Effects of S1 recurrent selection for provitamin A carotenoid content for three open-pollinated maize cultivars
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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