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.     

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.     

Molecular Marker-Assisted Dissection of Quantitative Trait Loci for seven Morphological Traits in Rice (Oryza Sativa L.)

Summary The genetic dissection of morphological traits can helpful to evaluate their potential values as markers for rice genetic improvement. In this study, a RI population derived from a cross from Zhenshan97 and IRAT109 was used to dissect the genetic bases of seven morphological traits such as leaf sheath color (LSC), grain apiculus color (GAC), grain hairiness density (GHD), grain awn length (GAL), ratio of leaf length to width (RLW), leaf erectness (LER) and natural leaf rolling status (NLR). Totally, 26 main-effect QTLs and 22 epistatic QTLs were detected. Of them, 11 main-effect and 3 epistatic QTLs expressed environmental interactions. GAC controlled by a single gene could be regarded as the most useful marker. LSC controlled by two major interacted main-effect QTLs, but with no environmental interaction, is suitable to become morphological marker. LSC will be a very efficient morphological marker for identification of hybrid plants at rice seedling stage when the two major QTLs are introduced into male sterile line and restorer line separately. GHD controlled by a major QTL and a few minor QTLs with comparative low QEIs could also be used as marker. The traits GAL, NLR, RLW and LER, which were controlled by a number of minor effect QTLs and affected by environmental conditions could not be used as marker. But the QTLs with large effects, such as nrl8, can be targeted for corresponding trait improvement through marker-aided selection in rice breeding.     

利用BC2F2高代回交群体定位水稻籽粒大小和形状QTL

以我国优良籼稻恢复系蜀恢527为轮回亲本, 以来自菲律宾的Milagrosa为供体亲本, 培育了样本容量为199株的BC₂F₂高代回交群体。选取85个均匀分布在12条染色体上的多态性SSR标记进行基因型分析, 同时对粒长、粒宽、长宽比和千粒重4种性状进行了表型鉴定。采用性状－标记间的单向和双向方差分析对上述性状进行了QTL定位。单向方差分析(P<0.01)共检测到了10个控制粒长、粒宽、长宽比和千粒重的QTL, 其中有3个具有多效性。由于粒长和长宽比的高度相关性, 控制长宽比的2个QTL均能在粒长QTL中检测到。位于第3染色体着丝粒区域的qgl3b是一个控制粒长、长宽比和千粒重的主效QTL, 它可以分别解释粒长、长宽比和千粒重表型变异的29.37%、26.15%和17.15%。该QTL对于粒长、长宽比和千粒重均表现较大的加性效应(来自蜀恢527的等位基因为增效)和负向超显性。位于第8染色体的qgw8位点是一个控制粒宽的主效QTL, 同时也是控制千粒重的微效QTL, 能解释粒宽表型变异的21.47%和千粒重表型变异的5.16%。该QTL对粒宽和千粒重均具有较大的加性效应(来自蜀恢527的等位基因为增效)和正向部分显性。双向方差分析(P<0.005)共检测到61对显著的上位性互作, 涉及54个QTL, 其中23个是能同时影响2~4个性状的多效位点, 且有8个位点与单向方差分析检测到的相同。控制长宽比的13对上位性互作位点中, 与控制粒长的上位性互作位点完全相同的有8对。以上结果为进一步开展水稻籽粒大小和形状有利基因的精细定位、克隆和分子设计育种奠定了基础。     

Identification of chromosome regions conferring dry matter accumulation and photosynthesis in wheat (<Emphasis Type="Italic">Triticum</Emphasis> <Emphasis Type="Italic">aestivum</Emphasis> L.)

