Β-carotene Accumulation Research Articles

Meeting the Vitamin A Requirement: The Efficacy and Importance ofβ-Carotene in Animal Species

Vitamin A is essential for life in all vertebrate animals. Vitamin A requirement can be met from dietary preformed vitamin A or provitamin A carotenoids, the most important of which is β-carotene. The metabolism of β-carotene, including its intestinal absorption, accumulation in tissues, and conversion to vitamin A, varies widely across animal species and determines the role that β-carotene plays in meeting vitamin A requirement. This review begins with a brief discussion of vitamin A, with an emphasis on species differences in metabolism. A more detailed discussion of β-carotene follows, with a focus on factors impacting bioavailability and its conversion to vitamin A. Finally, the literature on how animals utilize β-carotene is reviewed individually for several species and classes of animals. We conclude that β-carotene conversion to vitamin A is variable and dependent on a number of factors, which are important to consider in the formulation and assessment of diets. Omnivores and herbivores are more efficient at converting β-carotene to vitamin A than carnivores. Absorption and accumulation of β-carotene in tissues vary with species and are poorly understood. More comparative and mechanistic studies are required in this area to improve the understanding of β-carotene metabolism.

Metabolic Profiling of Dunaliella salina Shifting Cultivation Conditions to Nitrogen Deprivation

Dunaliella salina is a model chlorophyte microalga in studying carotenoid metabolism and osmoregulation. Nitrogen depletion plays an important role in inducing β-carotene accumulation of D. salina cells. However, the underlying mechanism is still unclear. In this study, the metabolic profiling of D. salina cells during the process of nitrogen deprivation was performed by gas chromatography-mass spectrometry. A total of 78 metabolites were identified and quantified, including 16 amino acids, 19 sugars, 13 organic acids, 11 alcohols, 11 fatty acids, 4 amines and 4 others. Nitrogen deprivation induced changes in saturation of fatty acids by increasing saturated fatty acids and decreasing polyunsaturated fatty acids in D. salina. The relative levels of metabolites such as sucrose, maltose and organic acids, which act as carbon skeleton, were increased, in contrast, glycerol, myo-inositol which are related to the osmoregulatory mechanism, kept constant under nitrogen deprivation condition. The levels of proline, glutamic acid and other metabolites, which were involved in protective function, were increased in nitrogen deprivation condition. The precursors of these metabolites are the intermediates of the Calvin cycle and the TCA cycle. The results of this research might be applicable to the interpretation of metabolic synthesis and fatty acid production during process of nitrogen deprivation and provide a new method for accumulating high amounts of carotenoids in D. salina.

A spontaneous bud mutant that causes lycopene and β-carotene accumulation in the juice sacs of the parental Guanxi pummelo fruits (Citrus grandis (L.) Osbeck)

Carotenoids are the second-most widespread pigments in nature and play crucial roles in plants, animals and humans. As one of the main fruit crops worldwide, citrus is an important source of carotenoids, and approximately 115 carotenoid compounds occur in citrus fruit. Recently, Red-fleshed pummelo, a spontaneous bud mutant of Guanxi pummelo that accumulate high-level carotenoids in edible portions, was discovered. The fruits, especially the juice sacs of Red-fleshed pummelo are light red in color, which is a feature of great interest to consumers and producers. In this study, the composition, content, characteristics of the lycopene β-cyclase (β-LCY) gene, and expression models of genes involved in the lycopene biosynthetic pathway of Red-fleshed and Guanxi pummelo fruit juice sacs were examined. Lycopene and β-carotene are the main pigments in Red-fleshed pummelo fruits, whereas the contents of these pigments are too low to be detected in Guanxi pummelo fruits. Four of the amino acids deduced from β-LCY cDNA were found to differ between Red-fleshed and Guanxi pummelo. Lycopene and β-carotene accumulation in Red-fleshed pummelo fruits were related to variation in the expression of genes related to the lycopene biosynthetic pathway, which mainly associated with the up-regulated expression of upstream genes and down-regulated expression of downstream genes in the lycopene biosynthesis pathway. This is a first reports of the biochemical and molecular investigation about Red-fleshed fruit mutant in pummelo.

