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Studying the regulatory mechanisms that drive nitrogen-use efficiency (NUE) in crops is important for sustainable agriculture and environmental protection. In this study, we generated a high-quality genome assembly for the high-NUE wheat cultivar Kenong 9204 and systematically analyzed genes related to nitrogen uptake and metabolism. By comparative analyses, we found that the high-affinity nitrate transporter gene family had expanded in Triticeae. Further studies showed that subsequent functional differentiation endowed the expanded family members with saline inducibility, providing a genetic basis for improving the adaptability of wheat to nitrogen deficiency in various habitats. To explore the genetic and molecular mechanisms of high NUE, we compared genomic and transcriptomic data from the high-NUE cultivar Kenong 9204 (KN9204) and the low-NUE cultivar Jing 411 and quantified their nitrogen accumulation under high- and low-nitrogen conditions. Compared with Jing 411, KN9204 absorbed significantly more nitrogen at the reproductive stage after shooting and accumulated it in the shoots and seeds. Transcriptome data analysis revealed that nitrogen deficiency clearly suppressed the expression of genes related to cell division in the young spike of Jing 411, whereas this suppression of gene expression was much lower in KN9204. In addition, KN9204 maintained relatively high expression of NPF genes for a longer time than Jing 411 during seed maturity. Physiological and transcriptome data revealed that KN9204 was more tolerant of nitrogen deficiency than Jing 411, especially at the reproductive stage. The high NUE of KN9204 is an integrated effect controlled at different levels. Taken together, our data provide new insights into the molecular mechanisms of NUE and important gene resources for improving wheat cultivars with a higher NUE trait. A high-quality genome assembly of the high-NUE wheat cultivar Kenong 9204 was generated and genes related to nitrogen uptake and metabolism were systematically analyzed. Genomic and transcriptomic comparative analyses of Kenong 9204 with the low-NUE cultivar Jing 411 revealed key developmental stages and associated metabolic pathways responsible for N status, as well as possible molecular mechanisms that drive NUE in wheat. [ABSTRACT FROM AUTHOR]

As an important component of wheat (Triticum aestivum L.) yield, 1000‐kernel weight (TKW) has played a crucial role in yield improvement in recent decades. Marker‐assisted selection is an effective tool for improving quantitative traits; however, most markers have not been effectively applied in TKW improvement despite the identification of many loci associated with TKW. In this study, association mapping was performed using local cultivated varieties, and a previous linkage analysis was integrated to identify 10 candidate intervals. The corresponding kompetitive allele‐specific PCR markers associated with TKW were successfully developed and screened in 1153 F4 breeding lines. Three markers, namely, Ktkw‐5B2, Ktkw‐5D, and Ktkw‐7D, were proved to be significantly related to TKW according to large‐scale association mapping, and their ability to increase TKW was enhanced in combination. We applied the three markers in 150 F6 breeding lines and obtained 25 high‐TKW lines, indicating the availability in marker‐assisted selection. The TKW‐increasing allele for Ktkw‐5D was heavily selected in the present breeding program, while that for Ktkw‐5B2 was low and for Ktkw‐7D tended to increase after 2000. Furthermore, strategies for gene exploration in the three significant intervals were proposed. These results are expected to provide an efficient route for improving TKW in wheat high‐yield breeding. Core Ideas: Three significant loci for 1000‐kernel weight were identified by genetic analysis.The markers were applied in breeding lines to generate varieties with high 1000‐kernel weight.The application progress of the three loci was clarified.Strategies for gene exploration in the three significant intervals were proposed. [ABSTRACT FROM AUTHOR]

Key message: QTLs for kernel characteristics and tolerance to N stress were identified, and the functions of ten known genes with regard to these traits were specified. Abstract: Kernel size and quality characteristics in wheat ( Triticum aestivum L.) ultimately determine the end use of the grain and affect its commodity price, both of which are influenced by the application of nitrogen (N) fertilizer. This study characterized quantitative trait loci (QTLs) for kernel size and quality and examined the responses of these traits to low-N stress using a recombinant inbred line population derived from Kenong 9204 × Jing 411. Phenotypic analyses were conducted in five trials that each included low- and high-N treatments. We identified 109 putative additive QTLs for 11 kernel size and quality characteristics and 49 QTLs for tolerance to N stress, 27 and 14 of which were stable across the tested environments, respectively. These QTLs were distributed across all wheat chromosomes except for chromosomes 3A, 4D, 6D, and 7B. Eleven QTL clusters that simultaneously affected kernel size- and quality-related traits were identified. At nine locations, 25 of the 49 QTLs for N deficiency tolerance coincided with the QTLs for kernel characteristics, indicating their genetic independence. The feasibility of indirect selection of a superior genotype for kernel size and quality under high-N conditions in breeding programs designed for a lower input management system are discussed. In addition, we specified the functions of Glu- A1, Glu- B1, Glu- A3, Glu- B3, TaCwi- A1, TaSus2, TaGS2- D1, PPO- D1, Rht- B1, and Ha with regard to kernel characteristics and the sensitivities of these characteristics to N stress. This study provides useful information for the genetic improvement of wheat kernel size, quality, and resistance to N stress. [ABSTRACT FROM AUTHOR]

Flag leaf-related traits (FLRTs) are determinant traits affecting plant architecture and yield potential in wheat (Triticum aestivum L.). In this study, a recombinant inbred line population with 188 lines, derived from the cross between Kenong9204 and Jing411, was developed to identify quantitative trait loci (QTL) for flag leaf width (FLW), length (FLL), and area (FLA) under both low nitrogen and high nitrogen treatments. A total of 38 QTLs were detected in eight environments (year × location × treatment). Of these, two QTLs for FLW on chromosomes 4B and 6B (qFlw-4B.3 and qFlw-6B.2) and one for FLA on chromosome 5B (qFla-5B) were major stable QTLs. Both phenotypic and QTL mapping analyses indicated that FLW was the major contributor to flag leaf size. To investigate the genetic relationship between FLRTs and yield-related traits (YRTs) at the QTL level, both unconditional and multivariable conditional QTL mapping for YRTs with respect to FLRTs were conducted. Twelve QTL clusters simultaneously controlling FLRTs and YRTs were identified. In comparison with unconditional QTL mapping, conditional QTL mapping analysis revealed that most but not all the QTL for YRTs were improved by FLRTs. At the QTL level, FLA had the greatest contribution to YRTs, followed by FLW and FLL. This study provided a genetic foundation from which to obtain desirable plant architecture and improve yield potential in wheat breeding programs. [ABSTRACT FROM AUTHOR]

