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A co-located KL and TKW-related QTL with no negative effect on PH and AD was rapidly identified using BSA and wheat 660 K SNP array. Its effect was validated in a panel of 218 wheat accessions. Kernel length (KL) and thousand-kernel weight (TKW) of wheat (Triticum aestivum L.) contribute significantly to kernel yield. In the present study, a recombinant inbred line (RIL) population derived from the cross between the wheat line S849-8 with larger kernels and more spikelets per spike and the line SY95-71 was developed. Further, of both the bulked segregant analysis (BSA) and the wheat 660 K single nucleotide polymorphism (SNP) array were used to rapidly identify genomic regions for kernel-related traits from this RIL population. Kompetitive Allele Specific PCR markers were further developed in the SNP-enriched region on the 2D chromosome to construct a genetic map. Both QKL.sicau-SSY-2D for KL and QTKW.sicau-SSY-2D for TKW were identified at multiple environments on chromosome arm 2DL. These two QTLs explained 9.68-23.02% and 6.73-18.32% of the phenotypic variation, respectively. The effects of this co-located QTL were successfully verified in a natural population consisting of 218 Sichuan wheat accessions. Interestingly, the major QTL was significantly and positively correlated with spike length, but did not negatively affect spikelet number per spike (SNS), plant height, or anthesis date. These results indicated that it is possible to synchronously improve kernel weight and SNS by using this QTL. Additionally, several genes associated with kernel development and filling rate were predicted and sequenced in the QTL-containing physical intervals of reference genomes of 'Chinese spring' and Aegilops tauschii. Collectively, these results provide a QTL with great breeding potential and its linked markers which should be helpful for fine mapping and molecular breeding.

Background Fusarium crown rot (FCR) is a chronic disease of cereals worldwide. Compared with tetraploid wheat, hexaploid wheat is more resistant to FCR infection, but little is known about the contributions of allohexaploidization to wheat FCR resistance. In this study, we compared FCR responses of 10 synthetic hexaploid wheats (SHWs) and their tetraploid and diploid parents and then further analyzed transcriptome data from two SHWs and their parents. Results We observed that stronger FCR resistance emerged immediately in the SHWs following allohexaploidization. The transcriptome analysis suggested that multiple defense pathways responsive to FCR infection were stronger in the SHWs than in the parents. In particular, dozens of phenylalanine ammonia lyase (PAL) genes, involved in lignin and salicylic acid (SA) biosynthesis, exhibited a higher degree of response to FCR infection in the SHWs. Physiological measurements later confirmed that PAL activities and SA and lignin contents of the stem bases of the SHWs were higher than those of the tetraploid parents. Conclusion Overall, these findings imply that the stronger FCR resistance of hexaploid wheat compared with tetraploid wheat is probably due to changes in PAL-mediated lignin and SA biosynthesis pathways after allohexaploidization.

Chinese wheat landrace Anyuehong (AYH) has displayed high levels of stable adult plant resistance (APR) to stripe rust for >15 years. To identify quantitative trait loci (QTLs) for stripe rust resistance in AYH, a set of 110 recombinant inbred lines (RILs) was developed from a cross between AYH and susceptible cultivar Taichung 29. The parents and RILs were evaluated for final disease severity (FDS) in six field tests with a mixture of predominant Puccinia striiformis f. sp. tritici races at the adult plant stage and genotyped via the wheat 55K single-nucleotide polymorphism (SNP) array to construct a genetic map with 1,143 SNP markers. Three QTLs, designated as QYr.AYH-1AS, QYr.AYH-5BL, and QYr.AYH-7DS, were mapped on chromosome 1AS, 5BL, and 7DS, respectively. RILs combining three QTLs showed significantly lower FDS compared with the lines in other combinations. Of them, QYr.AYH-5BL and QYr.AYH-7DS were stably detected in all environments, explaining 13.6 to 21.4% and 17.6 to 33.6% of phenotypic variation, respectively. Compared with previous studies, QYr.AYH-5BL may be a new QTL, whereas QYr.AYH-7DS may be Yr18. Haplotype analysis revealed that QYr.AYH-5BL is probably present in 6.2% of the 323 surveyed Chinese wheat landraces. The kompetitive allele specific PCR (KASP) markers for QYr.AYH-5BL were developed by the linked SNP markers to successfully confirm the effects of the QTL in a validation population derived from a residual heterozygous line and were further assessed in 38 Chinese wheat landraces and 92 cultivars. Our results indicated that QYr.AYH-5BL with linked KASP markers has potential value for marker-assisted selection to improve stripe rust resistance in breeding programs.

