Molecular Characterization of Maize Inbreds with Expired U.S. Plant Variety Protection

Maize inbred lines with expired Plant Variety Protection Act (PVPA) certifi cates are publicly available and potentially represent a new germplasm resource for many public and private breeding programs. However, accurate pedigree and genetic background information for ex-PVPA maize inbreds is necessary if they are to be effectively utilized in breeding efforts. We have used single nucleotide polymorphism (SNP) markers to evaluate the relationships and population structure among 92 ex-PVPA inbred lines in relation to 17 well-known public inbreds. Based on unweighted pair group method with arithmetic mean clustering, principal components analysis, and model-based clustering, we identifi ed six primary genetic clusters represented by the prominent inbred lines B73, Mo17, PH207, A632, Oh43, and B37. We also determined the genetic background of ex-PVPA inbreds with confl icting, ambiguous, or undisclosed pedigrees. We assessed genetic diversity across subsets of ex-PVPA lines and concluded that the ex-PVPA lines are no more diverse than the public set evaluated here. Additionally, all alleles present in the ex-PVPA inbreds, for the 614 SNPs included in this study, are also found in public temperate maize germplasm. P.T. Nelson, N.D. Coles, and M.M. Goodman, Dep. of Crop Science, North Carolina State Univ., Box 7620, Raleigh, NC 27695; J.B. Holland, USDA-ARS, Plant Science Research Unit, Dep. of Crop Science, North Carolina State Univ., Raleigh, NC 27695-7620; D.M. Bubeck and S. Smith, Pioneer Hi-Bred International, Inc., Crop Genetics Research and Product Development, DuPont Agriculture and Nutrition, 7300 NW 62nd Ave., Box 1004, Johnston, IA 50131-1004. Received 13 Feb. 2008. *Corresponding author ([email protected]). Abbreviations: DK, DEKALB Genetics; GEM, Germplasm Enhancement of Maize; LH, Holden’s Foundation Seeds; NK, Novartis Seeds; PCA, principal components analysis; PH, Pioneer Hi-Bred International Inc.; PVPA, Plant Variety Protection Act; SNP, single nucleotide polymorphism; UPGMA, unweighted pair group method with arithmetic mean. Published in Crop Sci. 48:1673–1685 (2008). doi: 10.2135/cropsci2008.02.0092 © Crop Science Society of America 677 S. Segoe 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.