In order to detect quantitative trait loci (QTLs) for drought tolerance in wheat during seed germination conditional and unconditional QTL analyses of eight seedling traits were conducted under two water regimes using three related F recombinant inbred line populations with a common female parent. A total of 87 QTLs for the eight seedlings traits and 34 specific QTLs related to drought tolerance were detected. Seventy-one of these QTLs were major QTLs with contributions to phenotypic variance of >10 %. Of the 34 QTLs related to drought tolerance only eight were also detected by unconditional analysis of seedling traits under osmotic stress conditions indicating that most of the QTLs related to drought tolerance could not be detected by unconditional QTL analysis. Therefore, conditional QTL analysis of stress-tolerance traits such as drought tolerance was feasible and effective. Of 11 important QTL clusters located on chromosomes 1BL, 1D, 2A, 2B, 2D, 4A, 6B, and 7B, nine were detected in multiple populations and eight were detected by both unconditional and conditional analyses. [ABSTRACT FROM AUTHOR]

Key message: A novel high-density consensus wheat genetic map was obtained based on three related RIL populations, and the important chromosomal regions affecting yield and related traits were specified. Abstract: A prerequisite for mapping quantitative trait locus (QTL) is to build a genetic linkage map. In this study, three recombinant inbred line populations (represented by WL, WY, and WJ) sharing one common parental line were used for map construction and subsequently for QTL detection of yield-related traits. PCR-based and diversity arrays technology markers were screened in the three populations. The integrated genetic map contains 1,127 marker loci, which span 2,976.75 cM for the whole genome, 985.93 cM for the A genome, 922.16 cM for the B genome, and 1,068.65 cM for the D genome. Phenotypic values were evaluated in four environments for populations WY and WJ, but three environments for population WL. Individual and combined phenotypic values across environments were used for QTL detection. A total of 165 putative additive QTL were identified, 22 of which showed significant additive-by-environment interaction effects. A total of 65 QTL (51.5 %) were stable across environments, and 23 of these (35.4 %) were common stable QTL that were identified in at least two populations. Notably, QTkw- 5B.1, QTkw- 6A.2, and QTkw- 7B.1 were common major stable QTL in at least two populations, exhibiting 11.28-16.06, 5.64-18.69, and 6.76-21.16 % of the phenotypic variance, respectively. Genetic relationships between kernel dimensions and kernel weight and between yield components and yield were evaluated. Moreover, QTL or regions that commonly interact across genetic backgrounds were discussed by comparing the results of the present study with those of previous similar studies. The present study provides useful information for marker-assisted selection in breeding wheat varieties with high yield. [ABSTRACT FROM AUTHOR]

For discovering the quantitative trait loci (QTLs) contributing to early seedling growth and drought tolerance during germination, conditional and unconditional analyses of 12 traits of wheat seedlings: coleoptile length, seedling height, longest root length, root number, seedling fresh weight, stem and leaves fresh weight, root fresh weight, seedling dry weight, stem and leaves dry weight, root dry weight, root to shoot fresh weight ratio, root-to-shoot dry weight ratio, were conducted under two water conditions using two F recombinant inbred line (RIL) populations. The results of unconditional analysis are as follows: 88 QTLs accounting for 3.33-77.01% of the phenotypic variations were detected on chromosomes 1A, 1B, 1D, 2A, 2B, 2D, 3A, 3B, 4A, 4B, 4D, 5A, 5B, 5D, 6A, 6B, 6D, 7A, 7B and 7D. Among these QTLs, 19 were main-effect QTLs with a contribution rate greater than 10%. The results of the conditional QTL analysis of 12 traits under osmotic stress on normal water conditions were as follows: altogether 22 QTLs concerned with drought tolerance were detected on chromosomes 1B, 2A, 2B, 3B, 4A, 5D, 6A, 6D, 7B, and 7D. Of these QTLs, six were main-effect QTLs. These 22 QTLs were all special loci directly concerned with drought tolerance and most of them could not be detected by unconditional analysis. The finding of these QTLs has an important significance for fine-mapping technique, map-based cloning, and molecular marker-assisted selection of early seedling traits, such as growth and drought tolerance. [ABSTRACT FROM AUTHOR]

Spike length (SL), spikelet number (SPN) per spike, kernel number per spike (KNPS), and thousand-kernel weight (TKW) have strong genetic associations with kernel weight per spike (KWPS) in wheat. To investigate their genetic relationships at the individual quantitative trait locus (QTL) level, both unconditional and conditional QTL mapping for KWPS with respect to SL, SPN, KNPS, and TKW were conducted. Two related F recombinant inbred line populations, comprising 485 and 229 lines, respectively, were used. The trait phenotypic performances of each population were evaluated in four different environments. Unconditional QTL mapping analysis identified 22 putative additive QTL for KWPS, five of which were stable QTL, and only QKwps- WJ- 1B.2 showed significant additive-by-environment interaction effects. In comparison with unconditional QTL mapping analysis, conditional QTL mapping analysis indicated that, at the QTL level, KNPS and TKW contributed more to KWPS than did SL and SPN. Any unconditional QTL for KWPS detected in this study was associated with at least one of its four related traits. The present study will provide assistance in the understanding of the genetic relationships between KWPS and its related traits. [ABSTRACT FROM AUTHOR]

Grain protein content in wheat ( Triticum aestivum L.) is generally considered a highly heritable character that is negatively correlated with grain yield and yield-related traits. Quantitative trait loci (QTL) for protein content was mapped using data on protein content and protein content conditioned on the putatively interrelated traits to evaluate possible genetic interrelationships between protein content and yield, as well as yield-related traits. Phenotypic data were evaluated in a recombinant inbred line population with 302 lines derived from a cross between the Chinese cultivar Weimai 8 and Luohan 2. Inclusive composite interval mapping using IciMapping 3.0 was employed for mapping unconditional and conditional QTL with additives. A strong genetic relationship was found between protein content and grain yield, and yield-related traits. Unconditional QTL mapping analysis detected seven additive QTL for protein content, with additive effects ranging in absolute size from 0.1898% to 0.3407% protein content, jointly accounting for 43.45% of the trait variance. Conditional QTL mapping analysis indicated two QTL independent from yield, which can be used in marker-assisted selection for increasing yield without affecting grain protein content. Three additional QTL with minor effects were identified in the conditional mapping. Of the three QTLs, two were identified when protein content was conditioned on yield, which had pleiotropic effects on those two traits. Conditional QTL mapping can be used to dissect the genetic interrelationship between two traits at the individual QTL level for closely correlated traits. Further, conditional QTL mapping can reveal additional QTL with minor effects that are undetectable in unconditional mapping. [ABSTRACT FROM AUTHOR]

