Construction of a high-density SSR genetic linkage map and identification of QTL for storage-root yield and dry-matter content in sweetpotato

Sweetpotato(Ipomoea batatas(L.)Lam.)is a widely grown food crop especially in developing countries.Increasing storage-root yield and dry-matter content has been the main breeding objective of the crop,and DNA marker-assisted breeding is needed for this purpose.In this study,using a mapping population of 500 F1 individuals from a cross between Xushu 18(female)and Xu 781(male),we constructed a highdensity genetic linkage map of sweetpotato using 601 simple-sequence repeat(SSR)primer pairs.The Xushu 18 map contained 90 linkage groups with 5547 SSR markers and spanned 18,263.5 cM,and the Xu 781 map contained 90 linkage groups with 4599 SSR markers and spanned 18,043.7 cM,representing the highest genome coverage yet reported for sweetpotato.We identified 33 QTL for storage-root yield and 16 QTL for dry-matter content,explaining respectively 6.5%–47.5%and 3.2%–18.9%of variation.These results provide a foundation for fine-mapping and cloning of QTL and for marker-assisted breeding in sweetpotato.

Genetic linkage mapping and QTL identification for salinity tolerance in Indian mustard(Brassica juncea L.Czern and Coss.)using SSR markers

Soil salinity is one of the major environmental constraints that limits crop yield and nearly 7%of the total area worldwide is affected by salinity.Salinity-induced oxidative stress causes membrane damage during germination and seedling growth.Indian mustard is a major oilseed crop in India and its production and productivity are severely affected by salt stress.Breeding Brassica cultivars for salinity tolerance by conventional means is very difficult and time-consuming.Therefore,understanding the molecular components associated with salt tolerance is needed to facilitate breeding for salt tolerance in Brassica.In this investigation,quantitative trait loci(QTLs)associated with salt tolerance were identified using F_(2:3)mapping population developed from a cross between CS52(salinity tolerant)and RH30(salinity sensitive).Parents and F_(2:3)were evaluated under controlled and salinity stress conditions for 14 morpho-physiological traits for two consecutive generations(F2 and F_(2:3)),explaining proportion of the phenotypic variance under control condition.Simple sequence repeat(SSR)markers were used for mapping studies.A genetic linkage map based on 42 simple sequence repeats(SSRs)markers was constructed covering 2298.5 cM(Haldane)to identify the loci associated with salt tolerance in Brassica juncea.Forty-one SSRs showing polymorphism in the parents(CS52 and RH30)were mapped on 8 linkage groups(C1–C8).One marker(nga 129)did not map to any of the linkage group and was excluded from mapping.Linkage group 5(C5;317.9 cM)was longest and linkage group 1(C1,255.0 cM)was shortest.Further,we identified 15 QTLs controlling 8 traits using F_(2:3)population.These QTLs explained 12.44–60.63%of the phenotypic variation with a LOD score range of 3.62–5.97.Out of these QTLs,QMI4.1 related to membrane injury showed 51.28%phenotypic variance with a LOD score of 3.34.QTL QBYP8.1 related to biological yield per plant showed 60.63%phenotypic variance at a LOD score of 3.62.The highest LOD score of 5.97 was recorded for QTL related to seed yield per plant(QSYP4.1).Major QTLs were QTL for biological yield per plant(QBYP8.1),QTL for siliquae per plant(QSP4.1),QTL for primary branches(QPB4.1),QTLs for seed per siliqua(QSS4.1,QSS4.2),QTL for seed yield per plant(QSYP4.1),and QTL for membrane injury(QMI8.1)which showed more than 50%phenotypic variance.These QTLs identified in our study need to be confirmed in other populations as well so that these can be used in marker-assisted selection and breeding to enhance salt tolerance in Brassica juncea.

Rapid Constructing a Genetic Linkage Map by AFLP Technique and Mapping a New Gene tms5

In this study, we reported the repaid construction of a molecular marker linkage map of rice (Oryza sativa L.). An F-2 population from the cross between Annong S-1 and Nanjing 11 was used to construct a genetic linkage map of rice. Total of 142 newly screened AFLP markers and 30 anchor markers (25 SSR markers and 5 RFLP markers) were mapped on the 12 chromosomes covering 1537.4 cM of rice genome. The average interval between these markers was 9.0 cM. The total work which usually was finished in more than one year was finished within only 3 months by one person. This is the first plant AFLP map developed in China. A new thermosensitive genic male sterile gene in rice, tms5, was Egged and mapped onto chromosome 2 during the development of the linkage map.