Dry matter accumulation (DMA) and photosynthetic capacity are important traits that influence biological yield and ultimate grain yield in wheat. In this study, quantitative trait loci (QTLs) analyses for DMA of stem, leaves, total plant and photosynthesis traits (Fv/Fm) at the jointing and anthesis stages were studied, using a set of 168 doubled haploid lines (DHLs) derived from the cross Huapei 3 (HP3)/Yumai 57 (YM57). QTL analyses were performed using QTL-Network 2.0 software based on the mixed linear model approach. A total of 18 additive QTLs and 12 pairs of epistatic QTLs were distributed on 16 of the 21 chromosomes. Most of the additive QTLs associated with DMA co-located in the same or adjacent chromosome intervals with QTLs for grain yield and related traits. A major locus Qculmc.sau-5D.1 (14.2%) close to the molecular marker Xwmc215 detected at the jointing stage was shared by QTLs for heading date and vernalization sensitivity, indicating tight linkages or pleiotropisms. One pair of epistatic QTLs, Qleavesc.sau-4A and Qleavesc.sau- 6B, explained 13.11% of the phenotypic variation at anthesis. All QTL × environment interactions were detected at the jointing stage, showing the importance of the jointing stage in determining the final outcome of plant development.     

利用BC2F2高代回交群体定位水稻籽粒大小和形状QTL

以我国优良籼稻恢复系蜀恢527为轮回亲本, 以来自菲律宾的Milagrosa为供体亲本, 培育了样本容量为199株的BC₂F₂高代回交群体。选取85个均匀分布在12条染色体上的多态性SSR标记进行基因型分析, 同时对粒长、粒宽、长宽比和千粒重4种性状进行了表型鉴定。采用性状－标记间的单向和双向方差分析对上述性状进行了QTL定位。单向方差分析(P<0.01)共检测到了10个控制粒长、粒宽、长宽比和千粒重的QTL, 其中有3个具有多效性。由于粒长和长宽比的高度相关性, 控制长宽比的2个QTL均能在粒长QTL中检测到。位于第3染色体着丝粒区域的qgl3b是一个控制粒长、长宽比和千粒重的主效QTL, 它可以分别解释粒长、长宽比和千粒重表型变异的29.37%、26.15%和17.15%。该QTL对于粒长、长宽比和千粒重均表现较大的加性效应(来自蜀恢527的等位基因为增效)和负向超显性。位于第8染色体的qgw8位点是一个控制粒宽的主效QTL, 同时也是控制千粒重的微效QTL, 能解释粒宽表型变异的21.47%和千粒重表型变异的5.16%。该QTL对粒宽和千粒重均具有较大的加性效应(来自蜀恢527的等位基因为增效)和正向部分显性。双向方差分析(P<0.005)共检测到61对显著的上位性互作, 涉及54个QTL, 其中23个是能同时影响2~4个性状的多效位点, 且有8个位点与单向方差分析检测到的相同。控制长宽比的13对上位性互作位点中, 与控制粒长的上位性互作位点完全相同的有8对。以上结果为进一步开展水稻籽粒大小和形状有利基因的精细定位、克隆和分子设计育种奠定了基础。     

QTL analysis of main and epistatic effects for flour color traits in durum wheat

The aim of this work was to map quantitative trait loci (QTLs) associated with flour yellow color (Fb*) and yellow pigment content (YPC) in durum wheat (Triticum turgidum L. var. durum). Additionally, QTLs affecting flour redness (Fa*) and brightness (FL*) color parameters were investigated. A population of 93 RILs (UC1113 × Kofa) was evaluated in three locations of Argentina over 2 years. High heritability values (>94%) were obtained for Fb* and YPC, whereas FL* and Fa* showed intermediate to high values. The main QTLs affecting Fb* and YPC overlapped on chromosome arms 4AL (4AL.2), 6AL (6AL.2), 7AS, 7AL, 7BS (7BS.2) and 7BL (7BL.2). The 7BL.1 QTL included the Psy-B1 locus, but one additional linked QTL was detected. A novel minor QTL located on 7AS affected Fb*, with an epistatic effect on YPC. An epistatic interaction occurred between the 7AL and 7BL.2 QTLs. The 4AL.2 QTL showed a strong effect on Fb* and was involved in two digenic epistatic interactions. The 6AL.2 QTL explained most of the variation for Fb* and YPC. The main QTLs affecting FL* and Fa* were located on 2BS and 7BL, respectively. These results confirm the complex inheritance of flour color traits and open the possibility of developing perfect markers to improve pasta quality in Argentinean breeding programs.     

