Identification of quantitative trait loci for seedling cold tolerance using RILs derived from a cross between japonica and tropical japonica rice cultivars

Cold tolerance at the seedling stage of rice is an important phenotypic trait that causes normal plant growth and stable rice production in temperate regions as well as tropical high-lands in Asia and Africa. In order to find quantitative trait loci (QTLs)/genes associated with cold tolerance, we constructed a linkage map using 153 recombinant inbred lines (RILs) derived from a cross between a cold-tolerant temperate japonica cultivar, Geumobyeo, and a cold-sensitive tropical japonica breeding line, IR66160-121-4-4-2. The RILs were phenotyped for cold tolerance or sensitivity based on the degrees of cold tolerance as cold tolerance indices at the seedling stage. The seedlings for cold-tolerance/-sensitive traits were scored on the 7th day of the recovery period at 25°C after cold treatment at 10°C. Two QTLs (qCTS4a and qCTS4b) associated with cold tolerance at the seedling stage were identified on the long and short arms of chromosome 4 with an LOD score of 2.89 and 2.75, respectively, using composite interval mapping. The QTLs were flanked by simple sequence repeat (SSR) markers RM3648-RM2799 and RM3375a-RM558 that explained 8.3 and 7.8% of the total phenotypic variation, respectively. Seven of the selected RILs expressed cold tolerance at both the seedling and reproductive stages. The SSR markers associated with the QTLs will be useful for tracking favorable QTLs/genes into cold-sensitive elite cultivars and may have potential for pyramiding different QTLs for the improvement of cold tolerance in rice.     

Identification of new QTL for salt tolerance from rice variety Pokkali

Salt stress is an ever-present threat to rice production worldwide. Rice salinity tolerance is complex, both genetically and physiologically. The success and effectiveness in selecting salt-tolerant rice variety require the identification of QTL for the tolerance and closely linked molecular markers. In the present study, a RIL population consisting of 148 lines, derived from a cross between IR29 (salt-sensitive) and Pokkali (salt-tolerant), was used to identify new QTL for salt tolerance and investigate the relationships between salt stress caused injury and the changes in different physiological and morphological traits at the seedling stage. 14,470 high-quality SNP markers generated by the Rice 56K SNP array were converted to 1,467 bin markers for linkage mapping. A high-density genetic linkage map covering 1,680.9 cM was constructed, with the physical to genetic distance ratio being 222 Kb/cM. In total, 23 QTL for different salt tolerance indices were identified, including the previously reported Saltol which is currently used in breeding programmes. Three QTL for salt injury score (SIS) were located on chromosomes 1, 4 and 12, all being closely related to the long-distant Na⁺ transport from roots to shoots. These QTL showed additive effects, thus can be effectively used in breeding programme to pyramid various tolerance genes.     

Identification of salt tolerance‐improving quantitative trait loci alleles from a salt‐susceptible rice breeding line by introgression breeding

To improve salt tolerance of two elite rice varieties, Ce258 and Zhongguangxiang1 (ZGX1), two sets of introgression lines (ILs) each comprising 200 BC₁F₁₀ lines derived from a common donor, IR75862, and two recipient parents, Ce258 and ZGX1, were used for mapping of QTLs for four salt tolerance‐related traits at the seedling stage. Although the three parents were susceptible to salt, the two IL populations showed transgressive segregations for salt tolerance with 12 and 8 salt tolerance ILs in the Ce258‐ILs and ZGX1‐ILs. Eighteen main‐effect QTLs were identified for the four traits in the two IL populations, and the IR75862 alleles at most loci showed increased and decreased salt tolerance in the ZGX1 and Ce258 backgrounds, suggesting overwhelming genetic background effects on QTL detection for salt tolerance. The qDSS11 simultaneously detected in the two backgrounds was validated in a F₂ population derived from a salt tolerance line and ZGX1. Our results indicated that salt tolerance‐enhancing allele could be identified in the elite susceptible breeding lines and that introgression of the favourable alleles could facilitate the development of superior lines with greater salt tolerance levels.     

