubin’ basil cultivation. Different wavelengths have specific impacts for two basil genotypes, and certain light wavelengths should be selected to boost growth or to alter the contents of specific nutraceutical compounds. UV-A/violet 402 nm light enhanced growth, chicoric acid, β carotene, lutein, and zeaxanthin contents in green basil, while 343 nm UV-A light increased fresh weight, ascorbic acid, and carotenoid content in purple basil. UV-A light of 386 nm has the most negligible impact on reducing mineral element (P, Ca, Fe, K, Mg, Mn, and Zn) contents in basil. Understanding the wavelength dependence of plant responses to UV-A is essential for optimizing quality preservation and improving basil cultivation in controlled environment systems.

Lutein and Zeaxanthin Content in 21 Plant Species from a Very Humid Premontane Forest in Colombia Palatable for Free-Range Laying Hens.

Xanthophylls, such as lutein and zeaxanthin, have several functions in both plants and humans, including detoxification of oxidants (reactive oxygen species (ROS) and other radicals), maintenance of the structural and functional integrity of biological membranes, and photoprotection from intense light damage. The objective of the present study was to investigate the lutein and zeaxanthin content of 21 species of plants from a very humid premontane forest in Colombia during both dry and rainy seasons. The plants were selected based on being voluntarily eaten by laying hens under free-range conditions. Lutein and zeaxanthin were identified and quantified by high-performance liquid chromatography (HPLC). The results showed that all plants tested contained lutein, at levels ranging from 65.7 to 350 µg/g. Zeaxanthin levels were much lower (2.2 to 26.2 µg/lg) and were detected in only 5 of the 21 plants analyzed. Given that the lutein content of the plants tested in the present study was found to be comparable to that reported in marigold flowers (4-800 µg/g), it is possible that these plants can be used as a source of lutein in free-range laying hen production systems.

Preterm Pigs Fed Donor Human Milk Have Greater Liver β-Carotene Concentrations than Pigs Fed Infant Formula

BackgroundMilk carotenoids may support preterm infant health and neurodevelopment. Infants fed human milk often have higher blood and tissue carotenoid concentrations than infants fed carotenoid-containing infant formula (IF). Donor human milk (DHM) is a supplement to mother’s own milk, used to support preterm infant nutrition. ObjectivesWe tested whether tissue and plasma β-carotene concentrations would be higher in preterm pigs fed pasteurized DHM versus premature IF. MethodsThis is a secondary analysis of samples collected from a study of the effects of enteral diet composition on necrotizing enterocolitis incidence. Preterm pigs received partial enteral feeding of either DHM (n = 7) or premature IF (n = 7) from 2 to 7 d of age. The diets provided similar β-carotene (32 nM), but DHM had higher lutein, zeaxanthin, and lycopene, whereas IF had higher total vitamin A. Plasma, liver, and jejunum carotenoid and vitamin A concentrations were measured by HPLC-PDA. Jejunal expression of 12 genes associated with carotenoid and lipid metabolism were measured. ResultsLiver β-carotene concentrations were higher in DHM- than IF-fed piglets (23 ± 4 compared with 16 ± 2 μg/g, respectively, P = 0.0024), whereas plasma and jejunal β-carotene concentrations were similar between diets. Liver vitamin A stores were higher in piglets fed IF than DHM (50.6 ± 10.1 compared with 30.9 ± 7.2 μg/g, respectively, P=0.0013); however, plasma vitamin A was similar between groups. Plasma, liver, and jejunum concentrations of lutein, zeaxanthin, and lycopene were higher with DHM than IF feeding. Relative to piglets fed DHM, jejunal low density lipoprotein receptor (Ldlr) expression was higher (61%, P = 0.018) and cluster determinant 36 (Cd36) expression (−27%, P = 0.034) was lower in IF-fed piglets. ConclusionsPreterm pigs fed DHM accumulate more liver β-carotene than IF-fed pigs. Future studies should further investigate infant carotenoid bioactivity and bioavailability.

Characterization of an efficient CRISPR-iCas9 system in Yarrowia lipolytica for the biosynthesis of carotenoids.