Comparison and analysis of main effects,epistatic effects,and QTL × environment interactions of QTLs for agronomic traits using DH and RILs populations in rice

Two genetic linkage maps based on doubled haploid (DH) and recombinant inbred lines (RILs) populations, derived from the same indica-japonica cross ‘Samgang × Nagdong’, were constructed to analyze the quantitative trait loci (QTLs) affecting agronomic traits in rice. The segregations of agronomic traits in RILs population showed larger variations than those in DH population. A total of 10 and 12 QTLs were identified on six chromosomes using DH population and seven chromosomes using RILs population, respectively. Three stable QTLs including pl9.1, ph1.1, and gwp11.1 were detected through different years. The percentages of phenotypic variation explained by individual QTLs ranged from 8 to 18% in the DH population and 9 to 33% in the RILs population. Twenty-three epistatic QTLs were identified in the DH population, while 21 epistatic QTLs were detected in the RILs population. Epistatic interactions played an important role in controlling the agronomic traits genetically. Four significant main-effect QTLs were involved in the digenic interactions. Significant interactions between QTLs and environments (QE) were identified in two populations. The QTLs affecting grain weight per panicle (GWP) were more sensitive to the environmental changes. The comparison and QTLs analysis between two populations across different years should help rice breeders to comprehend the genetic mechanisms of quantitative traits and improve breeding programs in marker-assisted selection (MAS).     

QTL identification for molecular breeding of fibre yield and fibre quality traits in jute

In jute (Corchorus olitorius), quantitative trait loci (QTL) analysis was conducted to study the genetics of eight fibre yield traits and two fibre quality traits. For this purpose, we used a mapping population consisting of 120 recombinant inbred lines (RILs) and also used a linkage map consisting of 36 SSR markers that was developed by us earlier (Das et al. 2011). The RIL population was derived from the cross JRO 524 (coarse fibre) × PPO4 (fine fibre) following single seed descent. Using single-locus analysis involving composite interval mapping, a total of 21 QTLs were identified for eight fibre yield traits whereas for fibre quality (fibre fineness), only one QTL was detected. The QTL for fibre fineness explained 8.31–10.56% of the phenotypic variation and was detected in two out of three environments. Using two-locus analysis involving QTLNetwork, as many as 11 M-QTLs were identified for seven fibre yield traits (excluding top diameter) and one M-QTL was identified for fibre fineness which accounted for 4.57% of the phenotypic variation. For six fibre yield traits, we detected 16 E-QTLs involved in nine QQ epistatic interactions. For fibre fineness, four E-QTLs involved in two QQ epistatic interactions and for fibre strength, six E-QTLs involved in three QQ epistatic interactions were identified. Eight out of the 11 M-QTLs observed for the fibre yield traits were also involved in QE interactions; for fibre fineness and fibre strength, no QE interactions were observed.     

Upland rice breeding in Brazil: a simultaneous genotypic evaluation of stability, adaptability and grain yield

A durum wheat recombinant inbred line population developed from PDW 233 × Bhalegaon 4 cross was analyzed in five environments to understand the genetic network responsible for test weight (TW), thousand kernel weight (TKW), grain yield (YLD), spike length (SL), spikelets per spike (SPS), kernels per spike (KER) and kernel weight per spike (KWS). Genotype, environment and their interactions were main sources of variance for all the traits. TW and TKW were influenced by 11 main effect QTL and 6 digenic epistatic interactions detected on chromosomes 2A, 2B, 4B and 7A. Grain yield was influenced by three epistatic interactions and five main effect QTL, of which two on chromosome 2A were most consistent. A major QTL for spike length was observed on chromosome 3B. QTL for spike characters were distributed over 9 chromosomes. All the traits showed significant influence of digenic epistasis (QQ) and, to a certain extent, QTL × environment interactions (QQE). Therefore, while breeding for complex traits like kernel characters and grain yield components, these interactions should also be considered important. The consistent QTL on chromosome 2A between the marker interval Xgwm71.2–Xubc835.4 with pleiotropic effect on TW and TKW, may be utilized in early generation selection to improve TW and TKW and thereby the milling potential of the durum wheat.     