Genetic Analysis and Linkage Mapping in a Resource Pig Population Using Microsatellite Markers

The use of markers and linkage map construction are important for QTL mapping in pigs. In this article, the genetic characteristics were studied and the linkage map was constructed in a pig resource population including 214 individuals by typing 39 microsatellite marker loci on Sus scrofa chromosomes, SSC4, SSC6, SSC7, SSC8, and SSC13. Results indicated that the average allele number, the average observed beterozygosity （Ho）, and the average polymorphism information content （PIC） in F1 and F2 population were 3.2, 0.528, 0.463 and 3.2, 0.496, 0.447, respectively. In the pig resource population, the average informative meiosis （IM） was 217.4 （44-316）, and the average linkage map length between the two sexes on the five chromosomes were 172.3 cM （SSC4）, 168.7 cM （SSC6）, 191.7 cM （SSC7）, 197.3 cM （SSC8）, and 178.3 cM （SSC13）. The orders of microsatellite marker loci in the linkage maps were identical to, but the length was greater than, those of USDA-MARC reference map. The results of this research showed the genetic relationship and genetic characteristics of the microsatellite markers in the pig resource family population, and the linkage map could be used to for QTL mapping in the subsequent study.

Construction of Molecular Genetic Linkage Map Based on an RIL Population of Rice and Detection of QTLs for Tiller Angle

In this study, an RIL （recombinant inbred line） population containing 240 lines was developed by single seed descent method （SSD） based on a parent com- bination of small-grain indica cultivar Kasalath and large-grain japanica cultivar TD70 with significant differences in plant type traits, to construct the molecular genetic linkage map. Totally 838 SSR （Simple Sequence Repeat） markers were used for polymorphism screening between parents, 302 SSR markers with polymorphism were detected, with a frequency of 36.04%; 141 SSR markers with clear amplified bands and uniform distribution in the genome were finally used for genotype analysis of the RIL population. According to the experimental results, the frequency of male and female genotype in this RIL population was respectively 53% and 47%, suggesting good balance in population structure. A molecular genetic linkage map of rice was constructed by 141 markers based on a RIL population of 240 lines, with a total genetic distance of about 1 832.47 cM covering all 12 chromosomes, an average genetic distance between markers of 12.70 cM and a range of genetic distance be- tween markers of 0.43-36.11 cM, which is consistent with basic requirements of quantitative trait locus （QTL） mapping. Except for few markers on chromosomes 1 and 8, the order and location of markers is similar to the published sequences of Nipponbare. QTL analysis for the tiller angle was conducted with this RIL population of 240 lines, and results showed that three QTLs controlling tiller angle were detected on chromosome 8, 9 and 11, which were named qTA8, qTA9 and qTA11, with a contribution rate of 4.10%, 26.08% and 4.35%, respectively. To be specific, qTA9 contained Tiller Angle Controlling （TAC1） gene. The construction of this molecular genetic linkage map laid the foundation for genetic analysis and QTL mapping of various traits in the progeny of indica and japonica.

A Preliminary Genetic Linkage Map of Sinonovacula constricta(Lamarck, 1818) Based on Microsatellites Derived from RAD Sequencing

Sinonovacula constricta is one of the important economic aquaculture species in China. In this study, we constructed genetic linkage maps of S. constricta based on 300 microsatellite markers derived from RAD-seq using an F1 full-sib family. The female map contained 204 microsatellites assigned to 22 linkage groups, which covered 1529.5 cM with an average interval of 10.3 cM. The male consisted of 187 microsatellites in 19 linkage groups corresponding to the haploid chromosome number(n(28)19), which spanned 1429.3 cM with an average interval of 8.7 cM. The genome coverage was approximately 83.5% and 81.4%, respectively. An integrated map was constructed according to the common markers in parental linkage groups, which had a total length of 1683.8 cM with an average interval of 7.3 cM. The genome coverage of the integrated map was approximately 86.3%. The genetic linkage map would form the foundation for further studies on the quantitative trait loci(QTL), as well as accelerating the breeding process of this species.

Construction of Genetic Linkage Map Based on SSR Markers in Peanut(Arachis hypogaea L.)

