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Palacios-Rojas, N.

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Palacios-Rojas
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Palacios-Rojas, N.

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Now showing 1 - 10 of 12
  • Investigating genomic prediction strategies for grain carotenoid traits in a tropical/subtropical maize panel
    (Oxford University Press, 2024) LaPorte, M.F.; Suwarno, W.B.; Hannok, P.; Koide, A.; Bradbury, P.; Crossa, J.; Palacios-Rojas, N.; Diepenbrock, C.
    Publication
  • Near-infrared spectroscopy to predict provitamin A carotenoids content in maize
    (MDPI, 2022) Rosales Nolasco, Aldo; Crossa, J.; Cuevas, J.; Cabrera-Soto, L.; Dhliwayo, T.; Ndhlela, T.; Palacios-Rojas, N.
    Publication
  • Estabilidad del rendimiento y calidad de grano y tortilla de nuevos híbridos de maíz con valor agregado para el subtrópico de México
    (SOMEFI, 2018) Vasquez-Carrillo, G.; Preciado-Ortiz, R.E.; Santiago-Ramos, D.; Palacios-Rojas, N.; Terron Ibarra, A.; Hernandez-Calette, A.
    Publication
  • Provitamin A carotenoids in grain reduce aflatoxin contamination of maize while combating vitamin A deficiency
    (Frontiers, 2019) Suwarno, W.B.; Hannok, P.; Palacios-Rojas, N.; Windham, G.L.; Crossa, J.; Pixley, K.V.
    Aflatoxin contamination of maize grain and products causes serious health problems for consumers worldwide, and especially in low- and middle-income countries where monitoring and safety standards are inconsistently implemented. Vitamin A deficiency (VAD) also compromises the health of millions of maize consumers in several regions of the world including large parts of sub-Saharan Africa. We investigated whether provitamin A (proVA) enriched maize can simultaneously contribute to alleviate both of these health concerns. We studied aflatoxin accumulation in grain of 120 maize hybrids formed by crossing 3 Aspergillus flavus resistant and three susceptible lines with 20 orange maize lines with low to high carotenoids concentrations. The hybrids were grown in replicated, artificially-inoculated field trials at five environments. Grain of hybrids with larger concentrations of beta-carotene (BC), beta-cryptoxanthin (BCX) and total proVA had significantly less aflatoxin contamination than hybrids with lower carotenoids concentrations. Aflatoxin contamination had negative genetic correlation with BCX (-0.28, p < 0.01), BC (-0.18, p < 0.05), and proVA (-0.23, p < 0.05). The relative ease of breeding for increased proVA carotenoid concentrations as compared to breeding for aflatoxin resistance in maize suggests using the former as a component of strategies to combat aflatoxin contamination problems for maize. Our findings indicate that proVA enriched maize can be particularly beneficial where the health burdens of exposure to aflatoxin and prevalence of VAD converge with high rates of maize consumption.
    Publication
  • Retention of carotenoids in biofortified maize flour and β-Cryptoxanthin-Enhanced eggs after household cooking
    (American Chemical Society, 2017) Sowa, M.; Jiaoying Yu; Palacios-Rojas, N.; Goltz, S. R.; Howe, J.A.; Davis, C.R.; Rocheford, T.R.; Tanumihardjo, S.A.
    Biofortification of crops to enhance provitamin A carotenoids is a strategy to increase the intake where vitamin A deficiency presents a widespread problem. Heat, light, and oxygen cause isomerization and oxidation of carotenoids, reducing provitamin A activity. Understanding provitamin A retention is important for assessing efficacy of biofortified foods. Retention of carotenoids in high-xanthophyll and high-β-carotene maize was assessed after a long-term storage at three temperatures. Carotenoid retention in high-β-cryptoxanthin maize was determined in muffins, non-nixtamalized tortillas, porridge, and fried puffs made from whole-grain and sifted flour. Retention in eggs from hens fed high-β-cryptoxanthin maize was assessed after frying, scrambling, boiling, and microwaving. Loss during storage in maize was accelerated with increasing temperature and affected by genotype. Boiling whole-grain maize into porridge resulted in the highest retention of all cooking and sifting methods (112%). Deep-fried maize and scrambled eggs had the lowest carotenoid retention rates of 67–78 and 84–86%, respectively.
    Publication
  • High-throughput measurement methodologies for developing nutrient-dense crops
    (African Scholarly Science Communications Trust, 2017) Guild, G.; Parkes, E.; Nutti, M.; Palacios-Rojas, N.; Stangoulis, J.