基于元分析的大豆生育期QTL的整合

共搜集整理了12年来已经报道的与大豆生育期有关的98个QTL,通过BioMercator2.1和公共标记映射整合到大豆公共遗传连锁图谱soymap2上,并利用元分析技术推断QTL位置,计算提取真正有效的QTL。发掘出大豆两个重要生育时期,共9个“真实QTL”及其连锁标记,其中与开花期(R1)相关的有7个,与成熟期(R8)相关的有2个,建立了QTL的一致性图谱,其中L连锁群上的一个定位区间包含一个已发表的有关R1的基因。在5个连锁群上共发现10个控制多个生育时期的QTL。本研究结果为大豆生育期QTL精细定位和基因克隆奠定了基础。     

小麦燕大1817×北农6号重组自交系群体在正常和盐胁迫水培条件下苗期性状的QTL定位

小麦苗期性状能够指示品种的耐盐性。本研究以小麦骨干亲本燕大1817与品系北农6号衍生的230个重组自交系为材料,利用2013年3个不同时间的水培试验数据和已经构建的SSR和SNP高密度遗传连锁图谱分别对正常和盐胁迫条件下根数和最长根长等7个苗期性状进行QTL定位。利用完备复合区间作图法(ICIM)共检测到69个加性效应QTL(LOD≥2.5),分布于除1A染色体外的所有20条染色体上,单个QTL解释的表型变异率为2.70%~19.00%。有46个QTL的增效效应来自于燕大1817,有23个QTL的增效效应来自于北农6号。有12个QTL能够在3个或3个以上的环境中被检测到,在燕大1817中定位到稳定的多分蘖主效QTL QTn.cau-7BS.1和盐胁迫条件下特异表达的根数QTL QRn.cau-2A,解析了小麦骨干亲本燕大1817的繁茂性和抗逆性遗传基础,为解析小麦品种耐盐遗传机制和耐盐性的分子标记辅助选择提供了重要信息。     

利用回交导入系群体发掘水稻种质资源中的有利耐盐QTL

以中等感盐籼稻IR64与粳稻Tarom molaii培育的85个BC₂F₈回交导入系为材料，定位苗期在140 mmol L^-1 NaCl胁迫下影响叶片盐害级别、幼苗存活天数、地上部和根部的K⁺、Na⁺浓度等6个耐盐相关性状的QTL。幼苗存活天数与地上部Na⁺浓度呈极显著负相关，与地上部K⁺浓度呈显著正相关，与根部K⁺、Na⁺浓度无关，表明叶片盐害是由于地上部Na⁺积累过多造成的。根部K⁺浓度与Na⁺浓度高度正相关，但与地上部的K⁺、Na⁺浓度均无关，表明根对K⁺、Na⁺的离子吸收与向地上部运输存在不同的机制。检测到影响6个耐盐相关性状的23个QTL，包括影响叶片盐害级别的5个、幼苗存活天数的6个、地上部K⁺浓度的4个、地上部Na+浓度的4个、根部K+浓度的1个和根部Na+浓度的3个。影响地上部K⁺、Na⁺浓度与影响根部K⁺、Na⁺浓度的QTL分布在不同基因组区域，进一步表明根和茎对K⁺、Na⁺的吸收存在不同的遗传机制。通过比较图谱，发现影响耐盐相关性状的23个QTL中有12个（占52.2%）与以往不同群体中影响耐盐相关性状的QTL定位在同一或相邻的染色体区域。其中在第2染色体RM240~RM112区间检测到1个影响地上部所有4个耐盐相关性状的主效QTL，其增加耐盐性的有利基因来自供体Tarom molaii，适宜用作标记辅助选择耐盐性的遗传改良。对从种质资源中发掘“隐蔽”耐盐QTL进行了讨论。     

Fine mapping of major QTLs for alkaline tolerance at the seedling stage in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) through genetic linkage analysis combined with high-throughput DNA sequencing

