Molecular Mapping of Wheat Leaf Rust Resistance Gene Lr42

Leaf rust, caused by Puccinia triticina Eriks., is an important foliar disease of wheat (Triticum aestivum L.) worldwide. Leaf rust resistance gene Lr42 from Aegilops tauschii Coss. has been used as a source of rust resistance in breeding programs. To identify molecular markers closely linked to Lr42, a segregating population of nearisogenic lines contrasting for the presence of Lr42 was developed in the hard winter wheat cultivar Century background and evaluated for rust infection type at both seedling and adult-plant stages. Simple sequence repeat (SSR) markers were screened using bulked-segregant analysis. Two markers closely linked to Lr42 were identifi ed on chromosome 1DS. The closest marker, Xwmc432, is about 0.8 cM from Lr42. Physical mapping of both SSR markers using Chinese Spring nullitetrasomic and ditelosomic genetic stocks confi rmed that the markers linked to Lr42 were on 1DS. Markers for Lr42 were highly polymorphic between parents and among a diverse set of wheat germplasm collected from several countries, indicating that these markers are useful for marker-assisted selection for Lr42. X. Sun, Dep. of Agronomy, Kansas State Univ., Manhattan KS 66506; G. Bai and R. Bowden, USDA-ARS, Hard Winter Wheat Genetics Research Unit, Manhattan, KS 66506; B.F. Carver, Dep. of Plant and Soil Sciences, Oklahoma State Univ., Stillwater, OK 74078. Received 27 Jan. 2009. *Corresponding author ([email protected]). Abbreviations: IT, infection type; MAS, marker-assisted selection; NIL, near-isogenic line; PCR, polymerase chain reaction; SSR, simple sequence repeat. Published in Crop Sci. 50:59–66 (2010). doi: 10.2135/cropsci2009.01.0049 © 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.