Molecular genetic maps of crop species can be used in a variety of ways in breeding and genomic research such as identification and mapping of genes and quantitative trait loci （QTLs） for morphological, physiological and economic traits of crop species. However, a comprehensive genetic linkage map for cultivated peanut has not yet been developed due to the extremely low frequency of DNA polymorphism in cultivated peanut. In this study, 142 recombinant inbred lines （RILs） derived from a cross between Yueyou 13 and Zhenzhuhei were used as mapping population in peanut （Arachis hypogaea L.）. A total 652 pairs of genomic-SSR primer and 392 pairs of EST-SSR primer were used to detect the polymorphisms between the two parents. 141 SSR primer pairs, 127 genomic-SSR and 14 EST-SSR ones, which can be used to detect polymorphisms between the two parents, were selected to analyze the RILs population. Thus, a linkage genetic map which consists of 131 SSR loci in 20 linkage groups, with a coverage of 679 cM and an average of 6.12 cM of inter-maker distance was constructed. The putative functions of 12 EST-SSR markers located on the map were analyzed. Eleven showed homology to gene sequences deposited in GenBank. This is the first report of construction of a comprehensive genetic map with SSR markers in peanut （Arachis hypogaea L.）. The map presented here will provide a genetic framework for mapping the qualitative and quantitative trait in peanut.

SSR genetic linkage map construction of pea(Pisum sativum L.) based on Chinese native varieties

Simple sequence repeat(SSR)markers have previously been applied to linkage mapping of the pea(Pisum sativum L.)genome.However,the transferability of existing loci to the molecularly distinct Chinese winter pea gene pool was limited.A novel set of pea SSR markers was accordingly developed.Together with existing SSR sequences,the genome of the G0003973(winter hardy)×G0005527(cold sensitive)cross was mapped using 190 F2individuals.In total,157 SSR markers were placed in 11 linkage groups with an average interval of 9.7 cM and total coverage of 1518 cM.The novel markers and genetic linkage map will be useful for marker-assisted pea breeding.

A SSR Linkage Map of Maizex Teosinte F_2 Population and Analysis of Segregation Distortion

In this study,a linkage genetic map was constructed using a F2 population derived from a cross between a elite maize inbred,B73,and its progenitor,Teosinte（Z.mays ssp.mexicana）,through 205 simple sequence repeat（SSR） markers and one morphological marker.By Mapmaker 3.0,polymorphic markers were clustered into 10 groups,covering 10 chromosomes of maizexteosinte,with a total length of 2 002.4 cM and an average interval of 9.7 cM.Genotyping errors were detected using R/QTL（LOD=2.0） in 109 markers referring to 176 individuals,distributed across all 10 chromosomes with a ratio 1.2%.Projected error loci were re-run and 304 out of the 460 were confirmed as errors and replaced.A new linkage map was constructed,in which markers maintained the same order but the total map length decreased to 1 947.8 cM,with an average interval of 9.4 cM between markers.In total,25.2%（P0.05） markers were identified to have segregation distortion,in which 34.6% deviated towards the pollination parent（B73）,30.8% deviated towards Teosinte,32.7% deviated towards heterozygote and 1.9% deviated towards both parents.This map was also compared with published maizexteosinte and maize IBM map.

A genetic linkage map with 178 SSR and 1901 SNP markers constructed using a RIL population in wheat (Triticum aestivum L.)

The construction of high density genetic linkage map provides a powerful tool to detect and map quantitative trait loci(QTLs) controlling agronomically important traits. In this study, simple sequence repeat(SSR) markers and Illumina 9K i Select single nucleotide polymorphism(SNP) genechip were employed to construct one genetic linkage map of common wheat(Triticum aestivum L.) using 191 recombinant inbred lines(RILs) derived from cross Yu 8679×Jing 411. This map included 1 901 SNP loci and 178 SSR loci, covering 1 659.9 c M and 1 000 marker bins, with an average interval distance of 1.66 c M. A, B and D genomes covered 719.1, 703.5 and 237.3 c M, with an average interval distance of 1.66, 1.45 and 2.9 c M, respectively. Notably, the genetic linkage map covered 20 chromosomes, with the exception of chromosome 5D. Bioinformatics analysis revealed that 1 754(92.27%) of 1 901 mapped SNP loci could be aligned to 1 215 distinct wheat unigenes, among which 1 184(97.4%) were located on o ne single chromosome, and the rest 31(2.6%) were located on 2 to 3 chromosomes. By performing in silico comparison, 214 chromosome deletion bin-mapped expressed sequence tags(ESTs), 1 043 Brachypodium genes and 1 033 rice genes were further added onto the genetic linkage map. This map not only integrated genetic and physical maps, SSR and SNP loci, respectively, but also provided the information of Brachypodium and rice genes corresponding to 1 754 SNP loci. Therefore, it will be a useful tool for comparative genomics analysis, fine mapping of QTL/gene controlling agronomically important traits and marker-assisted selection breeding in wheat.