Summary Pre‐harvest sprouting (PHS), the germination of grain before harvest, is a serious problem resulting in wheat yield and quality losses.Here, we mapped the PHS resistance gene PHS‐3D from synthetic hexaploid wheat to a 2.4 Mb presence–absence variation (PAV) region and found that its resistance effect was attributed to the pleiotropic Myb10‐D by integrated omics and functional analyses.Three haplotypes were detected in this PAV region among 262 worldwide wheat lines and 16 Aegilops tauschii, and the germination percentages of wheat lines containing Myb10‐D was approximately 40% lower than that of the other lines. Transcriptome and metabolome profiling indicated that Myb10‐D affected the transcription of genes in both the flavonoid and abscisic acid (ABA) biosynthesis pathways, which resulted in increases in flavonoids and ABA in transgenic wheat lines. Myb10‐D activates 9‐cis‐epoxycarotenoid dioxygenase (NCED) by biding the secondary wall MYB‐responsive element (SMRE) to promote ABA biosynthesis in early wheat seed development stages.We revealed that the newly discovered function of Myb10‐D confers PHS resistance by enhancing ABA biosynthesis to delay germination in wheat. The PAV harboring Myb10‐D associated with grain color and PHS will be useful for understanding and selecting white grained PHS resistant wheat cultivars.

In this study, we investigated the starch properties of Aegilops sharonensis (R7), tetraploid wheat (Z636), and their amphidiploid (Z636 × R7). The results of protein electrophoresis showed that waxy protein of Ae. sharonensis (R7) and tetraploid wheat (Z636) is expressed in the amphidiploid (Z636 × R7). The total starch content and amylose content of the amphidiploid (Z636 × R7) were higher than Ae. sharonensis (R7) and lower than tetraploid wheat (Z636). The amphidiploid (Z636 × R7) exhibits an intermediate type of starch granules morphology that the ratio of A/B-type starch granules and their shapes ranged between Ae. sharonensis and tetraploid wheat. The gelatinization parameters showed that the concluding temperature (Tc) and enthalpy change (ΔH) of Ae. sharonensis (R7) were significantly lower than those of tetraploid wheat (Z636) and the amphidiploid (Z636 × R7), while the values of onset temperature (To) and peak temperature (Tp) were similar among the Ae. sharonensis (R7), tetraploid wheat (Z636), and the amphidiploid (Z636 × R7). For the aging properties, the ΔH values of Ae. sharonensis (R7) and the amphidiploid (Z636 × R7) were close but lower than that of tetraploid wheat (Z636), whereas the parameters of To, Tp, and Tc did not differ significantly among three materials. The amphidiploid (Z636 × R7) possesses varied starch properties from wheat, which may be useful in wheat quality improvement.

