scholarly journals Provitamin A-biofortified maize consumption increases serum xanthophylls and 13C-natural abundance of retinol in Zambian children

2017 ◽  
Vol 242 (15) ◽  
pp. 1508-1514 ◽  
Author(s):  
Jesse Sheftel ◽  
Bryan M Gannon ◽  
Christopher R Davis ◽  
Sherry A Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Natural Abundance ◽  
Provitamin A ◽  
Dietary Vitamin ◽  
Mongolian Gerbils ◽  
Serum Retinol ◽  
Provitamin A Carotenoids ◽  
Effectiveness Studies ◽  
The Impact ◽  
Β Carotene

Plants that undergo C4 photosynthesis, such as maize, are enriched in the stable isotope of carbon (13C) compared with other dietary plants and foods. Consumption of maize that has been biofortified to contain elevated levels of provitamin A carotenoids (orange maize) increased the abundance of 13C in serum retinol of Mongolian gerbils. We evaluated this method in humans to determine if it has potential for further use in intervention effectiveness studies. A random subset of samples from a two-month randomized controlled feeding trial of rural three- to five-year old Zambian children were used to determine the impact of orange maize intake on serum carotenoid concentrations ( n = 88) and 13C-natural abundance in serum retinol ( n = 77). Concentrations of β-cryptoxanthin (a xanthophyll provitamin A carotenoid) and the dihydroxy xanthophylls lutein and zeaxanthin, which do not have vitamin A activity, were elevated in children consuming orange maize compared with those consuming a white maize control ( P < 0.001), while β-carotene was not different ( P > 0.3). Furthermore, 13C natural abundance was higher after two months’ intervention in the orange maize group compared with the white maize group ( P = 0.049). Predictions made from equations developed in the aforementioned gerbil study estimated that maize provided 11% (2–21%, 95% confidence interval) of the recent dietary vitamin A to these children. These results demonstrate that orange maize is efficacious at providing retinol to the vitamin A pool in children through provitamin A carotenoids, as monitored by the change in 13C enrichment, which was not reflected in serum β-carotene concentrations. Further effectiveness studies in countries who have adopted orange maize should consider determining differences in retinol 13C-enrichment among target groups in addition to profiling serum xanthophyll carotenoids with specific emphasis on zeaxanthin. Impact statement Maize biofortified with provitamin A carotenoids (orange) has been released in some African markets. Responsive and sensitive methods to evaluate dissemination effectiveness are needed. This study investigated methods to evaluate effectiveness of orange maize consumption using serum from Zambian children fed orange maize for two months. Many varieties of orange maize contain higher amounts of the xanthophyll carotenoids in addition to β-carotene compared with typical varieties. This study uniquely showed higher concentrations of the maize xanthophylls lutein, zeaxanthin, and β-cryptoxanthin in children who consumed orange maize compared with white. Furthermore, maize is a C4 plant and is therefore naturally enriched with 13C. Higher 13C was detected in the serum retinol of the orange maize consumers with no change in serum β-carotene concentration suggesting preferential bioconversion to retinol. The combined analyses of serum zeaxanthin specifically and 13C-natural abundance of retinol could prove useful in effectiveness studies between orange maize adopters and non-adopters.

scholarly journals Cassava with enhanced β-carotene maintains adequate vitamin A status in Mongolian gerbils (Meriones unguiculatus) despite substantial cis-isomer content

2009 ◽  
Vol 102 (3) ◽  
pp. 342-349 ◽  
Author(s):  
Julie A. Howe ◽  
Bussie Maziya-Dixon ◽  
Sherry A. Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Vitamin A Deficiency ◽  
Meriones Unguiculatus ◽  
Provitamin A ◽  
Carotenoid Content ◽  
Mongolian Gerbils ◽  
Serum Retinol ◽  
Vitamin A Status ◽  
Isomer Content ◽  
Β Carotene