Spike-related traits contribute greatly to grain yield in wheat. To localize wheat chromosomes for factors affecting the seven spike-related traits-i.e., the spike length (SL), the basal sterile spikelet number (BSSN), the top sterile spikelet number (TSSN), the sterile spikelet number in total (SSN), the spikelet number per spike (SPN), the fertile spikelet number (FSN) and the spike density (SD)-two F recombinant inbred line (RIL) populations were generated. They were derived from crosses between Weimai 8 and Jimai 20 (WJ) and between Weimai 8 and Yannong 19 (WY), comprising 485 and 229 lines, respectively. Combining the two new linkage maps and the phenotypic data collected from the four environments, we conducted quantitative trait locus (QTL) detection for the seven spike-related traits and evaluated their genetic correlations. Up to 190 putative additive QTL for the seven spike-related traits were detected in WJ and WY, distributing across all the 21 wheat chromosomes. Of these, at least nine pairwise QTL were common to the two populations. In addition, 38 QTL showed significance in at least two of the four different environments, and 18 of these were major stable QTL. Thus, they will be of great value for marker assisted selection (MAS) in breeding programs. Though co-located QTL were universal, every trait owned its unique QTL and even two closely related traits were not excluded. The two related populations with a large/moderate population size made the results authentic and accurate. This study will enhance the understanding of the genetic basis of spike-related traits. [ABSTRACT FROM AUTHOR]

Abstract: 1BL/1RS translocations are widely used in wheat breeding programs. The present study aimed to determine the effect of the 1BL/1RS chromosome on agronomic traits and quality characteristics. A total of 485 and 20 recombinant inbred lines (RILs) were derived from the cross between Weimai 8 and Jimai 20. The 485 RILs planted in four environments were used for single marker analysis via IciMappingV3.1 based on 1RS-specific markers. 1RS was found to increase the spikelet number per spike and plant height, as well as decrease the 1000-grain weight, kernel hardness, and testweight. The 20 RILs planted in another four environments were evaluated in relation to agronomic traits and quality characteristics. The 1BL/1RS translocation showed a higher grain yield, above-ground biomass, plant height, kernel number per spike, and spikelet number per spike. However, the 1000-grain weight was lower. In contrast to the superior grain yield potential, the presence of 1BL/1RS had a significant negative effect on the milling quality, i.e., the kernel hardness and testweight were lower. The end-use quality was also negatively affected, i.e., the sedimentation volume and tractility were lower. The effects of 1BL/1RS on the spikelet number per spike, plant height, 1000-grain weight, kernel hardness, and testweight of the 20 RILs well agreed with those found from a quantitative trait locus analysis of 485 RILs. Although the 1BL/1RS translocation increased the grain yield, its negative effect on the quality could limit its commercial exploitation. The present study elucidated the effects of the 1BL/1RS chromosome on agronomic traits and quality characteristics. The findings serve as a foundation for the utilisation of 1BL/1RS translocations in wheat breeding programs. [Copyright &y& Elsevier]

Grain protein content (GPC) and gluten quality are the most important factors determining the end-use quality of wheat for pasta-making. Both GPC and gluten quality are considered to be polygenic traits influenced by environmental factors and other agricultural practices. Two related F recombinant inbred line (RIL) populations were generated to localise genetic factors controlling seven quality traits: GPC, wet gluten content (WGC), flour whiteness (FW), kernel hardness (KH), water absorption (Abs), dough development time (DDT) and dough stability time (DST). These lines were derived by crossing Weimai 8 and Jimai 20 (WJ) and by crossing Weimai 8 and Yannong 19 (WY). In total, WJ comprised 485 lines, while WY comprised 229 lines. Data on these seven quality traits were collected from each line in five different environments. Up to 85 putative QTLs for the seven traits were detected in WJ and 65 putative QTLs were detected in WY. Of these QTLs, 31 QTLs (36.47%) were detected in at least two trials in WJ, while 24 QTLs (36.92%) were detected in at least two trials in WY. Three QTLs from WJ and 25 from WY accounted for more than 10% of the phenotypic variance. The total 150 QTLs were spread throughout all 21 wheat chromosomes. Of these, at least thirteen pairwise were common to both populations, accounting for 20.00 and 15.29% of the total QTLs in WJ and WY, respectively. A major QTL for GPC, accounting for 53.04% of the phenotypic variation, was detected on chromosome 5A. A major QTL for WGC also shared this interval, explained more than 36% of the phenotypic variation, and was significant in two environments. Though co-located QTLs were common, every trait had its unique control mechanism, even for two closely related traits. Due to the different sizes of the two line populations, we also assessed the effects of population size on the efficiency and precision of QTL detection. In sum, this study will enhance our understanding of the genetic basis of these seven pivotal quality traits and facilitate the breeding of improved wheat varieties. [ABSTRACT FROM AUTHOR]

Kernel dimensions (KD) contribute greatly to thousand-kernel weight (TKW) in wheat. In the present study, quantitative trait loci (QTL) for TKW, kernel length (KL), kernel width (KW) and kernel diameter ratio (KDR) were detected by both conditional and unconditional QTL mapping methods. Two related F8:9 recombinant inbred line (RIL) populations, comprising 485 and 229 lines, respectively, were used in this study, and the trait phenotypes were evaluated in four environments. Unconditional QTL mapping analysis detected 77 additive QTL for four traits in two populations. Of these, 24 QTL were verified in at least three trials, and five of them were major QTL, thus being of great value for marker assisted selection in breeding programmes. Conditional QTL mapping analysis, compared with unconditional QTL mapping analysis, resulted in reduction in the number of QTL for TKW due to the elimination of TKW variations caused by its conditional traits; based on which we first dissected genetic control system involved in the synthetic process between TKW and KD at an individual QTL level. Results indicated that, at the QTL level, KW had the strongest influence on TKW, followed by KL, and KDR had the lowest level contribution to TKW. In addition, the present study proved that it is not all-inclusive to determine genetic relationships of a pairwise QTL for two related/causal traits based on whether they were co-located. Thus, conditional QTL mapping method should be used to evaluate possible genetic relationships of two related/causal traits. [ABSTRACT FROM AUTHOR]

