Molecular Markers for Leaf Rust Resistance Gene Lr42 in Wheat

Wheat leaf rust, caused by Puccinia triticina Eriks., is an important wheat (Triticum aestivum L.) foliar disease worldwide. Growing cultivars incorporating genetic resistance is one of the most effective approaches for disease control. Leaf rust resistance gene Lr42 was identified from a wheat relative, Aegilops tauschii Coss. (goatgrass), and has been transferred into hard winter wheat. A previous study identified two markers closely linked to the gene on the short arm of chromosome 1D (1DS) using a near-isogenic population, but flanking markers for Lr42 were not found. In this study, a new mapping population was developed from a cross between ‘KS93U50’ (a Lr42 carrier) and a susceptible parent, ‘Morocco’. An F2 population was analyzed with all simple sequence repeat (SSr) markers available from chromosome 1D and F2 plants and F3 families were evaluated for seedling resistance to isolate pNMrJ, a rust isolate avirulent to Lr42. The F2 and F3 rust data showed that Lr42 was recessive. Seven markers formed the linkage group on chromosome 1DS. The Lr42 region was flanked by two SSr markers, Xwmc432 and Xgdm33, at 18 cM apart. The results confirmed that Lr42 is positioned on the distal end of chromosome 1DS. The flanking markers for Lr42 should be useful for mapbased cloning and marker-assisted pyramiding of Lr42 with other leaf rust resistance genes. Z. Liu, Institute of Millet Crops, Hebei Academy of Agricultural & Forestry Sciences, Shijiazhuang, Hebei, 050031 China; Z. Liu and G. Bai, Dep. of Agronomy, Kansas State Univ.; R. L. Bowden and G. Bai, USDA-ARS, Hard Winter Wheat Genetics Research Unit, Manhattan, KS 66506. Received 13 Sept. 2012. *Corresponding author ([email protected]). Abbreviations: IT, infection type; MAS, marker-assisted selection; PCR, polymerase chain reaction; SSR, simple sequence repeat. Published in Crop Sci. 53:1566–1570 (2013). doi: 10.2135/cropsci2012.09.0532 © 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.