Exploiting genes and quantitative trait loci (QTLs) related to maize (Zea mays L.) alkaline tolerance is helpful for improving alkaline resistance. To explore the inheritance of maize alkaline tolerance at the seedling stage, a mapping population comprising 151 F_2:3 lines derived from the maize cross between Zheng58, tolerant to alkaline, and Chang7-2, sensitive to alkaline, was used to establish a genetic linkage map with 200 SSR loci across the 10 maize linkage groups, with an average interval of 6.5 cM between adjacent markers. QTLs for alkaline resistant traits of alkaline tolerance rating (ATR), germination rate (GR), relative conductivity (RC), weight per plant (WPP) and proline content (PC) were detected. The obtained results were as follows: Five QTLs on chromosomes 2, 5 and 6 (GR and WPP: chr. 2; PC and ATR: chr. 5; and RC: chr. 6) were mapped. For precise mapping of the QTLs related to alkaline resistance, two bulked deoxyribonucleic acid (DNA) pools were constructed using individual DNAs from the most tolerant 30 F₂ individuals and the most sensitive 30 F₂ individuals according to the ATR and used to establish a high density map of SLAF markers strongly associated with the ATR by specific locus amplified fragment sequencing (SLAF-Seq) combined with super bulked segregant analysis (superBSA). One marker-intensive region involved three SLAFs at 296,000–6,203,000 bp on chromosome 5 that were closely related to the ATR. Combined with preliminary QTL mapping with superBSA, two major QTLs on chromosome 5 associated with alkaline tolerance at the maize seedling stage were mapped to marker intervals of dCap-SLAF31521 and dCap-SLAF31535 and phi024 and dCap-SLAF31521, respectively. These QTL regions involved 9 and 75 annotated genes, respectively. These results will be helpful for improving maize alkaline tolerance at the seedling stage by marker-assisted selection programs and will be useful for fine mapping QTLs for maize breeding.     

一个水稻苗期耐冷性的主效QTL精细定位研究

苗期耐冷性是影响水稻生长发育的重要因素之一。此实验以低温导致叶片卷曲的卷曲度作为水稻苗期耐冷性指标,采用182个越光（粳型）/kasalath（籼型）//越光回交重组自交系（backcross recombinant inbred lines,BILs）和162个RFLP分子标记,对苗期耐冷性进行QTL（quantitative trait loci,QTL）定位分析。结果表明,BIL群体中苗期耐冷性均呈连续分布,属于数量性状遗传,并检测到4个控制苗期耐冷性的QTL,分布在第1、3、11、12染色体上,其贡献率为7.4%～21.9%,所有能增强耐冷性等位基因均来自越光;并在其目标区域内进一步设计分子引物把位于第12染色体上的主效qCTS-12定位在约77kb区域内。此研究结果及其检测到的QTLs两侧的连锁分子标记可为水稻苗期耐冷性分子育种以及相关基因克隆提供理论依据。     

Identification of QTLs for rice grain size and shape of Iranian cultivars using SSR markers

Grain size is a main component of rice appearance quality. In this study, we performed the SSR mapping of quantitative trait loci (QTLs) controlling grain size (grain length and breadth) and shape (length/breadth ratio) using an F₂ population of a cross between two Iranian cultivars, Domsephid and Gerdeh, comprising of 192 individuals. A linkage map with 88 markers was constructed, which covered 1367.9 cM of the rice genome with an average distance of 18 cM between markers. Interval mapping procedure was used to identify the QTLs controlling three grain traits, and QTLs detected were further confirmed using composite interval mapping. A total of 11 intervals carrying 18 QTLs for three traits were identifed, that included five QTLs for grain length, seven QTLs for grain breadth, and six QTLs for grain shape. A major QTL for grain length was detected on chromosome 3, that explained 19.3% of the phenotypic variation. Two major QTLs for grain breadth were mapped on chromosomes 3 and 8, which explained 34.1% and 20% of the phenotypic variation, respectively. Another two major QTLs were identified for grain shape on chromosomes 3 and 8, which accounted for 27.1% and 20.5% of the phenotypic variance, respectively. The two QTLs that were mapped for grain shape coincided with the major QTLs detected for grain length and grain breadth. Intrestingly, gs2 QTL specific to grain shape was detected on chromosome 2 that explained 15% of the phenotypic variation.     

Identification of quantitative trait loci for cold tolerance during the germination and seedling stages in rice (Oryza sativa L.)