    With the development of nutrient-dense crops comes the need for analytical methodologies to enable rapid and accurate analysis of the micronutrients of interest. The analysis of provitamin A carotenoids (pVACs) and the minerals iron (Fe) and zinc (Zn) are the focus of this chapter with the considerations and commonly employed methods discussed. When analyzing samples there are various considerations to minimise analyte degradation (in the case of provitamin A) and reduce possible contamination from external sources (for Fe and Zn). Spectroscopic and chromatographic analyses are the most common analysis approaches utilised when screening for carotenoids. Spectroscopic analyses including near-infrared spectroscopy (NIRS) and iCheck are rapid and require minimal samples preparation and provide fast analysis times. The carotenoids present in the sample is dependent on the crop analyzed and resulting number and concentration of carotenoids present will impact the final decision on suitable analysis techniques. For example, in crops with high concentrations of non-pVACs, chromatographic analysis is necessary in order to accurately quantify the micronutrients. This process is able to accurately identify and quantify individual carotenoids, but requires extensive sample preparation and often long chromatographic separation analysis. When analyzing the minerals Fe and Zn, these same techniques are not suitable, but it is still important to ensure careful sample preparation to deliver accurate analytical results. Degradation of these micronutrients is not a concern, however, possible contamination from soil/ dust/ insects can lead to inaccurate results. Commonly employed analysis such as atomic absorption spectroscopy (AAS) and Inductively Coupled Plasma-Optical Emission Spectrometry ICP-OES or Inductively Coupled Plasma-Mass spectrometry (ICP-MS) require sample digestion prior to analysis and highly pure reagents and gases. These techniques are able to analyze multiple elements and have high accuracy and sensitivity but require specialised facilities and highly trained staff. The use of high-throughput analyses to complement these high-accuracy methods include colorimetric and X-ray flourescence (XRF) technologies. These approaches enable much higher throughput with simple sample preparation and enable screening for micronutrient concentration without the need for specialised facilities.
    Publication
  • Carotenoid retention in biofortified maize using different post-harvest storage and packaging methods
    (Elsevier, 2017) Taleon, V.; Mugode, L.; Cabrera-Soto, L.; Palacios-Rojas, N.
    Orange maize is being promoted as a source of provitamin A carotenoids (pVAC) in Zambia. Carotenoid retention in orange maize grains stored in metal silos, multilayer polyethylene and common woven bags, and maize meal packaged in single and multilayer polyethylene bags was evaluated. Significant differences in total pVAC retention were found between grain storage methods (48.1–57.2%) after 6 months of storage. Total pVAC retention in hammer meal (73.1–73.5%) was higher than in breakfast meal (64.3–69.3%) after 4 months of storage; however, no differences in pVAC retention were found between meal types when stored in single and multilayer polyethylene bags. In general, b-cryptoxanthin (bCX) had higher retention than b-carotene (bC). Potential contribution of stored orange maize to the estimated average requirement of children and women was 26.5% and 24.3%, respectively. Orange maize meal can provide significant amounts of provitamin A to diets of Zambians even after 4 months of storage.
    Publication
  • Effects of S1 recurrent selection for provitamin A carotenoid content for three open-pollinated maize cultivars
    (Crop Science Society of America (CSSA), 2014) Dhliwayo, T.; Palacios-Rojas, N.; Crossa, J.; Pixley, K.V.
    Maize (Zea mays L.) cultivars with increased concentrations of provitamin A (proVA) carotenoids can improve the health of millions of consumers who are vitamin A deficient and rely on maize as a staple food. Three open-pollinated maize cultivars (OP C) were subjected to three cycles of S1 recurrent selection for increased proVA concentration. Agronomic performance of Cycles 0, 1, 2, and 3 for each OP C was evaluated using three replications at 10 locations, and changes in proVA concentration were assessed for hand-pollinated grain produced at two sites. Selection resulted in significant (P < 0.01 for 11, and P < 0.05 for 1 occurrence) linear increases of 25 to 67% per cycle for total proVA, 28 to 60% for b-carotene, 18 to 70% for b-cryptoxanthin, and 11 to 46% for zeaxanthin. These findings are especially significant because, in contrast to recent trends, they demonstrate the feasibility of developing proVAenhanced maize while meeting nutritionists’ recommendations not to sacrifice b-cryptoxanthin and zeaxanthin to increase b-carotene concentration in grain. Grain yield increased in one but decreased (P < 0.01) in two of the OP Cs, and we hypothesize that linkage drag associated with proVA-enhancing genes from exotic donor lines may be responsible for the negative trends. We conclude that breeding proVA-enriched maize without sacrificing b-cryptoxanthin and zeaxanthin concentrations is feasible, but that (i) it remains unknown whether such approaches can achieve the high concentrations of proVA reported elsewhere by using marker-assisted selection for genes that favor b-carotene accumulation, and (ii) that grain yield and agronomic performance should be simultaneously selected if useful cultivars are desired.