Identification and multiple comparisons of QTL and epistatic interaction conferring high yield under boron and phosphorus deprivation in Brassica napus

Boron (B) and phosphorus (P) are two essential nutrients for plants. To unravel the genetic basis of B and P efficiency in Brassica napus, quantitative trait locus (QTL) and epistatic interaction analysis for yield and yield-related traits under contrast B and P conditions were performed using two mapping populations across various environments. Main effect QTLs were detected by QTLNetwork and QTL Icimapping (ICIM), and were compared with our previously reported main effect QTLs identified by QTLCartographer. Epistatic QTLs were identified by QTLNetwork, ICIM and Genotype matrix mapping (GMM), and multiple comparisons of main effect QTLs and epistatic QTLs were conducted. For the two mapping populations, 51 main effect QTLs were identified by QTLNetwork, 106 by ICIM. Among them, 35 main effect QTLs were simultaneously identified by three programs. Moreover, 578, 18 and 62 epistatic QTLs were identified by GMM, QTLNetwork and ICIM, respectively. Interestingly, a total of 235 epistatic QTLs identified by GMM were associated with 50 main effect QTLs identified by three programs. However, only nine epistatic QTLs identified by QTLNetwork and ICIM were involved in main effect QTLs. Twenty-two main effect QTLs in the BERIL population overlapped with 20 main effect QTLs for the same traits in the BQDH population, but no main effect QTLs were detected both under P and B stress environments, indicating the genetic differences in B and P homeostasis in B. napus. By in silico mapping, 29 candidate genes were located in the consensus QTL intervals. This study suggested the availability of dissecting genetic basis for complex traits under B/P deficiency by analyzing main effect QTLs and epistatic QTLs using multiple programs across different environments. The robust main effect QTLs and epistatic QTLs associated could be useful in breeding B and P efficient cultivars of B. napus.     

Molecular genetic analysis of flour color using a doubled haploid population in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Flour color is an important trait in the assessment of flour quality for the production of many end products. In this study, quantitative trait loci (QTLs) with additive effects, epistatic effects, and QTL × environment (QE) interactions for flour color in bread wheat (Triticum aestivum L.) were studied, using a set of 168 doubled haploid (DH) lines derived from a Huapei 3 × Yumai 57 cross. A genetic map was constructed using 283 simple sequence repeats (SSR) and 22 expressed sequence tags (EST)-SSR markers. The DH and parents were evaluated for flour color in three environments. QTL analyses were performed using QTLNetwork 2.0 software based on a mixed linear model approach. A total of 18 additive QTLs and 24 pairs of epistatic QTLs were detected for flour color, which were distributed on 19 of the 21 chromosomes. One major QTL, qa1B, closely linked to barc372 0.1 cM, could account for 25.64% of the phenotypic variation of a* without any influence from the environments. So qa1B could be used in the molecular marker-assisted selection (MAS) in wheat breeding programs. The results showed that both additive and epistatic effects were important genetic basis for flour color, and were also sometimes subject to environmental modifications. The information obtained in this study should be useful for manipulating the QTLs for flour color by MAS in wheat breeding programs. Kun-Pu Zhang and Guang-Feng Chen contributed equally to this study.     

Genetic studies of seed longevity in hexaploid wheat using segregation and association mapping approaches

Xieyou9308 is the first commercial super hybrid rice released in 1996 in China. To clarify its genetic mechanism underlying high yield potential, a recombinant inbred line (RIL) population derived from the cross between the maintainer line XieqingzaoB (XQZB) and the restorer line Zhonghui9308 (ZH9308) and two derived backcross F₁ (BCF₁) populations were developed for the identification of quantitative trait loci (QTLs) related to ten important agronomic traits (tiller number (TN), heading date (HD), and grain yield per plant (GYPP), etc.). The BCF₁ performance was closely correlated with the performance of their parental RILs according to both the analysis of broad-sense heritability (h _B ²) and phenotypic correlation coefficient (PCC) in the two BCF₁ populations, but not proved by QTL analysis. A total of 21 additive-effect main QTLs (M-QTLs), 22 dominant-effect M-QTLs, and 19 dominant-effect M-QTLs were detected with the WinQTLCart 2.50 software for the ten traits in the RIL and two BCF₁ populations, respectively. Of theses, three QTLs (qHD7a, qPPP3a, and qPL10) of 21 were detected repeatedly in the RIL and one BCF₁ populations, ten QTLs underlying four traits were only detected repeatedly in two BCF₁ populations, and nine QTLs controlling more than two traits were detected repeatedly, the additive-effect QTLs and dominant-effect QTLs play an important role in the performance of agronomic traits and no epistatic QTL of additive by additive effect and dominant by dominant-effect was detected for all traits in three populations. This research is valuable for M-QTL related to important agronomic trait in future fine mapping and positional cloning.     

