Genetic Analysis of Visually Scored Orange Kernel Color in Maize

Increasing levels of provitamin A carotenoids in maize (Zea mays L.) grain through plant breed - ing has potential to help humans suffering from vitamin A deficiency. In parts of Africa where this deficiency is prevalent, there is a consumer pref - erence for white maize grain and an avoidance of yellow maize grain. White grain has minimal lev - els of carotenoids whereas yellow grain can have appreciable levels of carotenoids. There is a new effort to introduce orange maize that contains high levels of provitamin A, which appears to be a more acceptable color than yellow to consum - ers in Africa. The implementation of this program requires backcross selection to convert African- adapted germplasm with white grain to orange. We conducted a study to assess the heritability of visual scores for relative intensity of orange kernel color and identify genetic markers asso - ciated with orange color across and within 10 families of the maize nested association map - ping population. We found visually scored ker nel color to have a moderately high heritability and identified five common quantitative trait loci (QTL) and six rare QTL for intensity of orange color. Notably, half of them coincided with carot - enoid biosynthetic genes. our results indicate that breeders in Africa, Asia, and throughout the world would have flexibility to select for orange kernel color visually and/or with gene-specific markers. Such selection can be combined with marker-assisted selection efforts to increase provitamin A levels in maize grain.