High-density SNP genetic linkage map construction and quantitative trait locus mapping for resistance to cucumber mosaic virus in tobacco(Nicotiana tabacum L.)

Genetic linkage maps are essential for studies of genetics, genomic structure, and genomic evolution, and for mapping quantitative trait loci (QTL). Identification of molecular markers and construction of genetic linkage maps in tobacco (Nicotiana tabacum L.), a classical model plant and important economic crop, have remained limited. In the present study we identified a large number of single nucleotide polymorphism (SNP) markers and constructed a high-density SNP genetic map for tobacco using restriction site-associated DNA sequencing. In 1216.30 Gb of clean sequence obtained using the Illumina HiSeq 2000 sequencing platform, 99,647,735 SNPs were identified that differed between 203 sequenced plant genomes and the tobacco reference genome. Finally, 13,273 SNP markers were mapped on 24 high-density tobacco genetic linkage groups. The entire linkage map spanned 3421.80 cM, with a mean distance of 0.26 cM between adjacent markers. Compared with genetic linkage maps published previously, this version represents a considerable improvement in the number and density of markers. Seven QTL for resistance to cucumber mosaic virus (CMV) in tobacco were mapped to groups 5 and 8. This high-density genetic map is a promising tool for elucidation of the genetic bases of QTL and for molecular breeding in tobacco.

SNP-based linkage mapping for validation of adult plant stripe rust resistance QTL in common wheat cultivar Chakwal 86

Wheat crops in China are constantly challenged by stripe rust. Deployment of cultivars with diverse resistances is the best strategy to control the disease. A recombinant inbred line(RIL) population derived from a cross between the resistant cultivar Chakwal 86 and susceptible landrace Mingxian 169 was studied in multiple environments to examine the underlying genetics and to identify quantitative trait loci(QTL) for stripe rust resistance.One hundred and twenty-eight RILs were genotyped with wheat 35 K SNP array and a genome-wide linkage map with 1480 polymorphic SNP markers, or bins, was constructed.Two major QTL on chromosomes 1BL and 3BS, and one minor QTL on 6BS had significant effects in reducing stripe rust severity. The QTL were validated using composite interval mapping(CIM) and inclusive composite interval mapping(ICIM). These methods explained59.0%–74.1% of the phenotype variation in disease response. The QTL on chromosome 1 BL was confirmed to be Yr29/Lr46 and the one on 3BS was the resistance allele identified in CIMMYT germplasm but was not Yr30/Sr2. The QTL on 6BS probably corresponded to previously known QTL. RILs with combined QTL were more resistant than those with single or no QTL. Kompetitive allele-specific PCR(KASP) assays for the QTL with largest effect QTL on chromosome 3BS were performed on a subset of RILs and 150 unrelated wheat lines. The QTL on 3BS with its linked KASP markers can be used in marker-assisted selection to improve stripe rust resistance in breeding programs.

Identification of powdery mildew resistance loci in wheat by integrating genome-wide association study(GWAS) and linkage mapping

Wheat powdery mildew(Blumeria graminis f.sp.tritici, Bgt) is a disease of increasing importance globally due to the adoption of high yielding varieties and modern sustainable farming technologies.Growing resistant cultivars is a preferred approach to managing this disease, and novel powdery mildew resistance genes are urgently needed for new cultivar development.A genome-wide association study was performed on a panel of 1292 wheat landraces and historical cultivars using 5011 single nucleotide polymorphism(SNP)markers.The association panel was evaluated for reactions to three Bgt inoculants, OKS(14)-B-3-1, OKS(14)-C-2-1, and Bgt15.Linkage disequilibrum(LD) analysis indicated that genome-wide LD decayed to 0.1 at 23 Mb, and population structure analysis revealed seven subgroups in the panel.Association analysis using a mixed linear model(MLM) identified three loci for powdery mildew resistance on chromosome 2 B, designated QPm.stars-2BL1,QPm.stars-2BL2, and QPm.stars-2BL3.To evaluate the efficacy of GWAS in gene discovery,QPm.stars-2BL2 was validated using F2 and F2:3 populations derived from PI420646 × OK1059060-126135-3.Linkage analysis delimited the powdery mildew resistance gene in PI 420646 to an interval where QPm.stars-2BL2 was located, lending credence to the GWAS results.QPm.stars-2BL1 and QPm.stars-2BL3, which were associated with four SNPs located at 457.7–461.7 Mb and two SNPs located at 696.6–715.9 Mb in the Chinese Spring reference IWGSC RefSeq v1.0, respectively, are likely novel loci for powdery mildew resistance and can be used in wheat breeding to improve powdery mildew resistance.