Efforts to increase β-carotene in cassava have been successful, but the ability of high-β-carotene cassava to prevent vitamin A deficiency has not been determined. Two studies investigated the bioefficacy of provitamin A in cassava and compared the effects of carotenoid content and variety on vitamin A status in vitamin A-depleted Mongolian gerbils (Meriones unguiculatus). Gerbils were fed a vitamin A-free diet 4 weeks prior to treatment. In Expt 1, treatments (ten gerbils per group) included 45 % high-β-carotene cassava, β-carotene and vitamin A supplements (intake matched to high-β-carotene cassava group), and oil control. In Expt 2, gerbils were fed cassava feeds with 1·8 or 4·3 nmol provitamin A/g prepared with two varieties. Gerbils were killed after 4 weeks. For Expt 1, liver vitamin A was higher (P < 0·05) in the vitamin A (1·45 (sd 0·23) μmol/liver), lower in the control (0·43 (sd 0·10) μmol/liver), but did not differ from the β-carotene group (0·77 (sd 0·12) μmol/liver) when compared with the high-β-carotene cassava group (0·69 (sd 0·20) μmol/liver). The bioconversion factor was 3·7 μg β-carotene to 1 μg retinol (2 mol:1 mol), despite 48 % cis-β-carotene [(Z)-β-carotene] composition in cassava. In Expt 2, cassava feed with 4·3 nmol provitamin A/g maintained vitamin A status. No effect of cassava variety was observed. Serum retinol concentrations did not differ. β-Carotene was detected in livers of gerbils receiving cassava and supplements, but the cis-to-trans ratio in liver differed from intake. Biofortified cassava adequately maintained vitamin A status and was as efficacious as β-carotene supplementation in the gerbil model.

scholarly journals Overlapping Vitamin A Interventions with Provitamin A Carotenoids and Preformed Vitamin A Cause Excessive Liver Retinol Stores in Male Mongolian Gerbils

2020 ◽  
Vol 150 (11) ◽  
pp. 2912-2923 ◽  
Author(s):  
Margaret Sowa ◽  
Luciana Mourao ◽  
Jesse Sheftel ◽  
Mikayla Kaeppler ◽  
Gabrielle Simons ◽  
...  
Keyword(s):  
Vitamin A ◽  
Factorial Design ◽  
Scavenger Receptor ◽  
Public Health Problem ◽  
Negative Control ◽  
Provitamin A ◽  
Mongolian Gerbils ◽  
Serum Retinol ◽  
Class B ◽  
Β Carotene

ABSTRACT Background Vitamin A (VA) deficiency is a public health problem in some countries. Fortification, supplementation, and increased provitamin A consumption through biofortification are efficacious, but monitoring is needed due to risk of excessive VA intake when interventions overlap. Objectives Two studies in 28–36-d-old male Mongolian gerbils simulated exposure to multiple VA interventions to determine the effects of provitamin A carotenoid consumption from biofortified maize and carrots and preformed VA fortificant on status. Methods Study 1 was a 2 × 2 × 2 factorial design (n = 85) with high-β-carotene maize, orange carrots, and VA fortification at 50% estimated gerbil needs, compared with white maize and white carrot controls. Study 2 was a 2 × 3 factorial design (n = 66) evaluating orange carrot and VA consumption through fortification at 100% and 200% estimated needs. Both studies utilized 2-wk VA depletion, baseline evaluation, 9-wk treatments, and liver VA stores by HPLC. Intestinal scavenger receptor class B member 1 (Scarb1), β-carotene 15,15′-dioxygenase (Bco1), β-carotene 9′,10′-oxygenase (Bco2), intestine-specific homeobox (Isx), and cytochrome P450 26A1 isoform α1 (Cyp26a1) expression was analyzed by qRT-PCR in study 2. Results In study 1, liver VA concentrations were significantly higher in orange carrot (0.69 ± 0.12 μmol/g) and orange maize groups (0.52 ± 0.21 μmol/g) compared with baseline (0.23 ± 0.069 μmol/g) and controls. Liver VA concentrations from VA fortificant alone (0.11 ± 0.053 μmol/g) did not differ from negative control. In study 2, orange carrot significantly enhanced liver VA concentrations (0.85 ± 0.24 μmol/g) relative to baseline (0.43 ± 0.14 μmol/g), but VA fortificant alone (0.42 ± 0.21 μmol/g) did not. Intestinal Scarb1 and Bco1 were negatively correlated with increasing liver VA concentrations (P &lt; 0.01, r2 = 0.25–0.27). Serum retinol concentrations did not differ. Conclusions Biofortified carrots and maize without fortification prevented VA deficiency in gerbils. During adequate provitamin A dietary intake, preformed VA intake resulted in excessive liver stores in gerbils, despite downregulation of carotenoid absorption and cleavage gene expression.

