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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 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.

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.

The spike traits of wheat can directly affect yield. F(2) and F(2:3) lines derived from the cross of the multi-spikelet female 10-A and the uni-spikelet male BE89 were used to detect QTLs for spike length (SL), total spikelet number per spike (TSS), kernel number per spike (KNS) and thousand-kernel weight (TKW) in four different environments. A total of 1098 SNP and 5 SSR were used to construct genetic map of 2398.1 cM with the average distance of 2.2 cM between markers. A total of 11 QTLs were identified for spike traits, including three QTLs for SL, five QTLs for TSS, two QTLs for KNS and one QTL for TKW. The QTLs mapped to chromosomes 2D, 4A, 6A, 7A and 7B explained 8.2–37.8% of the phenotypic variation in single environment. The major QTL confidence interval with distance of 0.5 cM was located on chromosome 4A and detected in multiple environments, which can explain more than 30% of the phenotypic variation for SL, TSS and KNS. Combining IWGSC RefSeq v1.0 and RNA-seq data for 10-A and BE89, we identified 16 genes expressed on spike or grain in four QTL regions. These findings provide insights into improving wheat yield through increasing spikletes in wheat, particularly through the use of the multi-spikelet female 10-A for breeding. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12298-020-00823-0) contains supplementary material, which is available to authorized users.

In our previous study, we have isolated novel HMW-GSs with unusually large molecular weight from Aegilops sharonensis; and to introduce this novel HMW-GSs variant into common wheat, we produced a number of amphiploids between various tetraploid wheat, hexaploid wheat and Ae. sharonensis by distant hybridization. In this study, we reported that the characterization of 24 HMW-GSs homozygous lines from wheat-Ae. sharonensis populations derived by continuous backcross or self-cross to common wheat cultivar LM3, which possessed homozygous HMW-GSs compositions including alien HMW-GS of Ae. sharonensis plus B and/or D genomes encoded HMW-GSs of LM3. According to the profiling of HMW-GS, these 24 homozygous lines can be summarized as four types. The results of Non-denaturing fluorescence in situ hybridization (ND-FISH) indicated that the chromosome numbers of eight of 24 lines were 40, 42, 44 or 45, and the number of alien Ae. sharonensis Ssh were between two and eight. Three 1S(1A) substitution lines, two 1S(1B) substitution lines, three 1S(1D) substitution lines. For the four lines with 44 and 45 chromosomes, they exhibit novel cytogenetic characteristics in which the substitution of 1S(1B) or 1S(1D) and addition of Ae. sharonensis 3S or 4S simultaneously appeared. The 24 homozygous progenies were similar to common wheat LM3 on agronomic traits. Specially, four lines of them showed almost identical agronomic traits to recurrent parent common wheat LM3 than the rest lines. These homozygous progenies could be used not only to evaluate function on quality of single HMW-GS but also to create translocation lines.

The jasmonate-regulated protein Ta-JA1 belongs to the monocot chimeric jacalin (MCJ) family and plays a vital role in stress resistance in wheat. However, the impact of wheat polyploidization on Ta-JA1 remains unclear. In this study, 149 members of the MCJ family were identified among members of Triticeae using a genome-wide approach. The genes were resolved into three clades; MCJ genes in each clade were derived from different donor genes during evolution. Segmental duplication may have been the primary driver, compared with tandem duplication, of expansion in the MCJ family of wheat. Gene loss and acquisition occurred during tetraploidization, and the core expansion of the family occurred after tetraploidization. Sequencing data for 2104 accessions of T. aestivum and 99 accessions of T. dicoccoides showed that Ta-JA1-2A and Ta-JA1 were highly conserved in common wheat, and four alleles (TdJA1-Ax2, TdJA1-Ay2, TdJA1-Ax3, and TdJA1-Ay3) were detected in T. dicoccoides. Using gene-specific markers, one AsJA1-B allele was detected in 11 Ae. speltoides accessions and one TuJA1-Ax1 allele was detected in 70 T. urartu accessions. Six alleles were detected on chromosome 2A: TdJA1-Ax1 (13 accessions), TdJA1-Ay1 (57 accessions), TdJA1-Ax2 (23 accessions), TdJA1-Ay2 (42 accessions), TdJA1-Ax3 (29 accessions), and TdJA1-Ay3 (251 accessions). Only one allele (TdJA1-B) on chromosome 2B was detected in 415 T. dicoccoides accessions. A geographical distribution analysis revealed that Israel hosted higher allelic variation than other regions. Quantitative reverse transcription PCR analysis indicated that divergence in expression has occurred among Ta-JA1 alleles and, notably, TdJA1-Ax1 and TdJA1-Ay1 showed significantly higher expression levels than the other four allelic types in T. dicoccoides. The present results contribute to an improved understanding of the effects of polyploidization on the MCJ gene family and the functions of Ta-JA1, and may be useful to enrich common wheat germplasm resources.

As an essential mineral element, selenium (Se) plays a critical role in human health. Given the low concentrations ( stem > grain. This is the first study to document a Se-rich synthetic wheat line, and root structure and Se grain concentration was strongly affected by QTL located on 3D.