Transgressive segregation due to linked QTLs for grain characteristics of rice

Summary It has been theoretically proposed that multiple linked quantitative trait loci (QTLs) play a role in the accumulation of hidden variation within and between populations. In this study, the genetic bases for grain characteristics were examined by comparing two accessions representing the two rice subspecies by QTL analysis. Grain dimensions are known to be quantitative traits and to be diagnostic between these two subspecies. To enhance the power to detect QTL with small effects, after transferring a segment of chromosome 6 from an Indica type into a Japonica type of rice by repeated backcrosses, the introgressed segment was dissected by making recombinant inbred lines (RILs) which were expected to have different sizes of the introgressed segment in the same genetic background. The resulting RILs showed distinct transgression of the grain characteristics examined. Multiple QTLs controlling each of the length and breadth of seeds were detected on the introgressed segment, and showed positive and negative additive effects as well as epistatic interactions. The present study confirmed that transgressive segregation resulted from a breakdown of linkage and that the detection of QTLs was highly dependent upon the genetic effects of the neighboring QTLs, indicating the need for caution in interpreting QTL effects.     

多环境下水稻DH群体剑叶长度的QTL分析

种植由籼稻品种和粳稻品种杂交衍生的DH群体,连续4年测定剑叶长度,运用基于混合模型的复合区间作图法,定位其QTL及上位性互作,估算遗传主效应和环境互作效应。结果表明,全部18个QTL都参与了上位性的形成,其中3个没有自身的遗传效应,但参与了3对上位性互作,这是传统方法不能发现的。另外,一个QTL可与多个QTL发生互作,这可能预示着存在更高阶互作。QTL与上位性互作可以具有不受环境影响而稳定表达的效应,以及与环境的互作效应。有些QTL与环境的互作效应可以在多环境下被检测到,但却不具有主效应,这种QTL可能易受环境因子的影响。QTL与环境的互作效应为随机效应,一个QTL或一对上位性与环境的互作效应总和理论上应等于零,否则会影响对遗传效应的估算,因此多环境下估算的遗传效应更可靠。     

Identification and application of major quantitative trait loci for panicle length in rice (Oryza sativa) through single‐segment substitution lines

Panicle length (PL), an important yield‐related trait, strongly affects yield components, such as grain number, grain density and rice quality. More than 200 panicle length quantitative trait loci (PL QTLs) are identified, but only a small number are applied in rice breeding. In this study, we performed QTL analysis for PL using 42 single‐segment substitution lines (SSSLs) derived from nine donors in the genetic background of HJX74. Fourteen QTLs and five heterosis QTLs (HQTLs) for PL were recognised. Three QTLs and four HQTLs acted positively, and the other eleven QTLs and one HQTL acted negatively. By scanning the single heterozygous background region of the F₂ population with large‐genetic‐effect SSSLs, we mapped PL loci qPL6‐2 and qPL7‐1 to different locations on chromosomes 6 and 7, respectively, in three consecutive years of independent trials. The genetic effects of these QTLs were further assessed. qPL6‐2 demonstrated the most positive additive effect (QTL), whereas qPL7‐1 achieved the most positive dominant effect (HQTL) for PL. These results indicated that the pyramiding of PL QTLs might increase grain yield and facilitate the application of the beneficial allele in hybrid rice breeding.     