Plant height (PH) in wheat is a complex trait; its components include spike length (SL) and internode lengths. To precisely analyze the factors affecting PH, two F recombinant inbred line (RIL) populations comprising 485 and 229 lines were generated. Crosses were performed between Weimai 8 and Jimai 20 (WJ) and between Weimai 8 and Yannong 19 (WY). Possible genetic relationships between PH and PH components (PHC) were evaluated at the quantitative trait locus (QTL) level. PH and PHC (including SL and internode lengths from the first to the fourth counted from the top, abbreviated as FIITL, SITL, TITL, and FOITL, respectively) were measured in four environments. Individual and the pooled values from four trials were used in the present analysis. A QTL for PH was mapped using data on PH and on PH conditioned by PHC using IciMapping V2.2. All 21 chromosomes in wheat were shown to harbor factors affecting PH in two populations, by both conditional and unconditional QTL mapping methods. At least 11 pairwise congruent QTL were identified in the two populations. In total, ten unconditional QTL and five conditional QTL that could be detected in the conditional analysis only have been verified in no less than three trials in WJ and WY. In addition, three QTL on the short arms of chromosomes 4B, 4D, and 7B were mapped to positions similar to those of the semi-dwarfing genes Rht- B1, Rht- D1 and Rht13, respectively. Conditional QTL mapping analysis in WJ and WY proved that, at the QTL level, SL contributed the least to PH, followed by FIITL; TITL had the strongest influence on PH, followed by SITL and FOITL. The results above indicated that the conditional QTL mapping method can be used to evaluate possible genetic relationships between PH and PHC, and it can efficiently and precisely reveal counteracting QTL, which will enhance the understanding of the genetic basis of PH in wheat. The combination of two related populations with a large/moderate population size made the results authentic and accurate. [ABSTRACT FROM AUTHOR]

Key message: The combination of a QTL on chromosome arm 4BL and Yr29 provides durable resistance with no significant yield penalty. Wheat stripe rust or yellow rust (YR), caused by Puccinia striiformis f. sp. tritici (Pst), causes substantial yield reductions globally, but losses can be minimized by using resistance genes. Chinese wheat cultivar Jing 411 (J411) has continued to display an acceptable level of adult-plant resistance (APR) to YR in varied field conditions since its release in the 1990s. A recombinant inbred line (RIL) population comprising 187 lines developed from a cross of J411 and Kenong 9204 (KN9204) was evaluated in multiple environments to identify genomic regions carrying genes for YR resistance. A total of five quantitative trait loci (QTL) on chromosome arm 1BL, 3BS, 4BL, 6BS, and 7BL from J411 and two QTL on 3DS and 7DL from KN9204 were detected using inclusive composite interval mapping with the wheat 660 K SNP array. QYr.nwafu-1BL.5 and QYr.nwafu-4BL.3 from J411 were robust and showed similar effects in all environments. QYr.nwafu-1BL.5 was likely the pleiotropic gene of Yr29/Lr46. QYr.nwafu-4BL.3 was located within a 1.0 cM interval delimited by KASP markers AX-111609222 and AX-89755491. Based on haplotype analysis, Yr29 and QYr.nwafu-4BL.3 were identified as genetic components of quantitative resistance in a number of wheat cultivars. Moreover, RILs with Yr29 and QYr.nwafu-4BL.3 individually or when combined showed higher resistance to YR in rust nurseries compared with RILs without them, and there was no negative effect of their presence on agronomic traits under rust-free conditions. These results suggest that effective polymerization strategy is important for breeding high yielding and durable resistance cultivars. [ABSTRACT FROM AUTHOR]

Key message: Mutations in TaCHLI impact chlorophyll levels and yield-related traits in wheat. Natural variations in TaCHLI-7A/B influence plant productivity, offering potential for molecular breeding. Chlorophyll is essential for plant growth and productivity. The CHLI subunit of the magnesium chelatase protein plays a key role inserting magnesium into protoporphyrin IX during chlorophyll biosynthesis. Here, we identify a novel wheat mutant chlorophyll (chl) that exhibits yellow-green leaves, reduced chlorophyll levels, and increased carotenoid content, leading to an overall decline in yield-related traits. Map-based cloning reveals that the chl phenotype is caused by a point mutation (Asp186Asn) in the TaCHLI-7D gene, which encodes subunit I of magnesium chelatase. Furthermore, the three TaCHLI mutants: chl-7b-1 (Pro82Ser), chl-7b-2 (Ala291Thr), and chl-7d-1 (Gly357Glu), also showed significant reductions in chlorophyll content and yield-related traits. However, TaCHLI-7D overexpression in rice significantly decreased thousand kernel weight, yield per plant, and germination. Additionally, natural variations in TaCHLI-7A/B are significantly associated with flag leaf, spike exsertion length, and yield per plant. Notably, the favorable haplotype, TaCHLI-7B-HapII, which displayed higher thousand kernel weight and yield per plant, is positively selected in wheat breeding. Our study provides insights on the regulatory molecular mechanisms underpinning leaf color and chlorophyll biosynthesis, and highlights TaCHLI functions, which provide useful molecular markers and genetic resources for wheat breeding. [ABSTRACT FROM AUTHOR]

Key message: Identification of 337 stable MTAs for wheat spike-related traits improved model accuracy, and favorable alleles of MTA259 and MTA64 increased grain weight and yield per plant. Wheat (Triticum aestivum L.) is one of the three primary global, staple crops. Improving spike-related traits in wheat is crucial for optimizing spike and plant morphology, ultimately leading to increased grain yield. Here, we performed a genome-wide association study using a dataset of 24,889 high-quality unique single-nucleotide polymorphisms (SNPs) and phenotypic data from 314 wheat accessions across eight diverse environments. In total, 337 stable and significant marker–trait associations (MTAs) related to spike-related traits were identified. MTA259 and MTA64 were consistently detected in seven and six environments, respectively. The presence of favorable alleles associated with MTA259 and MTA64 significantly reduced wheat spike exsertion length and spike length, while enhancing thousand kernel weight and yield per plant. Combined gene expression and network analyses identified TraesCS6D03G0692300 and TraesCS6D03G0692700 as candidate genes for MTA259 and TraesCS2D03G0111700 and TraesCS2D03G0112500 for MTA64. The identified MTAs significantly improved the prediction accuracy of each model compared with using all the SNPs, and the random forest model was optimal for genome selection. Additionally, the eight stable and major MTAs, including MTA259, MTA64, MTA66, MTA94, MTA110, MTA165, MTA180, and MTA164, were converted into cost-effective and efficient detection markers. This study provided valuable genetic resources and reliable molecular markers for wheat breeding programs. [ABSTRACT FROM AUTHOR]

