CROP SCIENCE, VOL. 50, SEPTEMBER– OCTOBER 2010 1831 RESEARCH S temphyliam blight is a serious threat to lentil cultivation in some parts of the world, especially in South Asia including Bangladesh, Northeast India, and Nepal. This disease has also been reported in Egypt, Syria, and North America (Erskine and Sarker, 1997, p. 8–9; Bayaa and Erskine, 1998; ICARDA, 2004; Banniza, 2005). The dis- ease results in yield losses that exceed 60% in severely infected felds. Historically it has been considered a disease of minor importance in the U.S. northern plains (Montana and North Dakota) and in Saskatchewan, Canada, but with the increase of lentil production and deployment of new cultivars with resistance to ascochyta blight (caused by Ascochyta rabiei Pass. Lab) and anthracnose [caused by Col- letotrichum truncatum (Schwein.) Andrus and Moore], stemphylium blight has become a more serious problem (Banniza, 2005). The pathogen has a wide geographic distribution and infects plants in 43 genera. The diverse host range of S. botryosum, which includes leguminous and nonleguminous species in diferent parts of the world, demonstrates its adaptability to diferent genotypes and environments (du Toit and Derie, 2001). Symptoms of disease start as pinhead-sized light brown or colored spots on leafets of plants in Inheritance and Linkage Map Positions of Genes Conferring Resistance to Stemphylium Blight in Lentil Gopesh C. Saha,* Ashutosh Sarker, Weidong Chen, George J. Vandemark, and Fred J. Muehlbauer ABSTRACT Stemphylium blight (caused by Stemphylium botryosum Wallr.) is one of the major diseases of lentil (Lens culinaris Medik.) in South Asia and North America. The objective of the study was to identify linkage map position of the genes conferring resistance to stemphylium blight and the markers linked to the genes for its uti- lization in marker-assisted breeding. A popula- tion of 206 F 7 –derived recombinant inbred lines (RILs) was developed from a cross between ILL- 6002 (resistant) and ILL-5888 (susceptible). The RILs were planted in disease-screening plots at Ishurdi, Bangladesh in the 2006–2007 and 2008– 2009 winter cropping seasons. Signifcant varia- tion was detected among RILs for disease scores and frequency distributions suggested complex inheritance. An intraspecifc linkage map was constructed that comprised 139 markers; 21 sim- ple sequence repeats (SSR), 27 randomly ampli- fed polymorphic DNA (RAPD), 89 sequence related amplifed polymorphism (SRAP) markers and 2 morphological markers distributed over 14 linkage groups. One signifcant quantitative trait loci (QTL) was detected based on disease scores from the 2006–2007 experiment while three sig- nifcant QTLs were detected from the 2008–2009 experiment. The QTL QLG4 80–81 was common in both years and accounted for 25.2 and 46.0% of the variation of disease scores in 2006–2007 and 2008–2009 experiments, respectively. Two SRAP markers, ME5XR10 and ME4XR16c, and one RAPD marker, UBC34, located on linkage group 4, were signifcantly associated with the QLG4 80–81 in both crop years. After validation, the more tightly linked ME4XR16c marker may be used for marker assisted selection for stemphy- lium blight resistance. G.C. Saha, W. Chen, G.J. Vandemark, and F.J. Muehlbauer, Grain Legume Genetics and Physiology Research Unit, USDA-ARS, Wash- ington State University, Pullman, WA; A. Sarker, South Asia Regional Programs, International Center for Agricultural Research in the Dry Areas (ICARDA), New Delhi, India. Received 11 Dec. 2009. *Cor- responding author (gopesh_saha@wsu.edu). Abbreviations: ICIM, inclusive composite interval mapping; LG, linkage group; LOD, log of odds; QTL, quantitative trait loci; RAPD, randomly amplifed polymorphic DNA; RIL, recombinant inbred line; SRAP, sequence related amplifed polymorphism; SSR, simple sequence repeat. Published in Crop Sci. 50:1831–1839 (2010). doi: 10.2135/cropsci2009.12.0709 Published online 23 July 2010. © 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 September, 2010