Diallel Analysis of Resistance to Fusarium Ear Rot and Fumonisin Contamination in Maize

The fungus Fusarium verticillioides infects maize (Zea mays L.) ears and kernels, resulting in Fusarium ear rot disease, reduced grain yields, and contamination of grain with the mycotoxin fumonisin. Hybrid maize breeding programs involve selection for both inbred and hybrid performance; the emphasis placed on inbred versus hybrid selection depends on heritability of and the genetic correlation between resistance in the different generations. The objectives of this study were to assess the importance of general combing ability (GCA) and specifi c combining ability (SCA) for resistance to Fusarium ear rot and fumonisin contamination and to estimate the correlation between resistance measured in inbred and hybrid generations. We evaluated a diallel mating of 18 inbred lines from different heterotic groups with different levels of resistance. Hybrids had 27% less ear rot and 30% less fumonisin content than their inbred parents, demonstrating the importance of hybrid vigor to disease resistance. Both GCA and SCA were signifi cant for yield and disease resistance, and inbred performance per se and corresponding GCA in hybrids were signifi cantly correlated (r ≥ 0.78). Genetic variation for resistance was greater in inbred lines than among hybrids, however. These results suggest that the most effi cient way to improve Fusarium ear rot and fumonisin contamination resistances in hybrids is to evaluate and select among inbred lines before using resources to create and evaluate hybrids. H.-Y. Hung and J.B. Holland, Dep. of Crop Science, North Carolina State Univ. Campus Box 7620, Raleigh, NC 27695; J.B. Holland, U.S. Department of Agriculture–Agricultural Research Service (USDAARS). Received 6 Mar. 2012. *Corresponding author ( james_holland@ ncsu.edu). Abbreviations: GCA, general combining ability; LNFUM, natural log transformation of fumonisin content; LNROT, natural log transformation of Fusarium ear rot percentage; SCA, specifi c combining ability. Published in Crop Sci. 52:2173–2181 (2012). doi: 10.2135/cropsci2012.03.0154 © 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.