A bulk segregant transcriptome analysis reveals metabolic and cellular processes associated with Orange allelic variation and fruit β-carotene accumulation in melon fruit.

BackgroundMelon fruit flesh color is primarily controlled by the “golden” single nucleotide polymorhism of the “Orange” gene, CmOr, which dominantly triggers the accumulation of the pro-vitamin A molecule, β-carotene, in the fruit mesocarp. The mechanism by which CmOr operates is not fully understood. To identify cellular and metabolic processes associated with CmOr allelic variation, we compared the transcriptome of bulks of developing fruit of homozygous orange and green fruited F3 families derived from a cross between orange and green fruited parental lines.ResultsPooling together F3 families that share same fruit flesh color and thus the same CmOr allelic variation, normalized traits unrelated to CmOr allelic variation. RNA sequencing analysis of these bulks enabled the identification of differentially expressed genes. These genes were clustered into functional groups. The relatively enriched functional groups were those involved in photosynthesis, RNA and protein regulation, and response to stress.ConclusionsThe differentially expressed genes and the enriched processes identified here by bulk segregant RNA sequencing analysis are likely part of the regulatory network of CmOr. Our study demonstrates the resolution power of bulk segregant RNA sequencing in identifying genes related to commercially important traits and provides a useful tool for better understanding the mode of action of CmOr gene in the mediation of carotenoid accumulation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0661-8) contains supplementary material, which is available to authorized users.

Metabolic Engineering of Wheat Provitamin A by Simultaneously Overexpressing CrtB and Silencing Carotenoid Hydroxylase (TaHYD).

Increasing the provitamin A content in staple crops via carotenoid metabolic engineering is one way to address vitamin A deficiency. In this work a combination of methods was applied to specifically increase β-carotene content in wheat by metabolic engineering. Endosperm-specific silencing of the carotenoid hydroxylase gene (TaHYD) increased β-carotene content 10.5-fold to 1.76 μg g(-1) in wheat endosperm. Overexpression of CrtB introduced an additional flux into wheat, accompanied by a β-carotene increase of 14.6-fold to 2.45 μg g(-1). When the "push strategy" (overexpressing CrtB) and "block strategy" (silencing TaHYD) were combined in wheat metabolic engineering, significant levels of β-carotene accumulation were obtained, corresponding to an increase of up to 31-fold to 5.06 μg g(-1). This is the first example of successful metabolic engineering to specifically improve β-carotene content in wheat endosperm through a combination of methods and demonstrates the potential of genetic engineering for specific nutritional enhancement of wheat.

High Preformed Vitamin A Intake during Pregnancy Prevents Embryonic Accumulation of Intact β-Carotene from the Maternal Circulation in Mice1–3

Background: The vitamin A precursor β-carotene (BC) promotes mammalian embryonic development by serving as a source of retinoids (vitamin A derivatives) to the developing tissues. In the Western world, increased consumption of dietary supplements, including vitamin A and BC, is common; however, the consequences of maternal high preformed vitamin A intake on embryonic uptake and metabolism of BC are poorly understood.Objective: This study investigated vitamin A and BC metabolism in developing mouse tissues after a single BC administration to pregnant wild-type (WT) mice fed purified diets with different vitamin A concentrations.Methods: WT dams fed a sufficient vitamin A (VA-S; 4.2 μg of retinol/g of diet), high vitamin A (VA-H; 33 μg of retinol/g of diet), or excess vitamin A (VA-E; 66 μg of retinol/g of diet) diet throughout gestation were intraperitoneally injected with BC or vehicle at 13.5 d postcoitum (dpc). At 14.5 dpc, retinoid and BC concentrations in maternal serum and liver, placenta, and embryo were quantified by HPLC; expressions of genes controlling retinoid and BC homeostasis were analyzed by quantitative polymerase chain reaction. Maternal lipoprotein BC concentrations were analyzed by density gradient ultracentrifugation followed by HPLC.Results: Intact BC was undetectable only in embryos from VA-E + BC dams. Relative to the VA-S + vehicle group, placentas from VA-S + BC dams showed 39% downregulation of LDL-receptor–related protein 1 (Lrp1 ); 35% downregulation of VLDL receptor (Vldlr); 56% reduced mRNA expression of β-carotene 15,15′-oxygenase (Bco1); and 80% upregulation of β-carotene 9′,10′-oxygenase (Bco2). Placental cytochrome P450, family 26, subfamily A, polypeptide 1 (Cyp26A1) was upregulated 2-fold in the VA-E group compared with the VA-S group, regardless of maternal treatment.Conclusions: In mice, transfer of intact BC to the embryo is attenuated by high tissue vitamin A concentrations. Maternal vitamin A intake and BC availability activate a placental transcriptional response to protect the embryo from retinoid and carotenoid excess.

