Formation of heterotic groups and understanding genetic effects in a provitamin a biofortified maize breeding program
Developing biofortified maize cultivars is a viable approach to combat the widespread problem of vitamin A deficiency among people for whom maize is a staple food. To enhance CIMMYT's provitamin A maize breeding efforts, this study: 1) evaluated whether separation of experimental maize lines into groups based on maximizing their molecular-marker-based genetic distances (GD) resulted in heterosis for among-group crosses, 2) assessed genetic effects (general and specific combining ability, GCA and SCA) for grain yield and provitamin A concentrations in hybrids among 21 inbred lines representing the three proposed groups, and 3) assessed the association between grain yield and provitamin A concentrations. The lines were crossed following a partial diallel design resulting in 156 hybrids which were evaluated at four environments with two replications of one-row plots. The first plant in each plot was self-pollinated to produce grain for provitamin A analysis. Significant but small yield advantage of among versus within group crosses (0.47 Mg ha-1 21 , P<0.05) suggested that the groups identified by maximizing GD could be a practicalstarting point for further breeding work to develop useful heterotic groups. Furthermore, the GD-proposed heterotic groups were improved by later revising some line assignments to groups using estimates of SCA effects. GCA effects were significant (P<0.01) for all traits, whereas SCA effects were weak (P<0.05) or not significant for provitamin A carotenoid concentrations, indicating that these were controlled primarily by additive gene action. Grain yield was not significantly correlated with provitamin A
| Main Authors: | , , , , |
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| Format: | Article biblioteca |
| Language: | English |
| Published: |
Crop Science Society of America (CSSA)
2014
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| Subjects: | AGRICULTURAL SCIENCES AND BIOTECHNOLOGY, MAIZE, PROVITAMINS, FOOD FORTIFICATION, GENE EXPRESSION REGULATION, |
| Online Access: | http://hdl.handle.net/10883/3437 |
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