Although DNA elimination, gene silencing and duplication and pseudogenization are associated with allopolyploidization in wheat, the effect of allopolyploidy on the ecogeographical expansion and domestication of this species remains unknown. In the present study, we used 1862 mapped loci to investigate genetic changes associated with allopolyploidization by comparing bands between synthetic wheat SHW-L1 and its parental lines Aegilops tauschii ssp. tauschii AS60 (DD) and Triticum turgidum ssp. turgidum AS2255 (AABB). A total of 338 (18.15%) loci from AS60 or AS2255 were found to have been eliminated from SHW-L1. Of these loci, 56 were present only in AS2255; 212 ones were found only in AS60 and 70 ones were detected in both AS2255 and AS60. The different numbers of eliminated loci originating from AS2255 and AS60 suggest that the D genome of SHW-L1 suffered more disruption during the allopolyploidization process than the A and B genomes. In addition, 82 eliminated loci were tightly linked to express quantitative trait loci, with 53 of these loci containing open reading frame sequences predicted to encode proteins related to disease resistance, environmental adaption, nitrogen fixation, nitrogenase reductase and other processes. Further investigation of changes in these gene sequences should help elucidate the genetic mechanisms underlying the increased fitness, adaptability and competitiveness that have accompanied wheat during domestication.

In our previous work, a novel high-molecular-weight glutenin subunit (HMW-GS) with an extremely large molecular weight from

Unfortunately, the author contribution statement was missed out in the original publication. The complete statement is given below.

Background Kernel length (KL), kernel width (KW) and thousand-kernel weight (TKW) are key agronomic traits in wheat breeding. Chuannong16 (‘CN16’) is a commercial cultivar with significantly longer kernels than the line ‘20828’. To identify and characterize potential alleles from CN16 controlling KL, the previously developed recombinant inbred line (RIL) population derived from the cross ‘20828’ × ‘CN16’ and the genetic map constructed by the Wheat55K SNP array and SSR markers were used to perform quantitative trait locus/loci (QTL) analyses for kernel traits. Results A total of 11 putative QTL associated with kernel traits were identified and they were located on chromosomes 1A (2 QTL), 2B (2 QTL), 2D (3 QTL), 3D, 4A, 6A, and 7A, respectively. Among them, three major QTL, QKL.sicau-2D, QKW.sicau-2D and QTKW.sicau-2D, controlling KL, KW and TKW, respectively, were detected in three different environments. Respectively, they explained 10.88–18.85%, 17.21–21.49% and 10.01–23.20% of the phenotypic variance. Further, they were genetically mapped in the same interval on chromosome 2DS. A previously developed kompetitive allele-specific PCR (KASP) marker KASP-AX-94721936 was integrated in the genetic map and QTL re-mapping finally located the three major QTL in a 1- cM region flanked by AX-111096297 and KASP-AX-94721936. Another two co-located QTL intervals for KL and TKW were also identified. A few predicted genes involved in regulation of kernel growth and development were identified in the intervals of these identified QTL. Significant relationships between kernel traits and spikelet number per spike and anthesis date were detected and discussed. Conclusions Three major and stably expressed QTL associated with KL, KW, and TKW were identified. A KASP marker tightly linked to these three major QTL was integrated. These findings provide information for subsequent fine mapping and cloning the three co-localized major QTL for kernel traits.

In this study, we successfully knock-out the d-hordein component of barley storage protein using RNA-guided Cas9. Mutation frequencies of 25% and 14% at two different target sites were obtained. Homozygous mutant plants that were T-DNA free were identified in the T1 generation. Barley grains without d-hordein proteins from T2 seeds showed a significantly reduced grain size compared to the parent plant and control non-edited line. The protein matrix surrounding the starch granules was increased, whereas the starch granules themselves were decreased in size in the mutant plants compared to controls. The main effect of a lack of d-hordein was a considerable decrease in the prolamines and an increase in the glutenins. The changes of other grain composition included the increased starch content, amylose content, and β-glucan content. The roles of d-hordein mutation on barley grain size and grain composition remain to be studied.

Terpenoids play important roles in plant defense. Although some terpene synthases have been characterized, terpenoids and their biosynthesis in wheat (Triticum aestivum L.) still remain largely unknown. Here, we describe the identification of a terpene synthase gene in wheat. It encodes a sesquiterpene synthase that catalyzes &beta, patchoulene formation with E,E-farnesyl diphosphate (FPP) as the substrate, thus named as TaPS. TaPS exhibits inducible expression in wheat in response to various elicitations. Particularly, alamethicin treatment strongly induces TaPS gene expression and &beta, patchoulene accumulation in wheat. Overexpression of TaPS in Arabidopsis successfully produces &beta, patchoulene, verifying the biochemical function of TaPS in planta. Furthermore, these transgenic Arabidopsis plants exhibit resistance against herbivory by repelling beet armyworm larvae feeding, thereby indicating anti-herbivory activity of &beta, patchoulene. The catalytic mechanism of TaPS is also explored by homology modeling and site-directed mutagenesis. Two key amino acids are identified to act in protonation and stability of intermediates and product formation. Taken together, one wheat sesquiterpene synthase is identified as &beta, patchoulene synthase. TaPS exhibits inducible gene expression and the sesquiterpene &beta, patchoulene is involved in repelling insect infestation.