The application of clustered regularly interspaced short palindromic repeats-Cas (CRISPR-Cas9) technology in the genetic modification of Yarrowia lipolytica is challenged by low efficiency and low throughput. Here, a highly efficient CRISPR-iCas9 (with D147Y and P411T mutants) genetic manipulation tool was established for Y. lipolytica, which was further utilized to integrate carotene synthetic key genes and significantly improve the target product yield. First, CRISPR-iCas9 could shorten the time of genetic modification and enable the rapid knockout of nonsense suppressors. iCas9 can lead to more than 98% knockout efficiency for NHEJ-mediated repair after optimal target disruption of a single gene, 100% knockout efficiency for a single gene-guided version, and more than 80% knockout efficiency for multiple genes simultaneously in Y. lipolytica. Subsequently, this technology allowed for rapid one-step integration of large fragments (up to 9902-bp) of genes into chromosomes. Finally, YL-ABTG and YL-ABTG2Z were further constructed through CRISPR-iCas9 integration of key genes in a one-step process, resulting in a maximum β-carotene and zeaxanthin content of 3.12 mg/g and 2.33 mg/g dry cell weight, respectively. Therefore, CRISPR-iCas9 technology provides a feasible approach to genetic modification for efficient biosynthesis of biological compounds in Y. lipolytica. KEY POINTS: • iCas9 with D147Y and P411T mutants improved the CRISPR efficiency in Y. lipolytica. • CRISPR-iCas9 achieved efficient gene knockout and integration in Y. lipolytica. • CRISPR-iCas9 rapidly modified Y. lipolytica for carotenoid bioproduction.

How do barley plants with impaired photosynthetic light acclimation survive under high-light stress?

Main ConclusionWHIRLY1 deficient barley plants surviving growth at high irradiance displayed increased non-radiative energy dissipation, enhanced contents of zeaxanthin and the flavonoid lutonarin, but no changes in α-tocopherol nor glutathione.Plants are able to acclimate to environmental conditions to optimize their functions. With the exception of obligate shade plants, they can adjust their photosynthetic apparatus and the morphology and anatomy of their leaves to irradiance. Barley (Hordeum vulgare L., cv. Golden Promise) plants with reduced abundance of the protein WHIRLY1 were recently shown to be unable to acclimatise important components of the photosynthetic apparatus to high light. Nevertheless, these plants did not show symptoms of photoinhibition. High-light (HL) grown WHIRLY1 knockdown plants showed clear signs of exposure to excessive irradiance such as a low epoxidation state of the violaxanthin cycle pigments and an early light saturation of electron transport. These responses were underlined by a very large xanthophyll cycle pool size and by an increased number of plastoglobules. Whereas zeaxanthin increased with HL stress, α-tocopherol, which is another lipophilic antioxidant, showed no response to excessive light. Also the content of the hydrophilic antioxidant glutathione showed no increase in W1 plants as compared to the wild type, whereas the flavone lutonarin was induced in W1 plants. HPLC analysis of removed epidermal tissue indicated that the largest part of lutonarin was presumably located in the mesophyll. Since lutonarin is a better antioxidant than saponarin, the major flavone present in barley leaves, it is concluded that lutonarin accumulated as a response to oxidative stress. It is also concluded that zeaxanthin and lutonarin may have served as antioxidants in the WHIRLY1 knockdown plants, contributing to their survival in HL despite their restricted HL acclimation.

Deposition and bioconversion law of β-carotene in laying hens after long-term supplementation under adequate vitamin A status in the diet

β-Carotene, because it is the precursor of vitamin A and has versatile biological roles, has been applied as a feed additive in the poultry industry for a long time. In this study, we investigated the deposition and bioconversion of β-carotene in laying hens. A total of 600 Hy-line brown laying hens at 40 wk of age were randomly divided into 5 dietary treatments, each group's dietary supplemental levels of β-carotene were 0, 15, 30, 60, 120 mg/kg feed, and the vitamin A levels were all 8,000 IU/kg. After 14-wk trial, samples were collected, then carotenoids and different forms of vitamin A were detected using the novel method developed by our laboratory. We found that dietary β-carotene treatment had no significant effects on laying hens' production performance and egg quality (P > 0.05), except the yolk color. The deposition of β-carotene in the body gradually increased (P < 0.01) with the supplemental dose, whereas the contents of lutein and zeaxanthin decreased (P < 0.05). When the β-carotene supplemental level was above 30 mg/kg in the diet, the different forms of vitamin A in in serum, liver, ovary, and yolks were increased compared to the control group (P < 0.05). However, these indicators decreased when the additional dose was 120 mg/kg. Moreover, the mRNA levels of the genes involved in β-carotene absorption, bioconversion, and negative feedback regulation in duodenal mucosa and liver were upregulated after long-term feeding (P < 0.05). Histological staining of the ovaries indicated that the deposition of β-carotene led to a lower rate of follicle atresia (P < 0.05), and this positive effects may be related to the antioxidant function of β-carotene, which caused a reduction of oxidation products in the ovary (P < 0.05). Altogether, β-carotene could accumulate in laying hens intactly and exert its biological functions in tissue. Meanwhile, a part of β-carotene could also be converted into vitamin A but this bioconversion has an upper limit and negative feedback regulation.