scholarly journals Relationship of serum carotenoids and retinol with anaemia among pre-school children in the northern mountainous region of Vietnam

2010 ◽  
Vol 13 (11) ◽  
pp. 1863-1869 ◽  
Author(s):  
Nguyen Cong Khan ◽  
Phan Van Huan ◽  
Nguyen Van Nhien ◽  
Le Danh Tuyen ◽  
Saskia de Pee ◽  
...  
Keyword(s):  
Vitamin A ◽  
School Children ◽  
Vitamin A Deficiency ◽  
Geometric Mean ◽  
Provitamin A ◽  
Mountainous Region ◽  
Serum Retinol ◽  
Provitamin A Carotenoids ◽  
Serum Carotenoids ◽  
Β Carotene

AbstractObjectiveTo characterize the relationship between serum carotenoids, retinol and anaemia among pre-school children.DesignA cross-sectional study was conducted in two groups: anaemic and non-anaemic. Serum levels of retinol, α-carotene, β-carotene, β-cryptoxanthin, lycopene, lutein and zeaxanthin were measured in the study subjects.SettingSix rural communes of Dinh Hoa, a rural and mountainous district in Thai Nguyen Province, in the northern mountainous region of Vietnam.SubjectsA total of 682 pre-school children, aged 12–72 months, were recruited.ResultsGeometric mean serum concentrations of carotenoids (μmol/l) were 0·056 for α-carotene, 0·161 for β-carotene, 0·145 for β-cryptoxanthin, 0·078 for lycopene, 0·388 for lutein and 0·075 for zeaxanthin. The mean levels of Hb and serum retinol were 108·8 g/l and 1·02 μmol/l, respectively. The prevalence of anaemia and vitamin A deficiency was 53·7 % and 7·8 %, respectively. After adjusting for sex and stunting, serum retinol concentrations (μmol/l; OR = 2·06, 95 % CI 1·10, 3·86, P = 0·024) and total provitamin A carotenoids (μmol/l; OR = 1·52, 95 % CI 1·01, 2·28, P = 0·046) were independently associated with anaemia, but non-provitamin A carotenoids (μmol/l; OR = 0·93, 95 % CI 0·63, 1·37, P = 0·710) were not associated with anaemia.ConclusionsAmong pre-school children in the northern mountainous region of Vietnam, the prevalences of vitamin A deficiency and anaemia are high, and serum retinol and provitamin A carotenoids are independently associated with anaemia. Further studies are needed to determine if increased consumption of provitamin A carotenoids will reduce anaemia among pre-school children.

scholarly journals Small quantities of carotenoid-rich tropical green leafy vegetables indigenous to Africa maintain vitamin A status in Mongolian gerbils (Meriones unguiculatus)

2010 ◽  
Vol 103 (11) ◽  
pp. 1594-1601 ◽  
Author(s):  
Richard A. Ejoh ◽  
Joseph T. Dever ◽  
Jordan P. Mills ◽  
Sherry A. Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Hibiscus Cannabinus ◽  
Leafy Vegetables ◽  
Provitamin A ◽  
Control Group ◽  
Mongolian Gerbils ◽  
Retinyl Acetate ◽  
Provitamin A Carotenoids ◽  
Vitamin A Status ◽  
Β Carotene