    Publication
  • Genome‑wide association analysis reveals new targets for carotenoid biofortification in maize
    (Springer, 2015) Suwarno, W.B.; Pixley, K.V.; Palacios-Rojas, N.; Kaeppler, S.M.; Babu, R.
    Genome-wide association analysis in CIMMYT’s association panel revealed new favorable native genomic variations in/nearby important genes such as hydroxylases and CCD1 that have potential for carotenoid biofortification in maize. Abstract Genome-wide association studies (GWAS) have been used extensively to identify allelic variation for genes controlling important agronomic and nutritional traits in plants. Provitamin A (proVA) enhancing alleles of lycopene epsilon cyclase (LCYE) and β-carotene hydroxylase 1 (CRTRB1), previously identified through candidate-gene based GWAS, are currently used in CIMMYT’s maize breeding program. The objective of this study was to identify genes or genomic regions controlling variation for carotenoid concentrations in grain for CIMMYT’s carotenoid association mapping panel of 380 inbred maize lines, using high-density genome-wide platforms with ~476,000 SNP markers. Population structure effects were minimized by adjustments using principal components and kinship matrix with mixed models. Genome-wide linkage disequilibrium (LD) analysis indicated faster LD decay (3.9 kb; r2 = 0.1) than commonly reported for temperate germplasm, and therefore the possibility of achieving higher mapping resolution with our mostly tropical diversity panel. GWAS for various carotenoids identified CRTRB1, LCYE and other key genes or genomic regions that govern rate-critical steps in the upstream pathway, such as DXS1, GGPS1, and GGPS2 that are known to play important roles in the accumulation of precursor isoprenoids as well as downstream genes HYD5, CCD1, and ZEP1, which are involved in hydroxylation and carotenoid degradation. SNPs at or near all of these regions were identified and may be useful target regions for carotenoid biofortification breeding efforts in maize; for example a genomic region on chromosome 2 explained ~16 % of the phenotypic variance for β-carotene independently of CRTRB1, and a variant of CCD1 that resulted in reduced β-cryptoxanthin degradation was found in lines that have previously been observed to have low proVA degradation rates.
    Publication
  • Genetic architecture controlling variation in grain carotenoid composition and concentrations in two maize populations
    (Springer, 2013) Kandianis, C.B.; Stevens. R.; Liu, W.; Palacios-Rojas, N.; Montgomery, K.; Pixley, K.V.; White, W.S.; Rocheford, T.R.
    The genetic basis for the variation in maize grain carotenoid concentrations was investigated in two F2:3 populations, DEexp × CI7 and A619 × SC55, derived from high total carotenoid and high -carotene inbred lines. A comparison of grain carotenoid concentrations from population DEexp × CI7 grown in different environments revealed significantly higher concentrations and greater trait variation in samples harvested from a subtropical environment relative to those from a temperate environment. Genotype by environment interactions was significant for most carotenoid traits. Using phenotypic data in additive, environment-specific genetic models, quantitative trait loci (QTL) were identified for absolute and derived carotenoid traits in each population, including those specific to the isomerization of-carotene. A multivariate approach for these correlated traits was taken, using carotenoid trait principal components (PCs) that jointly accounted for 97 % or more of trait variation. Component loadings for carotenoid PCs were interpreted in the context of known substrate-product relationships within the carotenoid pathway. Importantly, QTL for univariate and multivariate traits were found to cluster in close proximity to map locations of loci involved in methyl-erythritol, isoprenoid and carotenoid metabolism. Several of these genes, including lycopene epsilon cyclase, carotenoid cleavage dioxygenase1 and beta-carotene hydroxylase, were mapped in the segregating populations. These loci exhibited pleiotropic effects on -branch carotenoids, total carotenoid profile and -branch carotenoids, respectively. Our results confirm that several QTL are involved in the modification of carotenoid profiles, and suggest genetic targets that could be used for the improvement of total carotenoid and -carotene in future breeding populations.
    Publication