A 'golden' SNP in CmOr governs the fruit flesh color of melon (Cucumis melo).

The flesh color of Cucumis melo (melon) is genetically determined, and can be white, light green or orange, with β-carotene being the predominant pigment. We associated carotenoid accumulation in melon fruit flesh with polymorphism within CmOr, a homolog of the cauliflower BoOr gene, and identified CmOr as the previously described gf locus in melon. CmOr was found to co-segregate with fruit flesh color, and presented two haplotypes (alleles) in a broad germplasm collection, one being associated with orange flesh and the second being associated with either white or green flesh. Allelic variation of CmOr does not affect its transcription or protein level. The variation also does not affect its plastid subcellular localization. Among the identified single nucleotide polymorphisms (SNPs) between CmOr alleles in orange versus green/white-flesh fruit, a single SNP causes a change of an evolutionarily highly conserved arginine to histidine in the CmOr protein. Functional analysis of CmOr haplotypes in an Arabidopsis callus system confirmed the ability of the CmOr orange haplotype to induce β-carotene accumulation. Site-directed mutagenesis of the CmOr green/white haplotype to change the CmOR arginine to histidine triggered β-carotene accumulation. The identification of the 'golden' SNP in CmOr, which is responsible for the non-orange and orange melon fruit phenotypes, provides new tools for studying the Or mechanism of action, and suggests genome editing of the Or gene for nutritional biofortification of crops.

Transcriptomic analysis of differentially expressed genes in an orange-pericarp mutant and wild type in pummelo (Citrus grandis).

BackgroundThe external colour of fruit is a crucial quality feature, and the external coloration of most citrus fruits is due to the accumulation of carotenoids. The molecular regulation of carotenoid biosynthesis and accumulation in pericarp is limited due to the lack of mutant. In this work, an orange-pericarp mutant (MT) which showed altered pigmentation in the pericarp was used to identify genes potentially related to the regulation of carotenoid accumulation in the pericarp.ResultsHigh Performance Liquid Chromatography (HPLC) analysis revealed that the pericarp from MT fruits had a 10.5-fold increase of β-carotene content over that of the Wild Type (WT). Quantitative real-time PCR (qRT-PCR) analysis showed that the expression of all downstream carotenogenic genes was lower in MT than in WT, suggesting that down-regulation is critical for the β-carotene increase in the MT pericarp. RNA-seq analysis of the transcriptome revealed extensive changes in the MT gene expression level, with 168 genes down-regulated and 135 genes up-regulated. Gene ontology (GO) and KEGG pathway analyses indicated seven reliable metabolic pathways are altered in the mutant, including carbon metabolism, starch and sucrose metabolism and biosynthesis of amino acids. The transcription factors and genes corresponding to effected metabolic pathways may involved in the carotenoid regulation was confirmed by the qRT-PCR analysis in the MT pericarp.ConclusionsThis study has provided a global picture of the gene expression changes in a novel mutant with distinct color in the fruit pericarp of pummelo. Interpretation of differentially expressed genes (DEGs) revealed new insight into the molecular regulation of β-carotene accumulation in the MT pericarp.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0435-3) contains supplementary material, which is available to authorized users.