Leafy vegetables are important sources of provitamin A carotenoids. Information on their ability to provide vitamin A is often misleading because of the methodology used to assess bioefficacy. Mongolian gerbils were used to evaluate the bioefficacy of provitamin A carotenoids in tropical leafy vegetables (i.e. Solanum nigrum, Moringa oleifera, Vernonia calvoana and Hibiscus cannabinus) that are indigenous to Africa. Gerbils (n 67) were vitamin A-depleted for 5 weeks. After a baseline kill (n 7), the gerbils were weight-matched and assigned to six treatment groups (n 10; four vegetable groups; negative and positive controls). For 4 weeks, the treatments included 35 nmol vitamin A (theoretical concentrations based on 100 % bioefficacy) in the form of vegetables or retinyl acetate. In addition to their diets, the control and vegetable groups received daily doses of oil, while the vitamin A group received retinyl acetate in oil matched to prior day intake. Serum and livers were analysed for vitamin A using HPLC. Serum retinol concentrations did not differ among groups, but total liver vitamin A of the vitamin A and vegetable groups were higher than that of the negative control group (P < 0·0001). Liver β-carotene 15,15′-monooxygenase-1 expression levels were determined for two vegetable groups and were similar to the positive and negative controls. Conversion factors for the different leafy vegetables were between 1·9 and 2·3 μg β-carotene equivalents to 1 μg retinol. Small quantities of these vegetables maintained vitamin A status in gerbils through efficient bioconversion of β-carotene to retinol.

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

scholarly journals Relative vitamin A values of 9-cis- and 13-cis-β-carotene do not differ when fed at physiological levels during vitamin A depletion in Mongolian gerbils (Meriones unguiculatus)

2014 ◽  
Vol 112 (2) ◽  
pp. 162-169 ◽  
Author(s):  
Kara A. Bresnahan ◽  
Christopher R. Davis ◽  
Sherry A. Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Experimental Studies ◽  
Meriones Unguiculatus ◽  
Mongolian Gerbils ◽  
Plant Foods ◽  
Depletion Period ◽  
Oral Doses ◽  
The Impact ◽  
Β Carotene

Provitamin A biofortification of staple crops may decrease the prevalence of vitamin A (VA) deficiency if widely adopted in target countries. To assess the impact of processing methods on the VA value of plant foods, the unique bioefficacies ofcis-βC isomers (formed during cooking) compared with all-trans(at) β-carotene (βC) must be determined. The bioefficacies of 9-cis(9c)- and 13-cis(13c)-βC isomers were compared with those of the at-βC isomer and VA positive (VA+) and negative (VA − ) controls in VA-depleted Mongolian gerbils (Meriones unguiculatus) in two experimental studies (study 1,n56; study 2,n57). A 3- or 4-week depletion period was followed by a 3- or 4-week treatment period in which the groups received oral doses of the 9c-, 13c- or at-βC isomers in cottonseed oil (study 1, 15 nmol/d; study 2, 30 nmol/d). In study 1, the βC isomers did not maintain baseline liver VA stores in all groups (0·69 (sd0·20) μmol/liver) except in the VA+group (0·56 (sd0·10) μmol/liver) (P= 0·0026). The βC groups were similar to the VA+group, but the 9c- and 13c-βC groups did not differ from the VA − group (0·39 (sd0·09) μmol/liver). In study 2, the βC isomers maintained baseline liver VA stores in all the βC groups (0·35 (sd0·13) μmol/liver), and in the VA+group, the VA supplement (0·54 (sd0·19) μmol/liver) exceeded the baseline VA status (0·38 (sd0·15) μmol/liver) (P< 0·0001); however, the 9c-βC group did not differ from the VA − group (0·20 (sd0·07) μmol/liver).In vivoisomerisation of βC was confirmed in both experimental studies. Lower VA bioconversion factor values were obtained for thecis-βC isomers in study 2 when compared with study 1, but higher values were obtained for the at-βC isomer. Dose and VA status clearly affect bioconversion factors. In conclusion, thecis-βC isomers yielded similar liver VA stores to the at-βC isomer in Mongolian gerbils, and liver VA stores of the 9c- and 13c-βC groups did not differ when the doses were provided at physiological levels over time in two studies.