Spike length (SL) is one of the most important agronomic traits affecting yield potential and stability in wheat. In this study, a major stable quantitative trait locus (QTL) for SL, i.e., qSl-2B, was detected in multiple environments in a recombinant inbred line (RIL) mapping population, KJ-RILs, derived from a cross between Kenong 9204 (KN9204) and Jing 411 (J411). The qSl-2B QTL was mapped to the 60.06–73.06 Mb region on chromosome 2B and could be identified in multiple mapping populations. An InDel molecular marker in the target region was developed based on a sequence analysis of the two parents. To further clarify the breeding use potential of qSl-2B, we analyzed its genetic effects and breeding selection effect using both the KJ-RIL population and a natural mapping population, which consisted of 316 breeding varieties/advanced lines. The results showed that the qSl-2B alleles from KN9204 showed inconsistent genetic effects on SL in the two mapping populations. Moreover, in the KJ-RILs population, the additive effects analysis of qSl-2B showed that additive effect was higher when both qSl-2D and qSl-5A harbor negative alleles under LN and HN. In China, a moderate selection utilization rate for qSl-2B was found in the Huanghuai winter wheat area and the selective utilization rate for qSl-2B continues to increase. The above findings provided a foundation for the genetic improvement of wheat SL in the future via molecular breeding strategies. Key message: A major stable QTL for spike length was identified in wheat, and its genetic effect on yield related-traits as well as its potential use value in molecular breeding programs were characterized. [ABSTRACT FROM AUTHOR]

Key message: A total of 38 putative additive QTLs and 55 pairwise putative epistatic QTLs for tiller-related traits were reported, and the candidate genes underlying qMtn-KJ-5D, a novel major and stable QTL for maximum tiller number, were characterized. Tiller-related traits play an important role in determining the yield potential of wheat. Therefore, it is important to elucidate the genetic basis for tiller number when attempting to use genetic improvement as a tool for enhancing wheat yields. In this study, a quantitative trait locus (QTL) analysis of three tiller-related traits was performed on the recombinant inbred lines (RILs) of a mapping population, referred to as KJ-RILs, that was derived from a cross between the Kenong 9204 (KN9204) and Jing 411 (J411) lines. A total of 38 putative additive QTLs and 55 pairwise putative epistatic QTLs for spike number per plant (SNPP), maximum tiller number (MTN), and ear-bearing tiller rate (EBTR) were detected in eight different environments. Among these QTLs with additive effects, three major and stable QTLs were first documented herein. Almost all but two pairwise epistatic QTLs showed minor interaction effects accounting for no more than 3.0% of the phenotypic variance. The genetic effects of two colocated major and stable QTLs, i.e., qSnpp-KJ-5D.1 and qMtn-KJ-5D, for yield-related traits were characterized. The breeding selection effect of the beneficial allele for the two QTLs was characterized, and its genetic effects on yield-related traits were evaluated. The candidate genes underlying qMtn-KJ-5D were predicted based on multi-omics data, and TraesKN5D01HG00080 was identified as a likely candidate gene. Overall, our results will help elucidate the genetic architecture of tiller-related traits and can be used to develop novel wheat varieties with high yields. [ABSTRACT FROM AUTHOR]

Key message: A major stable QTL, qKl-1BL, for kernel length of wheat was narrowed down to a 2.04-Mb interval on chromosome 1BL; the candidate genes were predicated and the genetic effects on yield-related traits were characterized. As a key factor influencing kernel weight, wheat kernel shape is closely related to yield formation, and in turn affects both wheat processing quality and market value. Fine mapping of the major quantitative trait loci (QTL) for kernel shape could provide genetic resources and a theoretical basis for the genetic improvement of wheat yield-related traits. In this study, a major QTL for kernel length (KL) on 1BL, named qKl-1BL, was identified from the recombinant inbred lines (RIL) in multiple environments based on the genetic map and physical map, with 4.76–21.15% of the phenotypic variation explained. To fine map qKl-1BL, the map-based cloning strategy was used. By using developed InDel markers, the near-isogenic line (NIL) pairs and eight key recombinants were identified from a segregating population containing 3621 individuals derived from residual heterozygous lines (RHLs) self-crossing. In combination with phenotype identification, qKl-1BL was finely positioned into a 2.04-Mb interval, KN1B:698.15–700.19 Mb, with eight differentially expressed genes enriched at the key period of kernel elongation. Based on transcriptome analysis and functional annotation information, two candidate genes for qKl-1BL controlling kernel elongation were identified. Additionally, genetic effect analysis showed that the superior allele of qKl-1BL from Jing411 could increase KL, thousand kernel weight (TKW), and yield per plant (YPP) significantly, as well as kernel bulk density and stability time. Taken together, this study identified a QTL interval for controlling kernel length with two possible candidate genes, which provides an important basis for qKl-1BL cloning, functional analysis, and application in molecular breeding programs. [ABSTRACT FROM AUTHOR]

Key message: A major stable QTL for kernel number per spike was narrowed down to a 2.19-Mb region containing two potential candidate genes, and its effects on yield-related traits were characterized. Kernel number per spike (KNPS) in wheat is a key yield component. Dissection and characterization of major stable quantitative trait loci (QTLs) for KNPS would be of considerable value for the genetic improvement of yield potential using molecular breeding technology. We had previously reported a major stable QTL controlling KNPS, qKnps-4A. In the current study, primary fine-mapping analysis, based on the primary mapping population, located qKnps-4A to an interval of approximately 6.8-Mb from 649.0 to 655.8 Mb on chromosome 4A refering to ‘Kenong 9204’ genome. Further fine-mapping analysis based on a secondary mapping population narrowed qKnps-4A to an approximately 2.19-Mb interval from 653.72 to 655.91 Mb. Transcriptome sequencing, gene function annotation analysis and homologous gene related reports showed that TraesKN4A01HG38570 and TraesKN4A01HG38590 were most likely to be candidate genes of qKnps-4A. Phenotypic analysis based on paired near-isogenic lines in the target region showed that qKnps-4A increased KNPS mainly by increasing the number of central florets per spike. We also evaluated the effects of qKnps-4A on other yield-related traits. Moreover, we dissected the QTL cluster of qKnps-4A and qTkw-4A and proved that the phenotypic effects were probably due to close linkage of two or more genes rather than pleiotropic effects of a single gene. This study provides molecular marker resource for wheat molecular breeding designed to improve yield potential, and lay the foundation for gene functional analysis of qKnps-4A. [ABSTRACT FROM AUTHOR]