Effect of saltiness on the growth and production of β-carotene in isolated Dunaliella sp. microalga from qom salt lake of Iran

The aim of this study was to achieve the highest β-carotene production by Dunaliella sp. isolates from under salinity stress factor. In this study, water samples from hyper-saline Qom Salt Lake were cultured in modified Johnson media and were treated at different salinities (1, 2 and 3 M of NaCl). In order to determine the optimal salinity required for the highest β-carotene accumulation, cell count of Dunaliella sp. isolates; total carotenoids and concentration of the β-carotene were determined by direct microscopic counting and spectrophotometry. In the samples with different salinities, the cell count and the β-carotene content of Dunaliella sp. ranged between 0.46 and 2.12×106 cell.ml-1 and 0.16 to 9.88 pg.cell-1, respectively. At the end of the experiments, the maximum cell content mean and the highest β-carotene content mean were obtained at 2 and 3 M NaCl concentrations, as 1.78×106 cell.ml-1 and 7.40 pg.cell-1, respectively.

The effect of chloramphenicol, actinomycin D and 5-bromouracil on the synthesis of photosynthetic pigments

The present study concerned the effect of chloramphenicol (100 μg/ml), actinomycin D (30 μg/ml), and 5-bromouracil (190 μg/ml) on the accumulation of chlorophyll α, chlorophyll b, β-carotene and four fractions of xanthophylls (with the domination of: lutein, zeaxanthin, violaxanthin and neoxanthin) in the primary bean leaves. The pigment content was determined in etiolated leaves after exposure to light for different lengths of time. It results from this study that chloramphenicol inhibits β-carotene synthesis more than do other pigments. The formation of xanthophylls and chlorophyll b is relatively less sensitive to the action of this antibiotic. Actinomycin D is also a somewhat more effective inhibitor of the accumulation of β-carotene than other pigments. In 5-bromouracil-treated leaves the accumulation of all carotenoids is inhibited almost to the same extent. These results suggest that the accumulation of chlorophyll b and xanthophylls is a little less dependent upon the activity of 70 S ribosomes in chloroplasts than the accumulation of chlorophyll α and β-carotene.

Reproduction and oxidative metabolism in the brooding sea star Anasterias antarctica (Lütken, 1957)

The oral-brooding sea star Anasterias antarctica is distributed on the coasts of South Patagonia and north of Antarctic Peninsula. This species is a potential predator of shellfish Mytilus chilensis, an important commercial resource for Beagle Channel region. The aims of this work were to study the variation in the gonad index (GI), to establish the brooding season, to determine the reproductive effort of both sexes, and to assess the concentration of liposoluble antioxidants and production of reactive oxygen species (ROS) in male and female gonads and embryos of A. antarctica during the year. Four samplings were performed: three during the brooding season and one during the non-brooding season. Individuals sampled during the brooding season were assigned to one of the three groups: brooding females, non-brooding females, and males. Individuals sampled during the non-brooding season were assigned to one of the three groups: sexually mature females, sexually non-mature females and males.Histological observations allowed determining that only females incubate the embryos on the oral surface for seven months. Males showed a strategy characteristic of broadcast spawners, whereas females spawned only a small number of eggs, as it is characteristic of brooders and as observed in other species of asteroids. Males show a significant increase in GI before spawning (from 1% to 15%) and then a marked decrease. During gametogenesis, testes showed a low level of β-carotene and high production of ROS. Between May and October; brooding and non-brooding females showed similar values of ROS production and concentration of antioxidants. Mature females had a significantly higher GI and lipid soluble antioxidant concentration than non-mature females. ROS production was higher in non-mature females. In A. antarctica embryos, ROS production increased and liposoluble antioxidant defenses decreased along development. The reproductive effort of males was about 25% lower than that of females, probably because of brooding costs. Gonadal maturation occurred in summer in both sexes, in concordance with an increase in the concentration of liposoluble antioxidants and the minimum values of ROS production. This suggests a strategy of oxidative damage prevention and gamete protection through allocation of antioxidants to mature gonads. The β-carotene and α-tocopherol accumulation in ovaries would protect not only maturing oocytes but also embryos, given that these antioxidants would be transferred to eggs. Along the reproductive cycle, A. antarctica gonads are protected from oxidative processes, mainly by β-carotene. Further, during gonad maturation, protection increases with the increase in α-tocopherol concentration and the decrease in ROS, whose highest and lowest values coincide with maximum gonadal maturation.