scholarly journals Anthocyanin and Lycopene Content Do Not Affect Beta-Carotene Bioefficacy from Multicolored Carrots in Male Mongolian Gerbils

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 110-110
Author(s):  
Mikayla Kaeppler ◽  
Jordan Smith ◽  
Christopher Davis ◽  
Philipp Simon ◽  
Sherry Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Public Health Problem ◽  
Negative Control Group ◽  
Negative Control ◽  
Provitamin A ◽  
Control Group ◽  
Anthocyanin Content ◽  
Mongolian Gerbils ◽  
Serum Retinol ◽  
Freeze Dried

Abstract Objectives Increasing provitamin A carotenoid consumption is one way to combat vitamin A (VA) deficiency, which is a public health problem in various countries. Multicolored carrots contain provitamin A carotenoids as well as other bioactive phytochemicals, such as anthocyanins and lycopene. Two studies in male Mongolian gerbils were conducted to assess the bioefficacy of β-carotene (BC) with simultaneous consumption of anthocyanins and lycopene from multicolored carrots. Methods In Study 1 (n = 65), BC bioefficacy was compared in gerbils fed diets with a range of lycopene concentrations, sourced from freeze-dried red carrots. Study 2 (n = 66) utilized purple red carrots to create diets with varying anthocyanin content. Each study included positive and negative control groups (n = 10/group) fed white carrot VA-free feeds. Each study included 3-wk VA-depletion, baseline evaluation in 5 or 6 gerbils, and 4-wk treatment periods with 10 gerbils/treatment. HPLC analysis of liver VA stores and serum VA were performed. Results In Study 1, there were no differences among groups. These results may have been influenced by an unanticipated high variation in gerbil starting weight, which was correlated to their final hepatic VA stores. In Study 2, vitamin A liver stores (0.21 ± 0.08 μmol/g) of the treatment groups did not differ from baseline (0.23 ± 0.06 μmol/g) or the positive control group (0.22 ± 0.08 μmol/g), but all groups significantly differed from the negative control group (0.11 ± 0.07μmol/g). Serum retinol concentrations did not correlate with the hepatic VA stores in either study. Conclusions These results confirm previous studies that BC is bioavailable from purple red carrots. The results from Study 2, suggest that simultaneous consumption of carotenoids and anthocyanins do not impact the relative bioavailability of BC. These results add more evidence that serum VA concentrations do not accurately represent hepatic VA stores at deficient to normal concentrations. Funding Sources California Fresh Carrot Advisory Board and the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2016–51,181-25,400 (PWS).

scholarly journals β-Cryptoxanthin from supplements or carotenoid-enhanced maize maintains liver vitamin A in Mongolian gerbils (Meriones unguiculatus) better than or equal to β-carotene supplements

2008 ◽  
Vol 100 (4) ◽  
pp. 786-793 ◽  
Author(s):  
Christopher Davis ◽  
Hua Jing ◽  
Julie A. Howe ◽  
Torbert Rocheford ◽  
Sherry A. Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Cottonseed Oil ◽  
Meriones Unguiculatus ◽  
Mongolian Gerbils ◽  
Institute Of Medicine ◽  
Retinyl Acetate ◽  
Provitamin A Carotenoids ◽  
And Control ◽  
Β Carotene ◽  
Better Than