Low temperature is a serious abiotic stress affecting rice production in subtropical and temperate areas. In this study, cold tolerance of rice at the germination and seedling stages were evaluated using one recombinant inbred line (RIL) population derived from a cross between Daguandao (japonica), with highly cold-tolerant at the seedling stage, and IR28 (indica), with more cold-tolerant at the germination stage, and the quantitative trait loci (QTL) mapping was conducted using the multiple interval mapping (MIM) approach. Continuous segregation in low temperature germinability (LTG) and cold tolerance at the seedling stage (CTS) were observed among the RIL populations. Most RILs were moderately susceptible or tolerant at the germination stage, but were susceptible at the seedling stage. No significant relationship was found in cold tolerance between the germination and seedling stages. A total of seven QTLs were identified with limit of detection (LOD) >3.0 on chromosomes 3, 8, 11 and 12, and the amount of variation (R ²) explained by each QTL ranged from 5.5 to 22.4%. The rice LTG might be regulated by two minor QTLs, with the CTS controlled by one major QTL [qCTS8.1 (LOD = 16.1, R ² = 22.4%)] and several minor loci. Among these loci, one simultaneously controls LTG (qLTG11.1) and CTS (qCTS11.1). Several cold-tolerance-related QTLs identified in previous studies were found to be near the QTLs detected here, and three QTLs are novel alleles. The alleles from Daguandao at six QTLs increased cold tolerance and could be good sources of genes for cold tolerance. In addition, only one digenic interaction was detected for CTS, with a R ² value of 6.4%. Those major or minor QTLs could be used to significantly improve cold tolerance by marker-assisted selection (MAS) in rice.     

Quantitative trait loci for stay-greenness and agronomic traits provide new insights into chlorophyll homeostasis and nitrogen use in rice

Functional stay-green (FSG) is characterized by delayed senescence during the reproductive stage in rice. A recombinant inbred line (RIL) population derived from ‘Pusa 677’/‘PSG16’ was used to study the genetics of FSG in a rice mutant, ‘PSG16’. The RILs exhibited significant variation under two N regimes for agro-morphological traits, leaf chlorophyll content, flowering time, yield components and nitrogen (N) use. Using a genome wide linkage map spanning 1910.8 cM with 104 polymorphic markers, we have mapped six major quantitative trait loci (QTLs). One robust QTL on chromosome 1 was associated consistently across different N regimes with chlorophyll content and flowering time. The QTL on chromosome 7 was associated with grain number, whereas the QTL on chromosome 6 was found related to N harvest index and spikelet fertility. Although ‘PSG16’ showed a clear advantage in grain yield as well as having better N assimilation, we could not establish a direct genetic relationship SG trait and N use. Based on the QTL information, FSG trait of ‘PSG16’ could be useful in deciphering multiple stress responses in rice.     

利用重组自交群体检测水稻抗亚铁毒胁迫的QTLs

潜育性水稻田广泛分布于中国、斯里兰卡、印度、印度尼西亚、塞拉里昂、利比亚、尼日利亚、哥伦比亚和菲律宾等国，其中我国南方稻区就有670万公顷低产潜育性水稻田。该类水稻田还原性强，矿质营养失调，尤以Fe2+ 过量积累，对水稻生长发育产生不良的逆境胁迫作用。培育抗亚铁毒的水稻品种是简便、经济有效地提高稻谷产量的重     

Mapping quantitative trait loci for salt tolerance at germination and the seedling stage in barley (Hordeum vulgare L.)

Quantitative trait loci (QTLs) controlling salt tolerance at germination and the seedling stage in barley (Hordeum vulgare L.) were identified by interval mapping analysis using marker information from two doubled haploid (DH) populations derived from the crosses, Steptoe/Morex and Harrington/TR306. Interval mapping analysis revealed that the QTLs for salt tolerance at germination in the DH lines of Steptoe/Morex were located on chromosomes 4 (4H), 6(6H), and 7(5H), and in the DH lines of Harrington/TR306 on chromosomes 5(1H) and 7(5H). In both DH populations, the most effective QTLs were found at different loci on chromosome 7(5H). Genetic linkage between salt tolerance at germination and abscisic acid (ABA) response was found from QTL mapping. The QTLs for the most effective ABA response at germination were located very close to those for salt tolerance on chromosome 7 (5H) in both crosses. The QTLs for salt tolerance at the seedling stage were located on chromosomes 2(2H), 5(1H), 6(6H), and 7(5H) in the DH lines of Steptoe/Morex, and on chromosome 7(5H) in the DH lines of Harrington/TR 306. Their positions were different from those of QTLs controlling salt tolerance at germination, indicating that salt tolerance at germination and at the seedling stage were controlled by different loci. This revised version was published online in July 2006 with corrections to the Cover Date.     