A novel, stably expressed, and plant height-independent QTL for spike extension length on 5AS was identified and validated in different populations using a newly developed and tightly linked KASP marker. As an important component of plant height (PH), spike extension length (SEL) plays a significant role in formation of an ideotype in wheat. Despite the fact that numerous loci for SEL in wheat have been reported, our knowledge on PH-independent loci remains to be limited. In this study, two recombinant inbred line (RIL) populations genotyped using the Wheat55K SNP were used to detect quantitative trait loci (QTL) controlling SEL across six environments. A total of 30 QTL for SEL were detected in these two RIL populations, and four of them, i.e., QSEL.sicau-2CN-4D, QSEL.sicau-2SY-4B.2, QSEL.sicau-2SY-4D.1, and QSEL.sicau-2CN-5A, were stably expressed. Genetic and conditional QTL analysis showed that the first three were significantly associated with PH, while the last one, QSEL.sicau-2CN-5A, is independent of PH. Comparison of genetic and physical maps suggested that only QSEL.sicau-2CN-5A located on chromosome arm 5AS is likely a novel QTL. A Kompetitive Allele-Specific PCR (KASP) marker, KASP-AX-110413733, tightly linked to this novel QTL was developed to successfully confirm its effect in three different genetic populations. Further, in the interval where QSEL.sicau-2CN-5A was located on 'Chinese Spring' wheat reference genome, three promising genes mainly expressed in wheat stem were predicated and they all encode the cytochrome P450 that was demonstrated to be closely associated with SEL elongation in rice. In addition, significant correlations between SEL and PH, spikelet number per spike, and thousand-grain weight were also detected. Altogether, our results broaden our understanding on genetic basis of SEL and will be useful for marker-based selection of lines with different SELs and fine mapping the novel and PH-independent QTL QSEL.sicau-2CN-5A.

Three EMS mutant wheat lines with varied mobility of Wx-A1 and Wx-B1 were identified. In the mutant lines M2-97-8 and M2-104-2, Wx-B1 showed slightly faster mobility compared to those of wild line, and Wx-A1 in the mutant line M2-101-1 has a greatly faster mobility, which co-migrates with Wx-D1. The results of gene sequencing indicated that SNP mutations appeared within exon of Wx-1 and further resulted in the mutation of amino acid residues in the mutant lines. The prediction analysis showed that the isoelectric point of the mutants M2-97-8 and M2-104-2 was more basic than that of the wild type while the isoelectric point of M2-101-1 was not changed; and the Waxy protein of the three mutations were all around 66 kDa. The SDS-PAGE results revealed that the mobility variation of Wx-B1 of M2-97-8 and M2-104-2 is due to the change of isoelectric point, while M2-101-1 may be caused by variation or modification of protein structure but not by the change of isoelectric point. The prokaryotic expression results further indicated that these mutated Wx-A1 and Wx-B1 genes migrated faster than those of wild Wx-A1 and Wx-B1 and were consistent with the results of molecular weight prediction. Although, the increased or decreased contents of total starch and amylose were observed in Wx-A1 or Wx-B1mutant, the correlation between the contents of total starch and amylose and the mutant Wx-A1 and Wx-B1 subunits cannot be determined. These mutants can not only increase the polymorphism of Waxy gene to investigate the function of these alleles, but also be valuable for wheat quality breeding.

In our previous work, a novel high-molecular-weight glutenin subunit (HMW-GS) with an extremely large molecular weight from Aegilops sharonensis was identified that may contribute to excellent wheat (Triticum aestivum) processing quality and increased dough strength, and we further generated HMW-GS homozygous lines by crossing. In this study, we crossed the HMW-GS homozygous line 66-17-52 with ‘Chinese Spring’ Ph1 mutant CS ph1b to induce chromosome recombination between wheat and Ae. sharonensis. SDS-PAGE was used to identify 19 derived F2 lines with the HMW-GSs of Ae sharonensis. The results of non-denaturing fluorescence in situ hybridization (ND-FISH) indicated that lines 6-1 and 6-7 possessed a substitution of both 5D chromosomes by a pair of 1Ssh chromosomes. Further verification by newly developed 1Ssh-specific chromosome markers showed that these two lines amplified the expected fragment. Thus, it was concluded that lines 6-1 and 6-7 are 1Ssh(5D) chromosome substitution lines. The 1Ssh(5D) chromosome substitution lines, possessing alien subunits with satisfactory quality-associated structural features of large repetitive domains and increased number of subunits, may have great potential in strengthening the viscosity and elasticity of dough made from wheat flour. Therefore, these substitution lines can be used for wheat quality improvement and further production of 1Ssh translocation lines.