Maize with enhanced provitamin A carotenoids (biofortified), accomplished through conventional plant breeding, maintains vitamin A (VA) status in Mongolian gerbils (Meriones unguiculatus). Two studies in gerbils compared the VA value of β-cryptoxanthin with β-carotene. Study 1 (n 47) examined oil supplements and study 2 (n 46) used maize with enhanced β-cryptoxanthin and β-carotene. After 4 weeks' depletion, seven or six gerbils were killed; remaining gerbils were placed into weight-matched groups of 10. In study 1, daily supplements were cottonseed oil, and 35, 35 or 17·5 nmol VA (retinyl acetate), β-cryptoxanthin or β-carotene, respectively, for 3 weeks. In study 2, one group of gerbils was fed a 50 % biofortified maize diet which contained 2·9 nmol β-cryptoxanthin and 3·2 nmol β-carotene/g feed. Other groups were given equivalent β-carotene or VA supplements based on prior-day intake from the biofortified maize or oil only for 4 weeks. In study 1, liver retinol was higher in the VA (0·74 (sd 0·11) μmol) and β-cryptoxanthin (0·65 (sd 0·10) μmol) groups than in the β-carotene (0·49 (sd 0·13) μmol) and control (0·41 (sd 0·16) μmol) groups (P < 0·05). In study 2, the VA (1·17 (sd 0·19) μmol) and maize (0·71 (sd 0·18) μmol) groups had higher liver retinol than the control (0·42 (sd 0·16) μmol) group (P < 0·05), whereas the β-carotene (0·57 (sd 0·21) μmol) group did not. Bioconversion factors (i.e. 2·74 μg β-cryptoxanthin and 2·4 μg β-carotene equivalents in maize to 1 μg retinol) were lower than the Institute of Medicine values.

scholarly journals 13 C Natural Abundance of Serum Retinol is a Novel Biomarker for Evaluating Effectiveness of Provitamin A Biofortified Maize and Carrots in Male Mongolian Gerbils

2016 ◽  
Vol 30 (S1) ◽  
Author(s):  
Bryan M Gannon ◽  
India Pungarcher ◽  
Luciana Mourao ◽  
Christopher R Davis ◽  
Phillip M Simon ◽  
...  
Keyword(s):  
Natural Abundance ◽  
Provitamin A ◽  
Mongolian Gerbils ◽  
Serum Retinol

scholarly journals Characterization of cassava ORANGE proteins and their capability to increase provitamin A carotenoids accumulation

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0262412
Author(s):  
Angélica M. Jaramillo ◽  
Santiago Sierra ◽  
Paul Chavarriaga-Aguirre ◽  
Diana Katherine Castillo ◽  
Anestis Gkanogiannis ◽  
...  
Keyword(s):  
Vitamin A ◽  
Vitamin A Deficiency ◽  
Protein Characterization ◽  
Provitamin A ◽  
Carotenoid Content ◽  
Dietary Vitamin ◽  
Crystal Formation ◽  
Biosynthesis Pathway ◽  
Provitamin A Carotenoids

Cassava (Manihot esculenta Crantz) biofortification with provitamin A carotenoids is an ongoing process that aims to alleviate vitamin A deficiency. The moderate content of provitamin A carotenoids achieved so far limits the contribution to providing adequate dietary vitamin A levels. Strategies to increase carotenoid content focused on genes from the carotenoids biosynthesis pathway. In recent years, special emphasis was given to ORANGE protein (OR), which promotes the accumulation of carotenoids and their stability in several plants. The aim of this work was to identify, characterize and investigate the role of OR in the biosynthesis and stabilization of carotenoids in cassava and its relationship with phytoene synthase (PSY), the rate-limiting enzyme of the carotenoids biosynthesis pathway. Gene and protein characterization of OR, expression levels, protein amounts and carotenoids levels were evaluated in roots of one white (60444) and two yellow cassava cultivars (GM5309-57 and GM3736-37). Four OR variants were found in yellow cassava roots. Although comparable expression was found for three variants, significantly higher OR protein amounts were observed in the yellow varieties. In contrast, cassava PSY1 expression was significantly higher in the yellow cultivars, but PSY protein amount did not vary. Furthermore, we evaluated whether expression of one of the variants, MeOR_X1, affected carotenoid accumulation in cassava Friable Embryogenic Callus (FEC). Overexpression of maize PSY1 alone resulted in carotenoids accumulation and induced crystal formation. Co-expression with MeOR_X1 led to greatly increase of carotenoids although PSY1 expression was high in the co-expressed FEC. Our data suggest that posttranslational mechanisms controlling OR and PSY protein stability contribute to higher carotenoid levels in yellow cassava. Moreover, we showed that cassava FEC can be used to study the efficiency of single and combinatorial gene expression in increasing the carotenoid content prior to its application for the generation of biofortified cassava with enhanced carotenoids levels.

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