Quantitative trait loci controlling rice seed germination under salt stress

Salt tolerance of rice (Oryza sativa L.) at the seed germination stage is one of the major determinants for the stable stand establishment in salinity soil. One population of recombinant inbred lines (RILs, F_2:9), derived from a cross between a japonica rice landrace tolerant to salt stress and a sensitive indica rice variety, was used to determine the germination traits including imbibition rate and germination percentage under control (water) and salt stress (100 mM NaCl) for 10 days at 30 °C. The multiple interval mapping (MIM) were applied to conduct QTL for the traits. The results showed that seed germination was a quantitative trait controlled by several genes, and strongly affected by salt stress. A total of 16 QTLs were detected in this study, and each QTL could explain 4.6–43.7% of the total phenotypic variance. The expression of these QTLs might be developmentally regulated and growth stage-specific. In addition, only one digenic interaction was detected under salt stress, showing small effect on germination percentage with R² 2.7%. Among sixteen QTLs detected in this study, four were major QTLs with R² > 30%, and some novel alleles of salt tolerance genes in rice. The results demonstrated that the japonica rice Jiucaiqing is a good source of gene(s) for salt tolerance and the major or minor QTLs identified could be used to improve the salt tolerance by marker-assisted selection (MAS) in rice.     

Identification of drought responsive QTLs during vegetative growth stage of rice using a saturated GBS-based SNP linkage map

Drought is a major abiotic constraint for rice production worldwide. The quantitative trait loci (QTLs) for drought tolerance traits identified in earlier studies have large confidence intervals due to low density linkage maps. Further, these studies largely focused on the above ground traits. Therefore, this study aims to identify QTLs for root and shoot traits at the vegetative growth stage using a genotyping by sequencing (GBS) based saturated SNP linkage map. A recombinant inbred line (RIL) population from a cross between Cocodrie and N-22 was evaluated for eight morphological traits under drought stress. Drought was imposed to plants grown in 75 cm long plastic pots at the vegetative growth stage. Using a saturated SNP linkage map, 14 additive QTLs were identified for root length, shoot length, fresh root mass, fresh shoot mass, number of tillers, dry root mass, dry shoot mass, and root-shoot ratio. Majority of the drought responsive QTLs were located on chromosome 1. The expression of QTLs varied under stress and irrigated condition. Shoot length QTLs qSL1.38 and qSL1.11 were congruent to dry shoot mass QTL qDSM1.38 and dry root mass QTL qDRM1.11, respectively. Analysis of genes present within QTL confidence intervals revealed many potential candidate genes such as laccase, Calvin cycle protein, serine threonine protein kinase, heat shock protein, and WRKY protein. Another important gene, Brevis radix, present in the root length QTL region, was known to modulate root growth through cell proliferation and elongation. The candidate genes and the QTL information will be helpful for marker-assisted pyramiding to improve drought tolerance in rice.     

QTL mapping for seedling traits associated with low‐nitrogen tolerance using a set of advanced backcross introgression lines of rice

Nitrogen (N) deficiency is a major yield‐limiting factor in rice production. The objective of this study was to identify putative QTLs for low‐N stress tolerance of rice, using an advanced backcross population derived from crosses between an indica cultivar ‘93‐11’ and a japonica cultivar ‘Nipponbare’ and genotyped at 250 marker loci. Plant height, maximum root length, root dry weight, shoot dry weight and plant dry weight under two N conditions and their relative traits were used to evaluate low‐N tolerance at the seedling stage. A total of 44 QTLs were identified on chromosomes 1, 2, 3, 4, 5, 6, 8 and 9. Eight intervals on five chromosomes were identified to harbour multiple QTLs, suggesting pleiotropism or multigenic effects according to the contributor of alleles. Some QTL clusters were found in the nearby regions of genes associated with N recycling in rice, indicating that the key N metabolism genes might have effects on the expression of QTLs. Several unique QTLs for relative traits were detected, which suggested the specific genetic basis of relative performance.     

Detection of QTLs for salt tolerance in Asian barley (Hordeum vulgare L.) by association analysis with SNP markers

Two hundred ninety-six Asian barley (Hordeum vulgare L.) accessions were assessed to detect QTLs underlying salt tolerance by association analysis using a 384 single nucleotide polymorphism (SNP) marker system. The experiment was laid out at the seedling stage in a hydroponic solution under control and 250 mM NaCl solution with three replications of four plants each. Salt tolerance was assessed by leaf injury score (LIS) and salt tolerance indices (STIs) of the number of leaves (NL), shoot length (SL), root length (RL), shoot dry weight (SDW) and root dry weight (RDW). LIS was scored from 1 to 5 according to the severity of necrosis and chlorosis observed on leaves. There was a wide variation in salt tolerance among Asian barley accessions. LIS and STI (SDW) were the most suitable traits for screening salt tolerance. Association was estimated between markers and traits to detect QTLs for LIS and STI (SDW). Seven significant QTLs were located on chromosomes 1H (2 QTLs), 2H (2 QTLs), 3H (1 QTL), 4H (1 QTL) and 5H (1 QTL). Five QTLs were associated with LIS and 2 QTLs with STI (SDW). Two QTLs associated with LIS were newly identified on chromosomes 3H and 4H.     