Phosphoglucan phosphatases (Like-SEX4 1 and 2; LSF1 and LSF2) were reported to play roles in starch metabolism in leaves of Arabidopsis. In this study, we identified and mapped the LSF1 and LSF2 genes in barley (HvLSF1 and HvLSF2), characterized their gene and protein structures, predicted the cis-elements of their promoters, and analysed their expression patterns. HvLSF1 and HvLSF2 were mapped on the long arm of chromosome 1H (1HL) and 5H (5HL), respectively. Our results revealed varied exon-intron structures and conserved exon-intron junctions in both LSF1 and LSF2 from a range of analysed species. Alignment of protein sequences indicated that cTP and CT domains are much less varied than the functional domains (PDZ, DPS and CBM48). LSF2 was mainly expressed in anthers of barley and rice, and in leaf of Arabidopsis. LSF1 was mainly expressed in endosperm of barley and leaf of Arabidopsis and rice. The expression of LSF1 exhibited a diurnal pattern in rice only and that of LSF2 in both rice and Arabidopsis. Of the investigated stresses, only cold stress significantly reduced expression level of LSF1 and LSF2 in barley and LSF2 in Arabidopsis at late stages of the treatments. While heat treatment significantly decreased expression levels of LSF1 at middle stage (4 h) of a treatment in Arabidopsis only. The strong relationships detected between LSF2 and starch excess4 (SEX4), glucan, water dikinases or phosphoglucan, water dikinases were identified and discussed. Taken together, these results provide information of genetic manipulation of LSF1 and LSF2, especially in monocotyledon and further elucidate their regulatory mechanism in plant development.

Chromosome translocation is an important driving force in shaping genomes during evolution. Detailed knowledge of chromosome translocations in a given species and its close relatives should increase the efficiency and precision of chromosome engineering in crop improvement. To identify genes flanking the breakpoints of translocations and inversions as a step toward identifying breakpoints in bread wheat, we systematically analysed genes in the Brachypodium genome against wheat survey sequences and bin-mapped ESTs (expressed sequence tags) derived from the hexaploid wheat genotype ‘Chinese Spring’. In addition to those well-known translocations between group 4, 5, and 7 chromosomes, this analysis identified genes flanking the three pericentric inversions on chromosomes 2B, 4B, and 5A. However, numerous chromosomal rearrangements reported in early studies could not be confirmed. The genes flanking the breakpoints reported in this study are valuable for isolating these breakpoints.

Waxy gene plays a key role for amylose synthesis in wheat seeds. The study evaluated the Waxy gene variability in 59 accessions of six diploid Triticum and Aegilops species. The percentages of variable sites, singleton variable sites, and parsimony informative sites were 16.38, 5.59, and 10.79 %, respectively. A total of 22 amino acid changes in the transit peptide and the remaining in the mature protein were observed. Moreover, 17 amino acid changes between Triticum and Aegilops species were also detected. Specially, Gla 14 and Phe 153 was observed in diploid Triticum, compared with Thr 14 and Tyr 153 in diploid Aegilops. Two types of amino acids, Gla 5/Val 5 and Ile 140/Val 140, were identified in T. urartu, as well as Val 22/Phe 22, Thr 52/Lys 52, and Gln 54/delete in A. tauschii. The insertion/deletions (InDels) had high frequency in intron region, but very low in transit peptide and exon region. Neighbour-joining tree showed that 146 sequences from 23 species could be clustered into eight groups with the species characterizations. The Wx-B1 of polyploid Triticum were grouped with A. sharonensis, A. longissima, A. searsii, A. speltoides, while Wx-D1 of T. aestivum and T. spelta together with A. umbellulata, A. markgrafii, A. comosa, and A. tauschii. The Wx-A1 of polyploid Triticum were separated clearly with the diploid species. The Wx-B1 could be divided into two subgroups and maybe had two phylogenetic origins, but most of them were related to A. speltoides. Waxy gene of A. tauschii also had two subgroups, and the sequences from southern Caspian (Mazandaran, Iran) were more closed with Wx-D1. The variability of 5′ Un-Translation Region (UTR) of waxy was stronger than intron and exon region based on genetic distance. Phylogeography analysis showed that geography affected strongly the distribution of all accessions along the north–south axis based on the partial open reading fragment (ORF) of waxy gene, A. speltoides and A. longissima along the west–east axis and north–south axis based on exon, and A. tauschii along the west–east axis based on 5′ UTR, respectively. Our results suggest that diploid Triticum and Aegilops have new waxy gene resources; waxy gene could play a more important role in genetic exploitation, genetic relationship evaluation and phylogeography investigation.