CROP SCIENCE, VOL. 53, JANUARY– FEBRUARY 2013 WWW.CROPS.ORG 189 RESEARCH F or millions of people in developing countries, plant products with dietary provitamin A carotenoids such as b -carotene, b -cryptoxanthin, and a-carotene are the major source of vitamin A (West and Darnton-Hill, 2008). Within these countries, insuf- icient provitamin A or vitamin A content in diets is a major cause Genetic Analysis of Visually Scored Orange Kernel Color in Maize Kristin Chandler, Alexander E. Lipka, Brenda F. Owens, Huihui Li, Edward S. Buckler, Torbert Rocheford,* and Michael A. Gore* ABSTRACT 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 deiciency. In parts of Africa where this deiciency 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 identiied ive 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 lexibility to select for orange kernel color visually and/or with gene-speciic markers. Such selection can be combined with marker-assisted selection efforts to increase provitamin A levels in maize grain. K. Chandler, B. Owens, and T. Rocheford, Department of Agronomy, Purdue University, West Lafayette, IN; A.E. Lipka, USDA-ARS, Robert W. Holley Center for Agriculture and Health, Ithaca, NY; H. Li, Institute of Crop Science, The National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, Beijing, China; E.S. Buckler, USDA-ARS, Robert W. Holley Center for Agriculture and Health, Institute for Genomic Diversity, Department of Plant Breeding and Genetics, Cornell University, Ithaca, NY; M.A. Gore, USDA-ARS, U.S. Arid Land Agricultural Research Center, Maricopa, AZ; Current Address: K. Chandler, Pioneer, Hi-Bred International, Inc., 4200 West Service Road, Unit 4, Evans, CO 80620. K. Chandler and A.E. Lipka contributed equally to this work. *Corresponding authors (Torbert@purdue.edu; Michael.Gore@ ars.usda.gov). Abbreviations: AR1, irst-order autoregressive; BLUP, best lin- ear unbiased predictor; CCD, carotenoid cleavage dioxygenase; FDR, false discovery rate; 2 ˆ C h , heritability across the entire experiment; 2 ˆ l h , heritability on a line-mean basis across all nested association mapping families; 2 ˆ p lw h , heritability on a line-mean basis within only the pth nested association mapping family; 2 ˆ p h , heritability on an individual plot basis across all nested association mapping families; MAS, marker-assisted selection; NAM, nested association mapping; PVE, phenotypic variance explained; Q×E, quantitative trait loci × environment; QTL, quantita- tive trait loci/locus; RIL, recombinant inbred line; SNP, single nucleo- tide polymorphism; ZEP, zeaxanthin epoxidase. Published in Crop Sci. 53:189–200 (2013). doi: 10.2135/cropsci2012.02.0129 © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.