Black point (BP) disease of wheat has become a noticeable problem in China. The symptoms are spots that are brown to black in color around the wheat kernel embryo or in the endosperm, resulting in a significant reduction of wheat grain quality. Here, we evaluated 272 Chinese wheat landraces for BP reaction and performed a genome-wide association study to identify BP resistance quantitative trait loci (QTLs) in five field environments without artificial inoculation. The BP incidence data showed continuous distributions and had low to moderate correlations between environments (r = 0.094 to 0.314). Among the 272 landraces, 11 had 0.1 to 4.9%, 144 had 5 to 14.9%, 100 had 15 to 29.9%, and 17 had >30% incidence. We found three resistant accessions: WH094 (3.33%), AS661463 (2.67%), and AS661231 (2.67%), which can be used in breeding programs to enhance BP resistance. We identified 11 QTLs, which explained 8.22 to 10.99% phenotypic BP variation, and mapped them to eight wheat chromosomes. Three of the QTLs were novel. The molecular markers for the BP resistance could facilitate molecular breeding for developing BP-resistant cultivars.

High yield and quality are essential goals of wheat (Triticum aestivum L.) breeding. Kernel length (KL), as a main component of kernel size, can indirectly change kernel weight and then affects yield. Identification and utilization of excellent loci in wheat genetic resources is of great significance for cultivating high yield and quality wheat. Genetic identification of loci for KL has been performed mainly through genome-wide association study in natural populations or QTL mapping based on genetic linkage map in high generation populations.In this study, an FA major, novel and stable QTL (Qkl.sicau-BLE18-4A) for KL was identified and verified in two F

Plant transcription factors (TFs), such as basic helix-loop-helix (bHLH) and AT-rich zinc-binding proteins (PLATZ), play critical roles in regulating the expression of developmental genes in cereals. We identified the bHLH protein TaPGS1 (T. aestivum Positive Regulator of Grain Size 1) specifically expressed in the seeds at 5-20 days post-anthesis in wheat. TaPGS1 was ectopically overexpressed (OE) in wheat and rice, leading to increased grain weight (up to 13.81% in wheat and 18.55% in rice lines) and grain size. Carbohydrate and total protein levels also increased. Scanning electron microscopy results indicated that the starch granules in the endosperm of TaPGS1 OE wheat and rice lines were smaller and tightly embedded in a proteinaceous matrix. Furthermore, TaPGS1 was bound directly to the E-box motif at the promoter of the PLATZ TF genes TaFl3 and OsFl3 and positively regulated their expression in wheat and rice. In rice, the OsFl3 CRISPR/Cas9 knockout lines showed reduced average thousand-grain weight, grain width, and grain length in rice. Our results reveal that TaPGS1 functions as a valuable trait-associated gene for improving cereal grain yield.

Wheat is a major staple food crop worldwide because of the unique properties of wheat flour. High molecular weight glutenin subunits (HMW-GSs), which are among the most critical determinants of wheat flour quality, are responsible for the formation of glutenin polymeric structures via interchain disulfide bonds. We herein describe the identification of a new HMW-GS Dy10 allele (Dy10-m619SN). The amino acid substitution (serine-to-asparagine) encoded in this allele resulted in a partial post-translational cleavage that produced two new peptides. These new peptides disrupted the interactions among gluten proteins because of the associated changes to the number of available cysteine residues for interchain disulfide bonds. Consequently, Dy10-m619SN expression decreased the size of glutenin polymers and weakened glutens, which resulted in wheat dough with improved cookie-making quality, without changes to the glutenin-to-gliadin ratio. In this study, we clarified the post-translational processing of HMW-GSs and revealed a new genetic resource useful for wheat breeding.