Antioxidant and photoprotective defenses in response to gradual water stress under low and high irradiance in two Malvaceae tree species used for tropical forest restoration

This study provides a mechanistic basis of the tolerance to light and water stress in two tropical tree species of the Malvaceae used for the reforestation in the tropics. G. ulmifolia is more sensitive to high irradiance than C. speciosa . Thus, C. speciosa is more appropriate for the reforestation of degraded areas with potential excess light or water deficit. Reforestation programs in tropics are necessary to mitigate the impacts of climate change, the preservation of biodiversity and for recovery of degraded areas. However, little is known about the abiotic stress tolerance of the major tropical tree species used in reforestation. This study was aimed at evaluating antioxidant defenses and photoprotective pigments against excess light and water deficit in Guazuma ulmifolia Lam. and Ceiba speciosa (A.St.-Hil) Ravenna. Plantlets of 6-month-old were exposed to progressive water deficit by withholding water under high and low irradiance growth conditions and then re-irrigated. G. ulmifolia leaves under high irradiance showed increased photo-oxidative damage, as indicated by a decreased Fv/Fm ratio and 5−12-fold increases in MDA levels, which correlated with a 14-fold increase in SOD activity, a 90 % decrease in POD activity and a 3−4-fold increases in hydrogen peroxide levels. Water deficit combined with high irradiance caused stronger chronic photoinhibition, indicating a synergistic effect that cannot be counterbalanced by antioxidant or photo-protective mechanisms. In contrast, to avoid photo-oxidative damage, C. speciosa enhanced SOD activity, maintained POD and CAT activities, and increased xanthophyll cycle pool size and DPS and β-carotene accumulation. These results indicate that G. ulmifolia is more sensitive to high irradiance than C. speciosa at early stages of development. Thus, C. speciosa is more appropriate for the reforestation of degraded areas with potential excess light or water deficit. In conclusion, this study provides a mechanistic basis of the tolerance abiotic stress in two tropical trees, thereby contributing for management strategies in reforestation projects.

The 2-C-methylerythritol 4-phosphate pathway in melon is regulated by specialized isoforms for the first and last steps.

The 2-C-methyl-d-erythritol-4-phosphate (MEP) pathway provides the precursors for the biosynthesis of plastidial isoprenoids, which include the carotenoid pigments of many fruits. We have analysed the genes encoding the seven enzymes of the MEP pathway in melon (Cucumis melo L.) and determined that the first one, 1-deoxyxylulose 5-phosphate synthase (DXS), and the last one, 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase (HDR), are represented in the genome as a small gene family and paralogous pair, respectively. In the case of DXS, three genes encode functional DXS activities which fall into previously established type I (CmDXS1) and II (CmDXS2a and CmDXS2b) categories, while a fourth DXS-like gene belonging to the type III group did not encode a protein with DXS activity. Their expression patterns and phylogenies suggest that CmDXS1 is functionally specialized for developmental and photosynthetic processes, while CmDXS2a and CmDXS2b are induced in flowers and ripening fruit of orange- (but not white-) fleshed varieties, coinciding with β-carotene accumulation. This is the first instance connecting type II DXS genes to specialized isoprenoid biosynthesis in the fruit of an agronomically important species. Two HDR paralogues were shown to encode functional enzymes, although only CmHDR1 was highly expressed in the tissues and developmental stages tested. Phylogenetic analysis showed that in cucurbits such as melon, these HDR paralogues probably arose through individual gene duplications in a common angiosperm ancestor, mimicking a prior division in gymnosperms, while other flowering plants, including apple, soy, canola, and poplar, acquired HDR duplicates recently as homoeologues through large-scale genome duplications. We report the influence of gene duplication history on the regulation of the MEP pathway in melon and the role of specialized MEP-pathway isoforms in providing precursors for β-carotene production in orange-fleshed melon varieties.

Genetic stability developed for β-carotene synthesis in BR29 rice line using dihaploid homozygosity.