Key message: The temporal and spatial expression patterns of stable QTL for plant height and their influences on yield were characterized. Abstract: Plant height (PH) is a complex trait in wheat ( Triticum aestivum L.) that includes the spike length (SL) and the internode lengths from the first to the fifth internode, which are counted from the top and abbreviated as FIRITL, SECITL, THIITL, FOUITL, and FIFITL, respectively. This study identified eight putative additive quantitative trait loci (QTL) for PH. In addition, unconditional and conditional QTL mapping were used to analyze the temporal and spatial expression patterns of five stable QTL for PH. qPh-3A mainly regulated SL, FIRITL, and FIFITL to affect PH during the booting-heading stage (BS-HS); qPh-3D regulated all internode lengths to affect PH, especially during the BS-HS; before HS, qPh-4B mainly affected FIRITL, SECITL, THIITL, and FOUITL and qPh-5A.1 mainly affected SECITL, THIITL, and FOUITL to regulate PH; and qPh-6B mainly regulated FIRITL to affect the PH after the booting stage (BS). qPhdv-4B, a QTL for the response of PH to nitrogen stress, was stable and co-localized with qPh-4B. All five stable QTL, except for qPh-3A, were related to the 1000 kernel weight and yield per plant. Regions of qPh-3A, qPh-3D, qPh-4B, qPh-5A.1, and qPh-6B showed synteny to parts of rice chromosomes 1, 1, 3, 9, and 2, respectively. Based on comparative genomics analysis, Rht-B1b was cloned and mapped in the CI of qPh-4B. This report provides useful information for fine mapping of the stable QTL for PH and the genetic improvement of wheat plant type. [ABSTRACT FROM AUTHOR]

Plant height (PH) is one of the most important traits related to plant architecture in wheat. Together, the lengths of individual internodes determine plant height and have a great influence on lodging resistance. To specify the genetic basis of wheat internode characteristics, we identified quantitative trait loci (QTLs) for each internode component index (ICI) and plant height component index (PHCI) using a recombinant inbred line (RIL) mapping population derived from 'Kenong 9204' ('KN9204') × 'Jing 411' ('J411'). Up to 57 putative additive QTLs for the four ICIs and PHCI were detected, which together covered 20 of the 21 wheat chromosomes, with the exception of chromosome 1B. Among them, eight QTLs were major, stable QTLs with a logarithm-of-odds (LOD) score of ≥ 3.0 and a phenotypic variance explained (PVE) of ≥ 7.0%. In the epistatic analysis, only one pair of epistatic QTLs was identified for the first internode component index (FIITCI) and three pairs of epistatic QTLs for the third internode component index (TITCI). A total of 20 of the 57 detected QTLs (35.1%) were co-localized QTLs for PH, spike length, and internode lengths, indicating that those traits have their own individual genetic basis in most cases. Moreover, 12 QTL clusters for PHCI/ICIs and yield-related traits were identified, indicating that plant architecture plays a potential role in the formation of yield in wheat. The plant architecture with gradually bottom-up shortened internode lengths tends to be high-yielding potential, especially for the uppermost internode. This study may provide useful information for understanding the genetic basis of plant height components and to accelerate the genetic improvement of plant ideotypes designed to increase yield. [ABSTRACT FROM AUTHOR]

Melatonin (Mel) is a multifunctional biomolecule found in both animals and plants. In plants, the biosynthesis of Mel from tryptophan (Trp) has been delineated to comprise of four consecutive reactions. However, while the genes encoding these enzymes in rice are well characterized no systematic evaluation of the overall pathway has, as yet, been published for wheat. In the current study, the relative contents of six Mel‐pathway‐intermediates including Trp, tryptamine (Trm), serotonin (Ser), 5‐methoxy tryptamine (5M‐Trm), N‐acetyl serotonin (NAS) and Mel, were determined in 24 independent tissues spanning the lifetime of wheat. These studies indicated that Trp was the most abundant among the six metabolites, followed by Trm and Ser. Next, the candidate genes expressing key enzymes involved in the Mel pathway were explored by means of metabolite‐based genome‐wide association study (mGWAS), wherein two TDC genes, a T5H gene and one SNAT gene were identified as being important for the accumulation of Mel pathway metabolites. Moreover, a 463‐bp insertion within the T5H gene was discovered that may be responsible for variation in Ser content. Finally, a ASMT gene was found via sequence alignment against its rice homolog. Validations of these candidate genes were performed by in vitro enzymatic reactions using proteins purified following recombinant expression in Escherichia coli, transient gene expression in tobacco, and transgenic approaches in wheat. Our results thus provide the first comprehensive investigation into the Mel pathway metabolites, and a swift candidate gene identification via forward‐genetics strategies, in common wheat. [ABSTRACT FROM AUTHOR]

Key message: TaD11-2A affects grain size and root length and its natural variations are associated with significant differences in yield-related traits in wheat. Brassinosteroids (BRs) control many important agronomic traits and therefore the manipulation of BR components could improve crop productivity and performance. However, the potential effects of BR-related genes on yield-related traits and stress tolerance in wheat (Triticum aestivum L.) remain poorly understood. Here, we identified TaD11 genes in wheat (rice D11 orthologs) that encoded enzymes involved in BR biosynthesis. TaD11 genes were highly expressed in roots (Zadoks scale: Z11) and grains (Z75), while expression was significantly suppressed by exogenous BR (24-epiBL). Ectopic expression of TaD11-2A rescued the abnormal panicle structure and plant height (PH) of the clustered primary branch 1 (cpb1) mutant, and also increased endogenous BR levels, resulting in improved grain yields and grain quality in rice. The tad11-2a-1 mutant displayed dwarfism, smaller grains, sensitivity to 24-epiBL, and reduced endogenous BR contents. Natural variations in TaD11-2A were associated with significant differences in yield-related traits, including PH, grain width, 1000-grain weight, and grain yield per plant, and its favorable haplotype, TaD11-2A-HapI was subjected to positive selection during wheat breeding. Additionally, TaD11-2A influenced root length and salt tolerance in rice and wheat at seedling stages. These results indicated the important role of BR TaD11 biosynthetic genes in controlling grain size and root length, and also highlighted their potential in the molecular biological analysis of wheat. [ABSTRACT FROM AUTHOR]

As one of the important spike components, spikelet number is closely related to wheat yield. In the present study, a major stable QTL for spikelet number per spike (SNPS), qSnps-7D, was identified using a recombinant inbred line mapping population derived from the cross between Kenong 9204 (KN9204) and Jing 411 (J411) (KJ-RILs). To decipher its genetic effects on yield-related traits and selection effects in wheat breeding process, phenotype data together with genotype data from KJ-RILs and a natural mapping population were collected. qSnps-7D was mapped to the interval of 1.63 Mb on chromosome 7D in the KN9204 genome assembly in 4 of the 6 datasets. The favored alleles from KN9204 could significantly increase SNPS, kernel number per spike (KNPS). The diagnostic markers for SNPS were further developed and validated. The selection utilization rate of the favored haplotype in foreign varieties was lower than that in China, and it showed an increasing trend with time passage, with the ratio reaching more than 50% since the 1990s. In addition, loci for yield-related traits co-located with qSnps-7D were sorted out. Meanwhile, the relationship between SNPS and its components as well as other important yield-related traits were also discussed. Taken together, the studies will lay foundation for gene cloning and molecular breeding utilization of qSnps-7D. [ABSTRACT FROM AUTHOR]