Chinese wheat landrace Anyuehong (AYH) has displayed high levels of stable adult plant resistance (APR) to stripe rust for15 years. To identify quantitative trait loci (QTLs) for stripe rust resistance in AYH, a set of 110 recombinant inbred lines (RILs) was developed from a cross between AYH and susceptible cultivar Taichung 29. The parents and RILs were evaluated for final disease severity (FDS) in six field tests with a mixture of predominant

Additional file 2. Pearson’s correlation coefficients for infection type (IT), final disease severity (FDS) and area under the disease progress curve (AUDPC) against stripe rust evaluated among five environments during 2016 to 2018. Different environments were all correlated, Significant at P

Additional file 4. Genome-wide average linkage disequilibrium (LD) decay plot for 143 wheat landraces based on 5899 DArT markers. The scatter plots showing pairwise DArT markers LD r2 value as a function of inter-marker genetic distances (cM).

Additional file 6. The avirulence(A) /virulence(V) formula of the Pst races used in this study.

Additional file 3. Population structure of 143 wheat landrace accessions in Southern Autumn-Sown Spring Wheat Zone of China. (a) The population structure of 143 accessions with Bayesian clustering analysis. Two colors stand for 2 different compositions. The Subgroup 1 (Gp1) mainly showed as red color. The Subgroup 2 (Gp2) mainly showed as green color; (b) Estimated the distance of hierarchical clustering for the accessions using Fast Ward grouping algorithm and heat map showing the kinship and phylogenetic relations.

Increasing wheat yield is essential in solving the global food shortage. The spikelet number per spike (SNS) is a primary factor that determines the kernel number per spike which has a great effect on wheat yield. Modern wheat breeding methods reduce the genetic diversity among cultivars, leading to a detrimental effect on future wheat production. It is, therefore, necessary to explore new genetic resources for SNS to increase wheat yield. A tetraploid landrace Ailanmai wild emmer wheat recombinant inbred line (RIL) population was used to construct a high-density genetic map using the wheat 55K single nucleotide polymorphism (SNP) array. The linkage map revealed that 94.83% (6204) of the mapped markers had consistent genetic and physical chromosomal locations. Fourteen quantitative trait loci (QTL) for SNS, explaining 4.23-27.26% of the phenotypic variation, were identified. QSns.sau-AM-2B.3 and QSns.sau-AM-3B.2 were detected as the major and novel QTL with a large cumulative effect that increased SNS by 17.47%. Some development-related genes within the physical intervals of QSns.sau-AM-2B.3 and QSns.sau-AM-3B.2 were predicted to participate in spikelet growth, thereby affecting SNS. Genetic associations between SNS and other agronomic traits such as a significant and positive correlation between SNS and thousand kernel weight (TKW) were detected and analyzed. QTL analysis was also performed for other spike-related traits, including spike length (SL), kernel number per spike (KNS), kernel number per spikelet (KNL), and spike density (SD). QSns.sau-AM-2B.3 was co-located with QSl.sau-AM-2B in the interval between AX-111626925 and AX-111588559. Similarly, QKns.sau-AM-5B.1 was co-related with QKnl.sau-AM-5B.2 in the region between AX-108760512 and AX-110180251. This study demonstrates the feasibility of wheat 55K SNP array in genetic mapping of tetraploid wheat population and shows the potential application of wheat related species in wheat improvement programs.