Obtaining transgenic crop lines with stable levels of carotenoids is highly desirable. We addressed this issue by employing the anther culture technique to develop dihaploid lines containing genes involved in β-carotene metabolism. First, we used Agrobacterium- mediated transformation to develop primary transgenic plants containing the β-carotene biosynthetic genes, phytoene synthase (psy) and phytoene desaturase (crtI), which were engineered for expression and accumulation in the endosperm. Transgenic plants were recovered by selecting for the expression of the phosphomannose isomerase (pmi) gene. Dihaploid plants in addition to haploid and tetraploid plant were generated from anther cultures of these primary transgenic plants. In addition to anatomical features of stomata, pollen of different ploidy-plants, molecular analyses confirmed the stable integration of the genes in the anther culture-derived dihaploid plants, and the yellow color of the polished seeds indicated the accumulation of carotenoids in the endosperm. High performance liquid chromatography (HPLC) analysis of the carotenoid extract further confirmed the levels of β–carotene accumulation in the endosperms of the transgenic dihaploid rice seeds.

Abiotic stress modifies the synthesis of alpha-tocopherol and beta-carotene in phytoplankton species.

We performed laboratory experiments to investi-gate whether the synthesis of the antioxidants α-tocopherol (vitamin E) and β-carotene in phytoplankton depends on changes in abiotic factors. Cultures of Nodularia spumigena, Phaeodactylum tricornutum, Skeletonema costatum, Dunaliella tertiolecta, Prorocentrum cordatum, and Rhodomonas salina were incubated at different tempe-ratures, photon flux densities and salinities for 48h. We found that abiotic stress, within natural ecological ranges, affects the synthesis of the two antioxidants in different ways in different species. In most cases antioxidant production was stimulated by increased abiotic stress. In P.tricornutumKAC 37 and D.tertiolectaSCCAP K-0591, both good producers of this compound, α-tocopherol accumulation was negatively affected by environmentally induced higher photosystem II efficiency (Fv /Fm ). On the other hand, β-carotene accumulation was positively affected by higher Fv /Fm in N.spumigena KAC 7, P.tricornutum KAC 37, D.tertiolecta SCCAP K-0591 and R.salina SCCAP K-0294. These different patterns in the synthesis of the two compounds may be explained by their different locations and functions in the cell. While α-tocopherol is heavily involved in the protection of prevention of lipid peroxidation in membranes, β-carotene performs immediate photo-oxidative protection in the antennae complex of photosystem II. Overall, our results suggest a high variability in the antioxidant pool of natural aquatic ecosystems, which can be subject to short-term temperature, photon flux density and salinity fluctuations. The antioxidant levels in natural phytoplankton communities depend on species composition, the physiological condition of the species, and their respective strategies to deal with reactive oxygen species. Since α-tocopherol and β-carotene, as well as many other nonenzymatic antioxidants, are exclusively produced by photo-synthetic organisms, and are required by higher trophic levels through dietary intake, regime shifts in the phytoplankton as a result of large-scale environmental changes, such as climate change, may have serious consequences for aquatic food webs.

Carotenoid production by Rhodotorula glutinis YB-252 in solid-state fermentation

Abstract Carotenoids represent a group of valuable molecules for the pharmaceutical, chemical, food and feed industries. In this study, a Plackett–Burman design was used to evaluate the effect of pH, moisture, carbon source, inoculum concentration, time and temperature of incubation and the concentration of inducer. Also, the influence of a metabolic inhibitor of the β-carotene accumulation was tested, demonstrating that a level of 125 ppm permitted the accumulation of lycopene without concomitant production of β-carotene. Results showed that the highest obtained lycopene concentration was 340 mg L−1. Among the parameters evaluated, the inducer concentration, the fermentation time and the percentage of moisture in the system, are factors having a statistically significant effect on carotenoid production by Rhodotorula glutinis YB-252 in solid-state fermentation.

