CROP SCIENCE, VOL. 52, JULY– AUGUST 2012 1583 RESEARCH A biotic stresses are becoming the major limiting factors for crop production especially under globally changing climatic conditions. Among them, drought and salinity are considered as the two of the major abiotic stresses (Brown and Halwei, 1998; Pandey et al., 2000). Drought is a serious problem in rainfed rice area, which occupies 50% of total rice acreage in the world. In Identiication of Genetic Overlaps for Salt and Drought Tolerance Using Simple Sequence Repeat Markers on an Advanced Backcross Population in Rice Yun Wang, Jinping Zang, Yong Sun, Jauhar Ali, Jianlong Xu,* and Zhikang Li ABSTRACT Salinity and drought are two of the major abiotic stresses that affect rice (Oryza sativa L.) production especially in Asia. Quantitative trait loci (QTL) for salt tolerance (ST) at seedling stage and drought tolerance (DT) at reproductive stage were identiied using 77 BC 2 F 8 advanced backcross introgression lines (ILs) derived from a cross of Teqing × Binam in Teqing background. Ten ST QTL were identiied governing days to seedlings survival (DSS), score on salt toxicity symptoms on leaves (SST), shoot K + concentration (SKC), and shoot Na + concentration (SNC) at seedling stage, and 23 QTL were identiied under reproductive stage drought and irrigated conditions for panicle number per plant (PN), thousand grain weight (TGW), seed fertility (SF), plant height (PH), and grain yield per plant (GYP). Most QTL detected at reproductive stage showed obvious differential expression to drought stress. In addition, another eight QTL were detected by trait ratio of the stress to the irrigation; the alleles at all loci except QSf3 showed increasing trait values to be associated with Binam, indicating Binam alleles at these loci could improve DT under drought stress. Upon comparison of identiied ST and DT QTL we found 14 QTL shared the same genome regions with similar gene actions, clearly suggesting that genetic overlap existed between the two abiotic stress tolerances. Pyramiding of favorable alleles from Binam into Teqing background should allow us to develop superior ILs with higher levels of ST and DT. Y. Wang, Shenyang Agricultural Univ. /Key Lab. for Northern Japonica Rice Genetics and Breeding of Ministry of Education, Shenyang 110866, China; Y. Wang, J. Zang, Y. Sun, J. Xu, and Z. Li, Institute of Crop Sciences/National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Beijing 100081, China; J. Ali and Z. Li, International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines. Yun Wang and Jinping Zang equally contributed to this work. Received 1 Dec. 2011. *Corresponding author (xujlcaas@ yahoo.com.cn or xujl@caas.net.cn). Abbreviations: DSS, days to seedling survival; DT, drought tolerance; GYP, grain yield per plant; IL, introgression line; MAS, marker-assisted selection; PH, plant height; PN, panicle number per plant; QTL, quantitative trait loci/locus; RGYP, ratio of grain yield per plant under drought stress to control condition; RPN, ratio of panicle number per plant under drought stress to control condition; RSF, ratio of seed fertility under drought stress to control condition; RTGW, ratio of thousand grain weight under drought stress to control condition; SF, seed fertility; SGYP, grain yield per plant under drought stress condition; SKC, shoot K + concentration; SNC, shoot Na + concentration; SSF, seed fertility under drought stress condition; SSR, simple sequence repeat; SST, score on salt toxicity symptoms on leaves; ST, salt tolerance; STGW, thousand grain weight under drought stress condition; TGW, thousand grain weight. Published in Crop Sci. 52:1583–1592 (2012). doi: 10.2135/cropsci2011.12.0628 © 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.