A Genetic Linkage Map of Brassica campestris L.ssp. pekinensis (syn. B. rapa L. ssp. pekinensis)

A molecular genetic map of Chinese cabbage was constructed with a 102 recombinant inbred (RI) population from a cross of two cultivated Chinese cabbage lines 177 and 276, using AFLP and RAPD markers. 352 markers including 265 AFLP markers and 87 RAPD markers were integrated into 17 linkage groups. It covered a total of 2 665. 7 cM with an average interval of 7. 6 cM. AFLP marker is efficient for map construction while it easily forms clusters to cause big gaps in map. A total of 13.92 % abnormal segregation markers distributed in the map. The molecular genetic map is fundamental for gene localization, comparative genomics, and QTL mapping of important agronomic traits.

Linkage map and QTL mapping of red flesh locus in apple using a R1R1×R6R6 population

The red flesh in apple fruit is a desired trait by consumers and it is associated to the anthocyanin content,which is mainly controlled by MdMYB10 with a R6 promoter.In this study,a high-density linkage group was constructed using the‘Fuji’x‘Red3’population which contained homozygous alleles R1R1 and R6R6,respectively.The linkage group consists of 7630 SNPs along 17 linkage groups,spanning 2270.21 cM,with an average density of 0.30 cM permarker.The cyanidin-3-galactoside concentration was used as the phenotypic data in QTL analysis.Moreover,one QTL peak which was flaked by two markers,marker2187260 to marker2173766,with LOD scores of 4.49 was detected.This QTL ranged from 0 to 40.79 cM on the top of linkage group(LG16).In addition one candidate molecular marker(marker2175442)in this QTL was identified,which was significant correlated with the flesh cyanidin-3-galactoside concentration.These genetic findings enrich the breeding basis of fruit flesh coloration in apple.

Development of a high-density SSR genetic linkage map in sweet potato

Simple sequence repeat(SSR) markers have been proved to be a very powerful tool for quantitative trait locus(QTL) mapping, marker-assisted selection and comparative genomics research in many crop species. However, a high-density SSR genetic linkage map is still lacking because there are only a few SSR markers available in sweet potato. In this study, a total of 2545 simple sequence repeat(SSR) primer pairs, including 1215 genomic SSR(gSSR) primer pairs and 1330 BES-SSR(bSSR) primer pairs designed from the genome sequence and BAC-end sequence of sweet potato, respectively, were screened with sweet potato cultivars Luoxushu 8 and Zhengshu 20 and their randomly sampled two F1 individuals and 571 of them generated polymorphic bands. The selected 571 polymorphic SSR primer pairs and 35 EST-based SSR(eSSR) primer pairs developed at our laboratory were used to genotype 240 F1 individuals derived from a cross between Luoxushu 8 and Zhengshu 20. A double pseudo-test-cross strategy was applied for linkage analysis. The Luoxushu 8 map included 90 linkage groups with 5057 SSR markers and covered 13,299.9 cM with a marker density of 2.6 cM, and the Zhengshu 20 map contained 90 linkage groups with 3009 SSR markers and covered 11,122.9 cM with a marker density of 3.7 cM. Fifteen homologous groups were identified in both parent maps. These are the first SSR linkage maps consisting of the complete 90 linkage groups and 15 homologous groups, which are consistent with the autohexaploid nature of sweetpotato, and are also the linkage maps with the highest SSR marker density reported to date.These results provide a basis for QTL mapping, marker-assisted breeding and comparative genomics research of sweet potato.