Key message: A major stable QTL for flag leaf width was narrowed down to 2.5 Mb region containing two predicated putative candidate genes, and its effects on yield-related traits was characterized. Flag leaf width (FLW) is important to production in wheat. In a previous study, a major quantitative trait locus for FLW (QFlw-5B) was detected on chromosome 5B, within an interval of 6.5 cM flanked by the markers of XwPt-9103 and Xbarc142, using a mapping population of recombinant inbred lines derived from a cross between Kenong9204 (KN9204) and Jing411 (J411) (denoted as KJ-RILs). The aim of this study was to fine map QFlw-5B and characterize its genetic effects on yield-related traits. Multiple near-isogenic lines (NILs) were developed using one residual heterozygous line for QFlw-5B. Five recombinants for QFlw-5B were identified, and its location was narrowed to a 2.5 Mb region based on combined phenotypic and genotypic data analysis. This region contained 27 predicted genes, two of which were considered as the most likely candidate genes for QFlw-5B. The FLW of NIL-KN9204 was significantly higher than that of NIL-J411 across all the tested environments. Meanwhile, significant increases in plant height, grain width and 1000-grain weight were observed in NIL-KN9204 compared with that in NIL-J411. These results indicate that QFlw-5B has great potential for marker-assisted selection in wheat breeding programs designed to improve both plant architecture and yield. This study also provides a basis for the map-based cloning of QFlw-5B. [ABSTRACT FROM AUTHOR]

Brassinosteroids (BRs) are a group of plant steroid hormones that regulate many important agronomic traits. Studies on the functional mechanisms of BR-related genes in crop plants are necessary for the application of BRs in agriculture. In this study, ZmD11 , an ortholog of rice DWARF11 (D11), and 42 other BR biosynthesis-related genes were identified in maize (Zea mays). Complementary experiments confirmed that ZmD11 completely rescued the abnormal panicle architecture and plant height of the rice cpb1 mutant. A phylogenetic analysis indicated that ZmD11-like proteins were found in other monocots and dicots, but not in lower plants and that alternative splicing variants of these homologues mainly exist in Triticeae crops. A subcellular localization analysis showed that ZmD11 localized to the endoplasmic reticulum. The ZmD11 gene was predominantly expressed in young ears and seeds from 10 to 16 days after pollination, especially in the scutellar aleurone layer and pericarp. Furthermore, the constitutive expression of the ZmD11 gene significantly increased seed length, seed area, seed weight and both seed starch and protein contents in rice and maize. Our results suggest that ZmD11 is a key gene in the regulation of seed size and quality and that it has a potential application value in the molecular breeding of crops. • ZmD11 and 42 other BR biosynthesis-related genes were identified in maize. • ZmD11 could rescue the abnormal panicle architecture and plant height of the rice cpb1 mutant. • Overexpression of ZmD11 significantly increased seed size and quality in rice and maize. [ABSTRACT FROM AUTHOR]

Summary: Plants produce numerous metabolites that are important for their development and growth. However, the genetic architecture of the wheat metabolome has not been well studied. Here, utilizing a high‐density genetic map, we conducted a comprehensive metabolome study via widely targeted LC‐MS/MS to analyze the wheat kernel metabolism. We further combined agronomic traits and dissected the genetic relationship between metabolites and agronomic traits. In total, 1260 metabolic features were detected. Using linkage analysis, 1005 metabolic quantitative trait loci (mQTLs) were found distributed unevenly across the genome. Twenty‐four candidate genes were found to modulate the levels of different metabolites, of which two were functionally annotated by in vitro analysis to be involved in the synthesis and modification of flavonoids. Combining the correlation analysis of metabolite‐agronomic traits with the co‐localization of methylation quantitative trait locus (mQTL) and phenotypic QTL (pQTL), genetic relationships between the metabolites and agronomic traits were uncovered. For example, a candidate was identified using correlation and co‐localization analysis that may manage auxin accumulation, thereby affecting number of grains per spike (NGPS). Furthermore, metabolomics data were used to predict the performance of wheat agronomic traits, with metabolites being found that provide strong predictive power for NGPS and plant height. This study used metabolomics and association analysis to better understand the genetic basis of the wheat metabolism which will ultimately assist in wheat breeding. Significance Statement: This work performed a comprehensive metabolome analysis of kernels from wheat RILs, which, in conjunction with wheat genome data, provided a valuable resource for mQTL analysis, identification of unknown enzymes, and metabolite‐agronomic trait correlations. [ABSTRACT FROM AUTHOR]

Key message: QTL for a wheat ideotype root system and its plasticity to nitrogen deficiency were characterized.Abstract: Root system architecture-related traits (RRTs) and their plasticity to nitrogen availability are important for nitrogen acquisition and yield formation in wheat (Triticum aestivum L.). In this study, quantitative trait loci (QTL) analysis was conducted under different nitrogen conditions, using the seedlings of 188 recombinant inbred lines derived from a cross between Kenong 9204 and Jing 411. Fifty-three QTL for seven RRTs and fourteen QTL for the plasticity of these RRTs to nitrogen deficiency were detected. Thirty of these QTL were mapped in nine clusters on chromosomes 2B, 2D, 3A, 3D, 6B, 6D, 7A and 7B. Six of these nine clusters were also colocated with loci for nitrogen use efficiency (NUE)-related traits (NRTs). Among them, three QTL clusters (C2B, C6D and C7B) were highlighted, considering that they individually harbored three stable robust QTL (i.e., QMrl-2B.1, QdRs-6D and QMrl-7B). C2B and C7B stably contributed to the optimal root system, and C6D greatly affected the plasticity of RRTs in response to nitrogen deficiency. However, strong artificial selection was only observed for C7B in 574 derivatives of Kenong 9204. Covariance analysis identified QMrl-7B as the major contributor in C7B that affected the investigated NRTs in mature plants. Phenotypic analysis indicated that thousand kernel weight might represent a “concomitant” above-ground trait of the “hidden” RRTs controlled by C7B, which are used for breeding selection. Dissecting these QTL regions with potential breeding value will ultimately facilitate the selection of donor lines with both high yield and NUE in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Nicotianamine synthase (NAS) plays a pivotal role in balancing the concentrations of heavy metals in plants, but its characteristics and functions in salt stress responses are not completely understood, particularly in wheat. In this study, the salt-induced gene TaNAS-D was cloned from wheat and characterized. TaNAS-D, localized throughout the cell, is mainly expressed in developed vascular bundle tissues and is responsive to NaCl, ABA, and HO stresses. Overexpression of TaNAS-D in Arabidopsis led to elevated NA levels and enhanced salt stress tolerance, which was demonstrated by higher germination rates and improved growth of TaNAS-D transgenic Arabidopsis plants compared with WT when exposed to salt stress. Further investigation revealed that TaNAS-D transgenic Arabidopsis plants displayed higher K/Na ratios, lower malondialdehyde (MDA) levels, and less ion leakage (IL) consistently accompanied by increased peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities, thereby reducing membrane injury. Moreover, TaNAS-D overexpression under salt stress increased AtSOS1, AtSOS2, AtSOS3, AtFAD5, and AtSAD1 transcript levels. These findings indicate that TaNAS-D plays a positive role in salt tolerance by improving the antioxidant defense system and upregulating salt overly sensitive (SOS) pathway genes. [ABSTRACT FROM AUTHOR]