Backgrounds: Grain protein concentration (GPC), grain starch concentration (GSC), and wet gluten concentration (WGC) are complex traits that determine nutrient concentration, end-use quality, and yield in wheat. To identify the elite and stable loci or genomic regions conferring high GPC, GSC, and WGC, a genome-wide association study (GWAS) based on a mixed linear model (MLM) was performed using 55K single nucleotide polymorphism (SNP) array in a panel of 236 wheat accessions, including 160 commercial varieties and 76 landraces, derived from Sichuan Province, China. The panel was evaluated for GPC, GSC, and WGC at four different fields. Results: Phenotypic analysis showed variation in GPC, GSC, and WGC among the different genotypes and environments. GWAS identified 12 quantitative trait loci (QTL) (-log10(P) > 2.5) associated with these three quality traits in at least two environments and located on chromosomes 1B, 1D, 2A, 2B, 2D, 3B, 3D, 5D, and 7D; the phenotypic variation explained (PVE) by these QTL ranged from 4.2% to 10.7%. Among these, three, seven, and two QTL are associated with GPC, GSC, and WGC, respectively; five QTL (QGsc.sicau-1BL, QGsc.sicau-1DS, QGsc.sicau-2DL.1, QGsc.sicau-2DL.2, QWgc.sicau-5DL) were defined potentially novel Compared with the previously reported QTLs/genes by linkage or association mapping, 5 QTLs (QGsc.sicau-1BL, QGsc.sicau-1DS, QGsc.sicau-2DL.1, QGsc.sicau-2DL.2, QWgc.sicau-5DL) were potentially novel. Furthermore, 21 presumptive candidate genes, which are involved in the metabolism or transportation of all kinds of carbohydrates, photosynthesis, programmed cell death, the balance of abscisic acid and ethylene, within these potentially novel genomic regions were predicted. Conclusions: This study provided new genetic resources and valuable genetic information of nutritional quality to broaden the genetic background and laid the molecular foundation for marker-assisted selection in wheat quality breeding.

Stripe rust (yellow rust), caused by Puccinia striiformis f. sp. tritici, is one of the most destructive diseases of wheat worldwide. Chinese wheat landrace Guangtoumai (GTM) exhibited a high level of resistance against predominant P. striiformis f. sp. tritici races in China at the adult plant stage. The objective of this research was to identify and map the major locus/loci for stripe rust resistance in GTM. A set of 212 recombinant inbred lines (RILs) was developed from a cross between GTM and Avocet S. The parents and RILs were evaluated in three field tests (2018, 2019, and 2020 at Chongzhou, Sichuan) with the currently predominant P. striiformis f. sp. tritici races for final disease severity and genotyped with the Wheat 55K single nucleotide polymorphism (SNP) array to construct a genetic map with 1,031 SNP markers. A major locus, named QYr.GTM-5DL, was detected on chromosome 5DL in GTM. The locus was mapped in a 2.75-cM interval flanked by SNP markers AX-109855976 and AX-109453419, explaining up to 44.4% of the total phenotypic variation. Since no known Yr genes have been reported on chromosome 5DL, QYr.GTM-5DL is very likely a novel adult plant resistance locus. Haplotype analysis revealed that the resistance allele displayed enhanced levels of stripe rust resistance and is likely present in 5.3% of the 247 surveyed Chinese wheat landraces. The derived cleaved amplified polymorphic sequence (dCAPS) marker dCAPS-5722, converted from a SNP marker tightly linked to QYr.GTM-5DL with 0.3 cM, was validated on a subset of RILs and 48 commercial wheat cultivars developed in Sichuan. The results indicated that QYr.GTM-5DL with its linked dCAPS marker could be used in marker-assisted selection to improve stripe rust resistance in breeding programs, and this quantitative trait locus will provide new and possibly durable resistance to stripe rust.

