2596 WWW.CROPS.ORG CROP SCIENCE, VOL. 54, NOVEMBER– DECEMBER 2014 RESEARCH N et blotch ( Pyrenophora teres ) is one of the most widespread foliar diseases of barley (Hordeum vulgare L.), occurring in most regions where barley is grown. Net blotch epidemics can cause yield losses ranging from a trace to 100%, but typically cause losses from 10 to 40% (Mathre, 1997). The disease occurs in two forms: Pyrenophora teres f. teres Smedeg. causes the net-type of net blotch (NTNB) and P. teres f. maculata Smed.-Pet. causes the spot-type of net blotch (STNB). The NTNB-causing isolates have been reported as more virulent than STNB-causing isolates (Wu et al., 2003). Resistance to NTNB has been characterized in several studies. The NTNB resistance genes Rpt1a, Rpt3d, Rpt1b, and Rpt2c were assigned to barley chromosomes 3H, 2H, 3H, and 5H, respectively, using trisomic analysis (Bockelman et al., 1977). The donor par- ents of these resistance genes are ‘Tifang’ (PI 69426, Rpt1a), CIho Mapping Net Blotch Resistance in ‘Nomini’ and CIho 2291 Barley P. D. O’Boyle,* W. S. Brooks, M. D. Barnett, G. L. Berger, B. J. Stefenson, E. L. Stromberg, M. A. Saghai Maroof, S.Y. Liu, and C. A. Gri fey ABSTRACT Net blotch (Pyrenophora teres) is one of the most devastating diseases of barley (Hordeum vulgare L.) worldwide. Identifcation of diagnos- tic molecular markers associated with genes and quantitative trait loci (QTL) for net blotch resistance will facilitate pyramiding of indepen- dent genes. Linkage mapping was used to iden- tify chromosomal locations of the independent, dominant genes conditioning net blotch resis- tance in the winter barley ‘Nomini’ (PI 566929) and spring barley CIho 2291. The F 2 populations of 238 and 193 individuals, derived from crosses between the susceptible spring barley parent ‘Hector’ (CIho 15514) and the resistant parents Nomini and CIho 2291, respectively, were used to map the genes governing resistance in the resistant parents. The dominant gene governing resistance in Nomini, temporarily designated Rpt-Nomini , was mapped to a 9.2-cM region of barley chromosome 6H between the fank- ing microsatellite markers Bmag0344a (r 2 = 0.7) and Bmag0103a (r 2 = 0.9), which were 6.8 and 2.4 cM away from Rpt-Nomini , respectively. The dominant gene governing resistance in CIho 2291, temporarily designated Rpt-CIho2291 , was mapped to a 34.3-cM interval on the dis- tal region of barley chromosome 6H between the fanking microsatellite markers Bmag0173 (r 2 = 0.65) and Bmag0500 (r 2 = 0.26), which were 9.9 and 24.4 cM away from Rpt-CIho2291 , respectively. Identifcation of the chromosomal location of Rpt-Nomini and Rpt-CIho2291 will facilitate efforts in pyramiding multiple genes for net blotch resistance. P.D. O’Boyle, Betaseed, Inc., Shakopee, MN 55379; W.S. Brooks, M.D. Barnett, M.A. Saghai Maroof, S.Y. Liu, and C.A. Gri fey, Dep. of Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA 24061; S.Y. Liu, current address: Texas AgriLife Research, Texas A&M Univ., 6500 Amarillo Blvd. West, Amarillo, TX 79106; G.L. Berger, Dep. of Crop, Soil, and Environmental Sciences, Univ. of Arkansas, Rice Research and Extension Center, Stuttgart, AR 72160; B.J. Stef- fenson, Dep. of Plant Pathology, Univ. of Minnesota, St. Paul, MN 55108; E.L. Stromberg, Dep. of Plant Pathology, Physiology, and Weed Sciences, Virginia Tech, Blacksburg, VA 24061. Received 1 Aug. 2013. *Corresponding author (poboyle@betaseed.com). Abbreviations: BSA, bulked segregant analysis; DH, doubled haploid; MAS, marker-assisted selection; NTNB, net-type net blotch; PCR, polymerase chain reaction; QTL, quantitative trait loci; SSR, simple sequence repeat or microsatellite marker; STNB, spot-type net blotch. Published in Crop Sci. 54:2596–2602 (2014). doi: 10.2135/cropsci2014.08.0514 © 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. Published May 15, 2015 CORE Metadata, citation and similar papers at core.ac.uk Provided by University of Minnesota Digital Conservancy