Introduction: Acrolein (2-propenal) is a reactive α, β-unsaturated aldehyde which causes a health hazard to humans. The present study focused on determining the protection offered by sulforaphane against acrolein-induced damage in peripheral blood mononuclear cells (PBMC).Material and Methods: Acrolein-induced oxidative stress was determined through evaluating the levels of reactive oxygen species, protein carbonyl and sulfhydryl content, thiobarbituric acid reactive species, total oxidant status and antioxidant status (total antioxidant capacity, glutathione, superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase activity). Also, Nrf-2 expression levels were determined using western blot analysis. Acrolein-induced inflammation was determined through analyzing expression of cyclooxygenase-2 by western blot and PGE2 levels by ELISA. The protection offered by sulforaphane against acrolein-induced oxidative stress and inflammation was studied.Results: Acrolein showed a significant (p < 0.001) increase in the levels of oxidative stress parameters and down-regulated Nrf-2 expression. Acrolein-induced inflammation was observed through upregulation (p < 0.001) of COX-2 and PGE2 levels. Pretreatment with sulforaphane enhanced the antioxidant status through upregulating Nrf-2 expression (p < 0.001) in PBMC. Acrolein-induced inflammation was significantly inhibited through suppression of COX-2 (p < 0.001) and PGE2 levels (p < 0.001).Conclusions: The present study provides clear evidence that pre-treatment with sulforaphane completely restored the antioxidant status and prevented inflammatory responses mediated by acrolein. Thus the protection offered by sulforaphane against acrolein-induced damage in PBMC is attributed to its anti-oxidant and anti-inflammatory potential. [ABSTRACT FROM AUTHOR]

Background: Common wheat (Triticum aestivum L.) is one of the most important food crops worldwide. Wheat spike-layer uniformity related traits (SLURTs) were complex traits that directly affect yield potential and appearance. In this study, quantitative trait locus (QTL) for five SLURTs among inter-tillers were first documented using a recombinant inbred line (RIL) mapping population derived from a cross between Kenong9204 and Jing411 (represented by KJ-RILs). Genetic relationships between SLURTs and yield were characterized in detail. Results: The trait phenotypic performances for the 188 KJ-RILs and their parents were evaluated in eight different environments. The genetic data included in a high-density genetic map derived from the Affymetrix 660 K SNP Array and the corresponding genotypes in each lines. Of 99 putative additive QTL 11 were stable across environments and 57 showed significant additive-by-environment interaction effects. These QTL individually explained 1.05–39.62% of the phenotypic variance, with log of odds (LOD) values ranging from 2.00 to 34.01. Genetic relationships between SLURTs and yield indicated that plants with slight uneven spike spatial distribution should be an ideotype for super high-yield in wheat. Conclusions: The present study will provide assistance in understanding the genetic relationships between SLURTs and yield potential. The 11 stable QTL for SLURTs identified herein may facilitate breeding new wheat varieties with scientifically reasonable spike-layer distribution by marker assisted selection. [ABSTRACT FROM AUTHOR]

Flag leaf-related traits (FLRTs) are determinant traits affecting plant architecture and yield potential in wheat (Triticum aestivum L.). In this study, three related recombinant inbred line (RIL) populations with a common female parent were developed to identify quantitative trait loci (QTL) for flag leaf width (FLW), length (FLL), and area (FLA) in four environments. A total of 31 QTL were detected in four environments. Two QTL for FLL on chromosomes 3B and 4A (QFll-3B and QFll-4A) and one for FLW on chromosome 2A (QFlw-2A) were major stable QTL. Ten QTL clusters (C1-C10) simultaneously controlling FLRTs and yield-related traits (YRTs) were identified. To investigate the genetic relationship between FLRTs and YRTs, correlation analysis was conducted. FLRTs were found to be positively correlated with YRTs especially with kernel weight per spike and kernel number per spike in all the three RIL populations and negatively correlated with spike number per plant. Appropriate flag leaf size could benefit the formation of high yield potential. This study laid a genetic foundation for improving yield potential in wheat molecular breeding programs. [ABSTRACT FROM AUTHOR]

Plastic glutamine synthetase (GS2) is responsible for ammonium assimilation. The reason that TaGS2 homoeologs in hexaploid wheat experience different selection pressures in the breeding process remains unclear. TaGS2 were minimally expressed in roots but predominantly expressed in leaves, and TaGS2-B had higher expression than TaGS2-A and TaGS2-D. ChIP assays revealed that the activation of TaGS2-B expression in leaves was correlated with increased H3K4 trimethylation. The transcriptional silencing of TaGS2 in roots was correlated with greater cytosine methylation and less H3K4 trimethylation. Micrococcal nuclease and DNase I accessibility experiments indicated that the promoter region was more resistant to digestion in roots than leaves, which indicated that the closed nucleosome conformation of the promoter region was important to the transcription initiation for the spatial-temporal expression of TaGS2. In contrast, the transcribed regions possess different nuclease accessibilities of three TaGS2 homoeologs in the same tissue, suggesting that nucleosome conformation of the transcribed region was part of the fine adjustment of TaGS2 homoeologs. This study provides evidence that histone modification, DNA methylation and nuclease accessibility coordinated the control of the transcription of TaGS2 homoeologs. Our results provided important evidence that TaGS2-B experienced the strongest selection pressures during the breeding process. [ABSTRACT FROM AUTHOR]