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Pixley, K.V.

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Pixley
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K.V.
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Pixley, K.V.

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  • 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.
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  • 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.
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