Dissecting the mechanism of Solanum lycopersicum and Solanum chilense flower colour formation

Flowers are the defining feature of angiosperms, and function as indispensable organs for sexual reproduction. Flower colour typically plays an important role in attracting pollinators, and can show considerable variation, even between closely related species. For example, domesticated tomato (S.lycopersicum) has orange/yellow flowers, while the wild relative S.chilense (accession LA2405) has bright yellow flowers. In this study, the mechanism of flower colour formation in these two species was compared by evaluating the accumulation of carotenoids, assessing the expression genes related to carotenoid biosynthetic pathways and observing chromoplast ultrastructure. In S. chilense petals, genes associated with the lutein branch of the carotenoid biosynthetic pathway, phytoene desaturase (PDS), ζ-carotene desaturase (ZDS), lycopene β-cyclase (LCY-B), β-ring hydroxylase (CRTR-B) and ε-ring hydroxylase (CRTR-E), were highly expressed, and this was correlated with high levels of lutein accumulation. In contrast, PDS, ZDS and CYC-B from the neoxanthin biosynthetic branch were highly expressed in S.lycopersicum anthers, leading to increased β-carotene accumulation and hence an orange/yellow colour. Changes in the size, amount and electron density of plastoglobules in chromoplasts provided further evidence of carotenoid accumulation and flower colour formation. Taken together, these results reveal the biochemical basis of differences in carotenoid pigment accumulation and colour between petals and anthers in tomato.

Predictive modeling of β-carotene accumulation by Dunaliella salina as a function of pH, NaCI, and irradiance

Predictive modeling of β-carotene accumulation by Dunaliella salina as a function of NaCI, pH, and irradiance was studied. Modified Logistic, Gompertz, Schnute, Richards, and Stannard models were fitted to describe β-carotene accumulation by the alga under various environmental conditions. Lag time (λ, days), maximum accumulation (A, pg/cell), and the maximum production rate (μ, 1/day) for β-carotene accumulation were calculated by modified Logistic and Gompertz models. Values of λ, A, and μ for β-carotene accumulation varied between 0.26 and 20.14 days, 57.48 to 198.76 pg β-carotene/cell, and 1.80 to 3.68 1/day, respectively. Results revealed that Logistic and Gompertz models could be used to describe the accumulation of β-carotene by D. salina as a function of salt concentrations, pH, and irradiance. The highest asymptotic value was predicted from Logistic and Gompertz models at pH 9.0, 48 kerg/(cm2 s) light intensity, and 20% NaCl concentration.

High-quality lycopene overaccumulation via inhibition of γ-carotene and ergosterol biosyntheses in Blakeslea trispora

A novel method for producing high-quality lycopene from Blakeslea trispora through submerged fermentation is studied. 2-Isopropylimidazole at 300mg/L completely inhibited lycopene cyclase, which limited the accumulation of γ-carotene and β-carotene. 2-Isopropylimidazole also intensified the metabolic flow of lycopene by increasing the expression levels of key enzymes involved in the lycopene synthetic pathway. Ketoconazole at 20mg/L reduced the metabolic flow of ergosterol and increased lycopene content and production by 76.6% and 64.3%, respectively. Lycopene accounted for approximately 96% of the total carotenoids, whereas cis-lycopene accounted for approximately 35% of the total lycopene. The content and nutritional quality of lycopene from B. trispora were higher than those of lycopene from tomatoes. B. trispora is an ideal source of natural lycopene.

Assessment of crtRB1 Polymorphism Associated with Increased β-Carotene Content in Maize (Zea mays L.) Seeds

Breeding for increasing β-carotene levels in maize (Zea mays L.) kernel aims to address the dietary vitamin A deficiency. Due to 3’TE polymorphism, the crtRB1gene (that encodes β -carotene hydroxylase 1) exists in the three allelic forms, viz., 3’TE allele 1 (termed favorable allele, for it favors higher β-carotene accumulation in kernels), 3’TE allele 2 and 3’TE allele 3 (both termed unfavorable alleles, for they do not favor β-carotene accumulation). Here, we aimed to identify maize lines with favorable allele. First, 3’TE polymorphism assay in 210 inbreds revealed that only “UMI 176” had the favorable allele while the rest had the unfavorable alleles, confirming the previous finding that favorable allele is rare in frequency. Second, β-carotene content analysis in 24 inbreds revealed that it varied from 4.5 to 7.92 (μg/g), 0.23 to 2, and 0.42 to 4.22 for lines with allele 1, 2, and 3 respectively, corroborating the previous findings that the presence of favorable allele correlates with higher β-carotene content. In summary, UMI 176 has the favorable allele and had the highest amount of β-carotene content (7.92 μg/g), indicating that it is a promising donor line that can be utilized in β-carotene biofortification breeding.