Physiological Significance of the Heterogeneous Distribution of Zeaxanthin and Lutein in the Retina of the Human Eye

Zeaxanthin and lutein are xanthophyll pigments present in the human retina and particularly concentrated in its center referred to as the yellow spot (macula lutea). The fact that zeaxanthin, including its isomer meso-zeaxanthin, is concentrated in the central part of the retina, in contrast to lutein also present in the peripheral regions, raises questions about the possible physiological significance of such a heterogeneous distribution of macular xanthophylls. Here, we attempt to address this problem using resonance Raman spectroscopy and confocal imaging, with different laser lines selected to effectively distinguish the spectral contribution of lutein and zeaxanthin. Additionally, fluorescence lifetime imaging microscopy (FLIM) is used to solve the problem of xanthophyll localization in the axon membranes. The obtained results allow us to conclude that one of the key advantages of a particularly high concentration of zeaxanthin in the central part of the retina is the high efficiency of this pigment in the dynamic filtration of light with excessive intensity, potentially harmful for the photoreceptors.

Plasma Carotenoids and Polyphenols and Their Association with MetS: The Need for Nutritional Interventions.

Metabolic syndrome (MetS) is characterized by increased pro-oxidative stress and a chronic inflammation state and their consequent alterations. Several studies have highlighted the protective effect of carotenoids and polyphenols in MetS patients. This study aimed to evaluate the plasma level of selected carotenoids and polyphenols and to determine their relationship with MetS severity, MetS components, and inflammatory markers in Polish adults with metabolic disorders. It was designed as a cross-sectional study. The final study group comprised 275 adults, including 158 women and 117 men. Data were collected on the frequency of consumption of selected food groups. Anthropometric measurements and blood samples were taken to determine the concentration of carotenoids, polyphenols, and indicators (parameters) of metabolic disorders. Plasma concentrations of selected carotenoids and polyphenols were low in adults with MetS. The highest concentrations of carotenoids and polyphenols in the blood were observed for lutein and phenolic acids (including gallic and p-coumaric acids). Nevertheless, a correlation was found between the individual bioactive compounds and MetS components. In terms of the lipid profile, our study showed that the plasma of the selected carotenoids and polyphenols positively correlated with HDL cholesterol (zeaxanthin; total carotenoids), LDL cholesterol (chlorogenic acid), triglycerides (lycopene), and the total cholesterol (kaempferol). We found that the level of CRP as a marker of inflammation negatively correlated with the concentration of zeaxanthin. In our study group, no relationship was found between the dietary antioxidant intensity and the variables studied, which may be attributed to the low frequency of consumption of the sources of bioactive compounds, such as carotenoids and polyphenols, but also to the metabolic disorders. Further research is needed to determine whether these associations are causally related to the metabolic syndrome or are a result of the pathologies of the syndrome or improper diet with a low intake of vegetables and fruit.

Photosynthetic efficiency and transcriptome analysis of Dunaliella salina under hypersaline: a retrograde signaling mechanism in the chloroplast.