Background Stripe rust, caused by the fungal pathogen Puccinia striiformis f. sp. tritici (Pst), is a serious foliar disease of wheat. Identification of novel stripe rust resistance genes and cultivation of resistant cultivars are considered to be the most effective approaches to control this disease. In this study, we evaluated the infection type (IT), disease severity (DS) and area under the disease progress curve (AUDPC) of 143 Chinese wheat landrace accessions for stripe rust resistance. Assessments were undertaken in five environments at the adult-plant stage with Pst mixture races under field conditions. In addition, IT was assessed at the seedling stage with two prevalent Pst races (CYR32 and CYR34) under a controlled greenhouse environment. Results Seventeen accessions showed stable high-level resistance to stripe rust across all environments in the field tests. Four accessions showed resistance to the Pst races CYR32 and CYR34 at the seedling stage. Combining phenotypic data from the field and greenhouse trials with 6404 markers that covered the entire genome, we detected 17 quantitative trait loci (QTL) on 11 chromosomes for IT associated with seedling resistance and 15 QTL on seven chromosomes for IT, final disease severity (FDS) or AUDPC associated with adult-plant resistance. Four stable QTL detected on four chromosomes, which explained 9.99–23.30% of the phenotypic variation, were simultaneously associated with seedling and adult-plant resistance. Integrating a linkage map of stripe rust resistance in wheat, 27 QTL overlapped with previously reported genes or QTL, whereas four and one QTL conferring seedling and adult-plant resistance, respectively, were mapped distantly from previously reported stripe rust resistance genes or QTL and thus may be novel resistance loci. Conclusions Our results provided an integrated overview of stripe rust resistance resources in a wheat landrace diversity panel from the southern autumn-sown spring wheat zone of China. The identified resistant accessions and resistance loci will be useful in the ongoing effort to develop new wheat cultivars with strong resistance to stripe rust.

Anthocyanins and selenium have vital biological functions for human and plants, they were investigated thoroughly and separately in plants. Previous studies indicated pigmented fruits and vegetables had higher selenium concentration, but whether there is a relationship between anthocyanins and selenium is unclear. In this study, a combined phenotypic and genotypic methodological approach was undertaken to explore the potential relationship between anthocyanins and selenium accumulation by using phenotypic investigation and RNA-seq analysis. The results showed that pigmented cultivars enrichment in Se is a general phenomenon observed for these tested species, this due to pigmented cultivars have higher Se efficiency absorption. Se flow direction mainly improve concentration of S-rich proteins of LMW-GS. This may be a result of the MYB and bHLH co-regulate anthocyanins biosynthesis and Se metabolism at the transcriptional level. This thesis addresses a neglected aspect of the relevant relationship between anthocyanins and selenium.

Eight major and stably expressed QTL for flag leaf morphology across eleven environments were identified and validated using newly developed KASP markers in seven biparental populations with different genetic backgrounds. Flag leaf morphology is a determinant trait influencing plant architecture and yield potential in wheat (Triticum aestivum L.). A recombinant inbred line (RIL) population with a 55 K SNP-based constructed genetic map was used to map quantitative trait loci (QTL) for flag leaf length (FLL), width (FLW), area (FLA), angle (FLANG), opening angle (FLOA), and bend angle (FLBA) in eleven environments. Eight major QTL were detected in 11 environments with 5.73–54.38% of explained phenotypic variation. These QTL were successfully verified using the newly developed Kompetitive Allele Specific PCR (KASP) markers in six biparental populations with different genetic backgrounds. Among these 8 major QTL, two co-located intervals were identified. Significant interactions for both FLL- and FLW-related QTL were detected. Comparison analysis showed that QFll.sau-SY-2B and QFla.sau-SY-2B are likely new loci. Significant relationships between flag leaf- and yield-related traits were observed and discussed. Several genes associated with leaf development including the ortholog of maize ZmRAVL1, a B3-domain transcription factor involved in regulation of leaf angle, were predicted in physical intervals harboring these major QTL on reference genomes of bread wheat ‘Chinese spring’, T. turgidum, and Aegilops tauschii. Taken together, these results broaden our understanding on genetic basis of flag leaf morphology and provide clues for fine mapping and marker-assisted breeding wheat with optimized plant architecture for promising loci.