Identification and fine mapping of qSW2 for leaf slow wilting in soybean

Drought is one of the abiotic stresses limiting the production of soybean(Glycine max).Elucidation of the genetic and molecular basis of the slow-wilting(SW)trait of this crop offers the prospect of its genetic improvement.A panel of 188 accessions and a set of recombinant inbred lines produced from a cross between cultivars Liaodou 14 and Liaodou 21 were used to identify quantitative-trait loci(QTL)associated with SW.Plants were genotyped by Specific-locus amplified fragment sequencing and seedling leaf wilting was assessed under three water-stress treatments.A genome-wide association study identified 26 SW-associated single-nucleotide polymorphisms(SNPs),including three located in a 248-kb linkage-disequilibrium(LD)block on chromosome 2.Linkage mapping revealed a major-effect QTL,qSW2,associated with all three treatments and adjacent to the LD block.Fine mapping in a BC_(2)F_(3) population derived from a backcross between Liaodou 21 and R26 confined qSW2 to a 60-kb interval.Gene expression and sequence variation analysis identified the gene Glyma.02 g218100,encoding an auxin transcription factor,as a candidate gene for qSW2.Our results will contribute significantly to improving drought-resistant soybean cultivars by providing genetic information and resources.

A genetic linkage map of marine shrimp Penaeus (Fenneropenaeus) chinensis based on AFLP, SSR, and RAPD markers

The Chinese shrimp Penaeus (Fenneropaeneus) chinensis is an important species in marine fishery and aquaculture in China. A female Chinese shrimp Penaeus (Fenneropaeneus) chinensis was captured from west coast of the Korean peninsula and mated with a "Yellow Sea No. 1" male to produce the first filial generation (F1) 100 F2 full-sib progeny from brother-sister crosses between F1 families was used for the mapping study. A genetic linkage map of the Chinese shrimp was constructed, based on 354 markers, including 300 amplified fragment length polymorphism (AFLP) markers, 42 microsatellite (SSR) markers, and 12 randomly amplified polymorphism (RAPD) markers. Forty-seven linkage groups (LGs) were identified. The total map length was 4 580.5 cM, with an average spacing of 11.3 cM, covering 75.8% of the estimated genome size. The construction of this genetic linkage map was part of a genetic breeding program. This linkage map will contribute to the discovery of genes and quantitative trait loci (QTLs) in Chinese shrimp.

An AFLP Genetic Linkage Map of Pacific Abalone(Haliotis discus hannai)

A genetic linkage map of Pacific abalone(Haliotis discus hannai) was constructed using AFLP markers based on a two-way pseudo-testcross strategy in a full-sib family. With 33 primer combinations,a total of 455 markers(225 from the female parent and 230 from the male parent) segregated in a 1:1 ratio,corresponding to DNA polymorphism:heterozygous in one parent and null in the other. The female framework map consisted of 174 markers distributed in 18 linkage groups,equivalent to the H. discus hannai haploid chromosome number,and spanning a total length of 2031.4 cM,with an average interval of 13.0 cM between adjacent markers. The male framework map consisted of 195 markers mapped on 19 linkage groups,spanning a total length of 2273.4 cM,with an average spacing of 12.9 cM between adjacent markers. The estimated coverage for the framework linkage maps was 81.2% for the female and 82.1% for the male,on the basis of two estimates of genome length. Fifty-two markers(11.4%) remained unlinked. The level of segregation distortion observed in this cross was 20.4%. These linkage maps will serve as a starting point for linkage studies in the Pacific abalone with potential application for marker-assisted selection in breeding programs.

Identification of the candidate gene controlling tiller angle in common wheat through genome-wide association study and linkage analysis

Wheat tiller angle(TA)is an important agronomic trait that contributes to grain production by affecting plant architecture.It also plays a crucial role in high-yield wheat breeding.An association panel and a recombinant inbred line(RIL)population were used to map quantitative trait loci(QTL)for TA.Results showed that 470 significant SNPs with 10.4%–28.8%phenotypic variance explained(PVE)were detected in four replicates by a genome-wide association study(GWAS).Haplotype analysis showed that the TA_Hap_4B1 locus on chromosome 4B was a major QTL to regulate wheat TA.Ten QTL were totally detected by linkage mapping with the RIL population,and QTA.hau-4B.1 identified in six environments with the PVE of 7.88%–18.82%was a major and stable QTL.A combined analysis demonstrated that both TA_Hap_4B1 and QTA.hau-4B.1 were co-located on the same region.Moreover,QTA.hau-4B.1 was confirmed by bulked segregant RNA-Seq(BSR-Seq)analysis.Phenotypic analysis showed that QTA.hau-4B.1was also closely related to yield traits.Furthermore,Traes CS4B02G049700 was considered as a candidate gene through analysis of gene sequence and expression.This study can be potentially used in cloning key genes modulating wheat tillering and provides valuable genetic resources for improvement of wheat plant architecture.