Understanding the molecular mechanisms of environmental salinity stress tolerance and acclimation strategies by photosynthetic organisms facilitates accelerating the genetic improvement of tolerant economically important crops. In this study, we have chosen the marine algae Dunaliella (D.) salina, a high-potential and unique organism that shows superior tolerance against abiotic stresses, especially hypersaline conditions. We have grown the cells in three different salt concentrations 1.5M NaCl (control), 2M NaCl, and 3M NaCl (hypersaline). Fast chlorophyll fluorescence analysis showed increased initial fluorescence (Fo) and decreased photosynthetic efficiency, indicating hampered photosystem II utilization capacity under hypersaline conditions. Also, the reactive oxygen species (ROS) localization studies and quantification revealed elevated accumulation of ROS was observed in the chloroplast in the 3M condition. Pigment analysis shows a deficit in chlorophyll content and increased carotenoid accumulation, especially lutein and zeaxanthin content. This study majorly explored the chloroplast transcripts of the D. salina cell as it is the major environmental sensor. Even though most of the photosystem transcripts showed moderate upregulation in hypersaline conditions in the transcriptome study, the western blot analysis showed degradation of the core as well as antenna proteins of both the photosystems. Among the upregulated chloroplast transcripts, chloroplast Tidi, flavodoxin IsiB, and carotenoid biosynthesis-related protein transcripts strongly proposed photosynthetic apparatus remodeling. Also, the transcriptomic study revealed the upregulation of the tetrapyrrole biosynthesis pathway (TPB) and identified the presence of a negative regulator of this pathway, called the s-FLP splicing variant. These observations point towards the accumulation of TPB pathway intermediates PROTO-IX, Mg-PROTO-IX, and P-Chlide, those earlier reported as retrograde signaling molecules. Our comparative transcriptomic approach along with biophysical and biochemical studies in D. salina grown under control (1.5 M NaCl) and hypersaline (3M NaCl) conditions, unveil an efficient retrograde signaling mechanism mediated remodeling of photosynthetic apparatus.

Carotenoid and transcriptome profiles of a novel citrus cultivar ‘Jinlegan’ reveal mechanisms of yellowish fruit formation

Citrus fruit coloration is one of the vital quality traits that is determined primarily by the composition and content of carotenoids. Natural citrus fruit pigment mutants are available to study diverse and complex carotenoid metabolism. Here, ‘Jinlegan’ (MT) tangor is a spontaneous bud mutant derived from ‘Shiranuhi’ (WT) with distinctive bright yellow fruit. High performance liquid chromatography (HPLC) analysis revealed that the yellowish MT flavedo and pulp were primarily caused by the decrease in total carotenoid content. The total carotenoid content in MT flavedo was reduced by 75% (79.98 μg/g DW) compared with that in WT (318.40 μg/g DW), including approximately 84%, 80%, and 60% reductions in the contents of β-cryptoxanthin, violaxanthin and zeaxanthin, respectively. The total carotenoid content in MT pulp was 60% lower (10.09 μg/g DW) than that in WT pulp (26.61 μg/g DW), which was mainly due to a 70% and 30% decrease in the contents of β-cryptoxanthin and zeaxanthin, respectively. To explore the molecular mechanism underlying carotenoid variation in MT, RNA-seq analyses were performed on the flavedo and pulp of WT and MT at five developmental stages. The reduced expression of phytoene synthase (CrPSY) and β-carotenehydroxylase 1 (CrBCH1) in the flavedo and pulp of MT at the breaker stage might be the major cause of the reduction in carotenoids. Weighted gene co-expression network analysis (WGCNA) further identified 23 key transcription factors that are closely associated with carotenoid accumulation. This study demonstrated a comprehensive picture of the metabolic and transcriptional alterations of a unique yellowish citrus fruit mutant, which provides new insights into the molecular regulation of carotenoid accumulation in citrus fruit.

Conteúdo de luteína e zeaxantina em milho importado de três países do continente americano e em milho cultivado em território colombiano

ABSTRACT Lutein and zeaxanthin are the major xanthophyll pigments found in corn kernels. These pigments provide the orange-red color of the broiler chicken skin and of the egg yolk. Therefore, knowing the corn xanthophyll content is important for the poultry feed producer. The objective of this study was to determine the lutein and the zeaxanthin content in corn cultivated in Colombia and in corn imported to Colombia from the United States, Argentina, and Brazil. Large differences in total lutein plus zeaxanthin content were found among the corn samples analyzed, with the highest mean level found in Colombian corn (2,758µg/100g), followed by Argentina (1,861µg/100g), United States (1,041µg/100g) and Brazil (947µg/100g). Large differences in lutein plus zeaxanthin content were also found among different corn hybrids cultivated in Colombia. Differences among geographical regions might be due to differences in UV-B radiation or in the light hours received by the crop during its growth. The differences among different corn hybrids might probably be due to genetic differences. Corn growers might be interested in cultivating hybrids higher in lutein and zeaxanthin as these pigments are very important in poultry production and human eye health.