Stripe rust caused by Puccinia striiformis f. sp. tritici (Pst) is one of the most devastating foliar diseases in wheat. Host resistance is the most effective strategy for the management of the disease. To screen for accessions with stable resistance and identify effective stripe rust resistance loci, a genome-wide association study (GWAS) was conducted using a panel of 140 Chinese wheat landraces. The panel was evaluated for stripe rust response at the adult-plant stage at six field-year environments with mixed races and at the seedling stage with two separate predominant races of the pathogen, and genotyped with the genome-wide Diversity Arrays Technology markers. The panel displayed abundant phenotypic variation in stripe rust responses, with 9 landraces showing stable resistance to the mixture of Pst races at the adult-plant stage in the field and 10 landraces showing resistance to individual races at the seedling stage in the greenhouse. GWAS identified 12 quantitative trait loci (QTL) significantly (P ≤ 0.001) associated to stripe rust resistance using the field data of at least two environments and 18 QTL using the seedling data with two races. Among these QTL, 10 were presumably novel, including 4 for adult-plant resistance mapped to chromosomes 1B (QYrcl.sicau-1B.3), 4A (QYrcl.sicau-4A.3), 6A (QYrcl.sicau-6A.2) and 7B (QYrcl.sicau-7B.2) and 6 for all-stage resistance mapped to chromosomes 2D (QYrcl.sicau-2D.1), 3B (QYrcl.sicau-3B.3), 3D (QYrcl.sicau-3D), 4B (QYrcl.sicau-4B), 6A (QYrcl.sicau-6A.1) and 6D (QYrcl.sicau-6D). The landraces with stable resistance can be used for developing wheat cultivars with effective resistance to stripe rust.

In this study, we successfully expressed the active 1Ay subunit of Triticum urartu in barley by Agrobacterium-mediated transformation with a transformation efficiency of 19.9%. The results of SDS-PAGE revealed that the expressed proteins of 1Ay subunit were present at some grains of each of 46 original T0 plants, showing identical mobility to those of positive standards of T. urartu grain protein and bacteria expressional proteins. In the T2 generation, three homozygous lines, 2-28, 3-11, and 5-6, were identified. The results of scanning electron microscopy showed an increased amount of protein bodies in these transgenic lines. The main effects in the expression of the 1Ay subunits was a considerable increase in the glutenin content, but a decrease in the contents of gliadins while there were no effects in the contents of albumin, globulin and the total protein. We found that the gluten could not be washed out from the flour obtained from transgenic barley lines when using a Gluten index analyzer and a Farinograph indicating that the transgenic barley lines could not form dough. The lack of x-type HMW-GS and the reduction in number of subunit were inferred as the possible reasons for the inability to form gluten polymer.

Background:Stripe rust, caused by the fungal pathogen Puccinia striiformis f. sp. tritici (Pst), is a serious foliar disease of wheat. Identification of novel stripe-rust resistance genes and cultivation of resistant varieties are considered to be the most effective approaches to control this disease. In this study, we evaluated the infection type (IT), disease severity (DS) and area under the disease progress curve (AUDPC) of 143 Chinese wheat landrace accessions for stripe-rust resistance. Assessments were undertaken in five environments at the adult-plant stage with Pst mixture races under field conditions, in addition, IT was assessed at the seedling stage with two prevalent Pst races (CYR32 and CYR34) under controlled greenhouse conditions. Results:Seventeen accessions showed stable high-level resistance to stripe rust across all environments under field tests,while four accessions showed resistance to the Pst races CYR32 and CYR34 at the all-stage.Combining phenotypic data from the field and greenhouse trials with 6404 markers covering the whole genome, we detected 17quantitative trait locus(QTLs) on 11 chromosomes for IT associated with seedling resistance and 15 QTLs on seven chromosomes for IT, final disease severityor AUDPC associated with adult-plant resistance. Four stable QTLs detected on four chromosomes, which explained 9.99%–23.30% of the phenotypic variation, were simultaneously associated with seedling and adult-plant resistance. Integrating a linkage map of stripe-rust resistance in wheat, 29 QTLs overlapped with previously reported genes or QTLs, while two and oneQTLs conferring seedling and adult-plant resistancerespectively were mapped distantly from previously reported stripe rust resistance genes or QTLs and may be novel resistantloci. Conclusions:Our results provided an integrated view of stripe rust resistance resources in a Chinese wheat landrace diversity panel from the southern autumn-sown spring wheat zone.The identified resistant accessions and resistance loci will be useful in the ongoing effort to develop new wheat cultivars with strong resistance to stripe rust.