QTL analysis of cooked rice grain elongation, volume expansion, and water absorption using a recombinant inbred population

The traits of elongation, volume expansion, and water absorption are very important in determining the quality of cooked rice grains. In this study, quantitative trait loci (QTL) analysis of these traits was performed using a recombinant inbred population derived from a cross between two indica cultivars, ‘Zhenshan 97’ and ‘Minghui 63 ,’ which are the parents of the most widely grown hybrid rice in China. Using a linkage map based on 221 molecular marker loci covering a total of 1796 cM, a total of 33 QTLs were identified for the nine traits tested. QTLs were detected on chromosomes 1– 3 , 5– 9 , and 11 , respectively. The QTLs identified included three for cooked rice grain length elongation (chromosomes 2 , 6 , and 11), six for width expansion (chromosomes 1‐ 3 , 6 , 9 , and 11) and two for water absorption (chromosomes 2 and 6). Interestingly, a single QTL located near the wx gene on chromosome 6 seemed to influence all the traits tested for the cooked rice quality.     

玉米光周期敏感相关性状发育动态QTL定位

玉米是短日照作物,大多数热带种质对光周期非常敏感。光周期敏感性限制了温、热地区间的种质交流。研究玉米光周期敏感性的分子机理,有利于玉米种质的扩增、改良、创新,提高玉米品种对不同光周期变化的适应性。本研究以对光周期钝感的温带自交系黄早四和对光周期敏感的热带自交系CML288为亲本配置的组合衍生的一套207个重组自交系为材料,在长日照环境条件下对不同发育时期的叶片数、株(苗)高变化进行QTL分析。结果表明,双亲间的最终可见叶片数和株高差异很大;发育初期CML288的叶片数和苗高都低于黄早四,而发育后期CML288的叶片数和株高都明显高于黄早四;测定各时期F₇重组自交系间也存在显著差异。利用包含237个SSR标记、图谱总长度1 753.6 cM、平均图距7.40 cM的遗传连锁图谱,采用复合区间作图法,分别检测到控制叶片数和株(苗)高发育的QTL 11个和20个。但是,没有一个条件QTL 能在测定的几个时期都有效应。在长日照条件下,控制叶片数与株(苗)高的非条件与条件QTL主要集中在第1、9和10染色体上,特别是在第10染色体的标记umc1873附近均检测到了影响这两个性状的QTL,且在不同的发育时期单个条件和非条件QTL所解释的表型变异分别为4.34%~25.74%和10.02%~22.57%,表明这一区域可能包含光周期敏感性关键基因。     

Construction of a genetic linkage map and QTL analysis of fiber-related traits in upland cotton (Gossypium hirsutum L.)

A genetic linkage map with 70 loci (55 SSR, 12 AFLP and 3 morphological loci) was constructed using 117 F₂ plants obtained from a cross between two upland cotton cultivars Yumian 1 and T586, which have relatively high levels of DNA marker polymorphism and differ remarkably in fiber-related traits. The linkage map comprised of 20 linkage groups, covering 525 cM with an average distance of 7.5 cM between two markers, or approximately 11.8% of the recombination length of the cotton genome. The present genetic linkage map was used to identify and map the quantitative trait loci (QTLs) affecting lint percentage and fiber quality traits in 117 F_2:3 family lines. Sixteen QTLs for lint percentage and fiber quality traits were identified in six linkage groups by multiple interval mapping: four QTLs for lint percentage, two QTLs for fiber 2.5% span length, three QTLs for fiber length uniformity, three QTLs for fiber strength, two QTLs for fiber elongation and two QTLs for micronaire reading. The QTL controlling fiber-related traits were mainly additive, and meanwhile including dominant and overdominant. Several QTLs affecting different fiber-related traits were detected within the same chromosome region, suggesting that genes controlling fiber traits may be linked or the result of pleiotropy.