Novel quantitative trait loci for yield and yield related traits identified in Basmati rice (Oryza sativa)

Increasing crop productivity is one of the prime goals of crop breeding research. Rice grain yield is a complex quantitative trait governed by polygenes. Although several QTLs governing grain yield traits have been reported and limited attempts have been made to map QTLs for grain yield parameters in Basmati rice. A population from the cross Sonasal and Pusa Basmati 1121 comprising 352 RILs was generated through the single seed descent method. A total of 12 QTLs governing yield and yield-related traits were mapped on six chromosomes, namely, 1, 2, 3, 7, 8 and 9, of which five QTLs were novel. We identified a novel and robust epistatic QTL (qPH1.1 and qPL1.1) governing plant height and panicle length, flanked by the markers RM5336-RM1 on chromosome 1. The gene encoding brassinosteroid insensitive 1-associated receptor kinase 1 precursor is the putative candidate gene underlying this epistatic QTL. Another novel QTL, qNT3.1, governing tiller number was bracketed to a region of .77 Mb between the markers RM15247 and RM15281 on chromosome 3. Of the 57 annotated gene models, Os03g0437600 encoding alpha/beta-fold hydrolase, a homologous to AtKai2 is a putative candidate gene underlying the novel QTL qNT3.1. The other QTLs such as qDFF1.1 governing days to 50% flowering co-localizes with the gene Ghd7, QTL for plant height qPH1.2 co-localizes with the gene sd1, the QTLs for panicle length co-localizes with FUWA and DEP2, the QTL for tiller number co-localizes with OsRLCK57 and QTLs for thousand-grain weight co-localize with the major gene GS3. The QTLs identified in the current study can be effectively used in marker-assisted selection for developing Basmati rice varieties with a higher yield.     

QTL analysis of quality traits in the spring wheat cross RL4452 × 'AC Domain'

Wheat grain quality is a complex group of traits of tremendous importance to wheat producers, end‐users and breeders. Quantitative trait locus (QTL) analysis studied the genetics of milling, mixograph, farinograph, baking, starch and noodle colour traits in the spring wheat population RL4452/‘AC Domain’. Forty‐seven traits were measured on the population and 99 QTLs were detected over 18 chromosomes for 41 quality traits. Forty‐four of these QTLs mapped to three major QTL clusters on chromosomes 1B, 4D, and 7D. Fourteen QTLs mapped near Glu‐B1, 20 QTLs mapped near a major plant height QTL on chromosome 4D, and 10 QTLs mapped near a major time to maturity QTL on chromosome 7D. Large QTLs were detected for grain and flour protein content, farinograph absorption, mixograph parameters, and dietary fibre on chromosome 2BS. QTLs for yellow alkaline noodle colour parameter L* mapped to chromosomes 5B and 5D, while the largest QTL for the b* parameter mapped to 7AL.     

QTL analysis of textural property traits for Chinese northern-style steamed bread

Quantitative trait loci (QTLs) influencing textural properties (hardness, adhesiveness, springiness, cohesiveness, gumminess, chewiness, and resilience)of wheat for Chinese northern-style steamed bread were studied using a doubled haploid (DH) population containing 168 lines derived from a cross between elite Chinese wheat cultivars Huapei 3 and Yumai 57 (Triticum aestivum L.). The DH population and parents were grown in 2007 and 2008 in Tai’an and 2008 in Suzhou. QTL analyses were performed using the software QTL Network version 2.0 and IciMapping v2.2 based on the mixed linear model. Thirty nine putative QTLs were detected on 14 chromosomes: viz. 1A, 2A, 3A, 4A, 6A, 1B, 2B, 3B, 5B, 6B, 7B, 5D, 6D, and 7D, and single QTLs explained 3.91–35.17% of the phenotypic variation. Eight pairs of QTLs with epistatic effects and/or epistasis × environment (AAE) effects were detected for adhesiveness, resilience, hardness, and cohesiveness on chromosomes 2A, 1B and 3D. Several co-located QTLs with additive effects were detected on chromosomes 2B, 5D, 6A, 3A, 3B and 6D. Two clusters of three QTLs for steamed bread textural properties (chewiness, gumminess, and hardness) and for adhesiveness, cohesiveness and resilience were detected on chromosome 2B. Two co-located QTLs with epistatic effects were detected on chromosomes 1B and 3A. Both additive effects and epistatic effects were important for Chinese steamed bread textural properties, which were also subject to environmental modifications. The information obtained in this study will be useful for manipulating QTLs determining Chinese steamed bread textural properties by molecular marker-assisted selection.