AcMADS32 positively regulates carotenoid biosynthesis in kiwifruit by activating AcBCH1/2 expression

Fruits provide abundant carotenoid nutrients for humans, whereas the understanding of the transcriptional regulatory mechanisms of carotenoids in fruits is still limited. Here, we identified a transcription factor AcMADS32 in kiwifruit, which was highly expressed in the fruit, correlated with carotenoid content and localized in the nucleus. The silencing expression of AcMADS32 significantly reduced the content of β-carotene and zeaxanthin and expression of β-carotene hydroxylase gene AcBCH1/2 in kiwifruit, while transient overexpression increased the accumulation of zeaxanthin, suggesting that AcMADS32 was an activator involved in the transcriptional regulation of carotenoid in fruit. When AcMADS32 was further stably transformed into kiwifruit, the content of total carotenoid and components in the leaves of transgenic lines significantly increased, and the expression level of carotenogenic genes was up-regulated. Moreover, Y1H and dual luciferase reporter experiments confirmed that AcMADS32 directly bound the AcBCH1/2 promoter and activated its expression. Through Y2H assays, AcMADS32 can interact with other MADS transcription factor AcMADS30, AcMADS64 and AcMADS70. These findings will contribute to our understanding of the transcriptional regulation mechanisms underlying carotenoid biosynthesis in plants.

Formation, Structural Characterization, and Functional Properties of Corn Starch/Zeaxanthin Composites.

Zeaxanthin is a natural xanthophyll carotenoid and the main macular pigment that protects the macula from light-initiated oxidative damage, but it has poor stability and low bioavailability. Absorption of this active ingredient into starch granules as a carrier can be used to improve both zeaxanthin stability and controlled release. Optimization using three variables judged important for optimizing the system (reaction temperature of 65 °C, starch concentration of 6%, and reaction time of 2 h) was conducted for incorporation of zeaxanthin into corn starch granules, aiming for high zeaxanthin content (2.47 mg/g) and high encapsulation efficiency (74%). Polarized-light microscopy, X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy showed that the process partially gelatinized corn starch; additionally, it showed the presence of corn starch/zeaxanthin composites, with the zeaxanthin successfully trapped in corn starch granules. The half-life time of zeaxanthin in corn starch/zeaxanthin composites increased to 43 days as compared with that of zeaxanthin alone (13 days). The composites show a rapid increase in zeaxanthin release with in vitro intestinal digestion, which is favorable for possible use in living systems. These findings could have application in designing effective starch-based carriers of this bioactive ingredient with enhanced storage stability and improved intestines-targeted controlled-release delivery.

Antioxidant Properties of Cranberry Leaves and Walnut Meal and Their Effect on Nutritional Quality and Oxidative Stability of Broiler Breast Meat.

Dietary sources of bioactive compounds in animal diets, are the natural way to produce animal food products with improved nutritional quality. The present study aimed to test the hypothesis of a synergistic effect of bioactive compounds of cranberry leaf powder and walnut meal on the nutritional quality and antioxidant compounds of broiler meat. An experiment was conducted on 160 COBB 500 broiler chickens, housed in an experimental hall with permanent wood shave litter in boxes of 3 m2. The six dietary treatments were based on corn and soybean meal; three experimental groups were fed diets supplemented with cranberry leaves (CLs) with three inclusion rates (0% in the control group and CL 1% and CL 2%); two experimental groups were fed diets supplemented with walnut meal (WM) with two inclusion rates (0% and WM 6%); and two groups were fed diets with a combination of the selected supplements (CL 1% WM 6% and CL 2% WM 6%). The results show that the experimental groups registered higher concentrations of copper and iron compared with the control group. An antagonist effect was noticed on lipophilic compounds, and the lutein and zeaxanthin concentrations presented a dose-dependent increasing effect under CL influence, while vitamin E concentrations decreased in the same manner. The dietary WM positively influenced vitamin E deposits on breast tissue. The dietary supplements did not produce any effect on the primary oxidation products, but the secondary products were influenced, and the maximum effect on the TBARS values were recorded for the dietary combination of CL 1% and WM 6%.