Aegilops sharonensis HMW-GSs with unusually large molecular weight improves bread-making quality in wheat-Ae. sharonensis introgression lines.

BACKGROUND: Eighteen wheat (Triticum aestivum-Aegilops sharonensis) introgression lines were generated in the previous study. These lines possessed four types of high molecular weight glutenin subunit (HMW-GS) combinations consisting of one glutenin from Ae. sharonensis (Glu-1Ssh ) plus one or more HMW-GSs from common wheat (Glu-A1, Glu-B1, or Glu-D1). RESULTS: In this study, we conducted quality tests to explore the effects of 1Ssh x2.3 and 1Ssh y2.9 on the processing quality of 18 wheat-Aegilops sharonensis introgression lines. Our data showed that the 1Ssh x2.3 and 1Ssh y2.9 subunits had a positive effect on gluten and baking quality. The bread volume of all these lines was higher than that of the parental wheat line LM3. In these lines, the HMW-GS content and the HMW/LMW ratio of 66-36-11 were higher than those of LM3, and the 66-36-11 line exhibited greatly improved quality parameters in comparison with the parent LM3. CONCLUSION: These results demonstrated that the 1Ssh x2.3 and 1Ssh y2.9 subunits from Ae. sharonensis contributed immensely to gluten strength and bread-baking quality, and proved a positive relationship between the HMW-GS sizes and their effects on dough strength in vivo. The materials developed could be used by breeding programs aiming to increase bread-making quality. © 2022 Society of Chemical Industry.

Identification and validation of a major QTL for kernel length in bread wheat based on two F3 biparental populations.

BACKGROUND: 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. RESULTS: In this study, an F3 biparental population derived from the cross between an EMS mutant BLS1 selected from an EMS-induced wheat genotype LJ2135 (derived from the hybrid progeny of a spelt wheat (T. spelta L.) and a common wheat) mutant bank and a local breeding line 99E18 was used to rapidly identify loci controlling KL based on Bulked Segregant Analysis (BSA) and the wheat 660 K single-nucleotide polymorphism (SNP) array. The highest ratio of polymorphic SNPs was located on chromosome 4A. Linkage map analysis showed that 33 Kompetitive Allele Specific PCR markers were linked to the QTL for KL (Qkl.sicau-BLE18-4A) identified in three environments as well as the best linear unbiased prediction (BLUP) dataset. This QTL explained 10.87-19.30% of the phenotypic variation. Its effect was successfully confirmed in another F3 population with the two flanking markers KASP-AX-111536305 and KASP-AX-110174441. Compared with previous studies and given that the of BLS1 has the genetic background of spelt wheat, the major QTL was likely a new one. A few of predicted genes related to regulation of kernel development were identified in the interval of the detected QTL. CONCLUSION: A major, novel and stable QTL (Qkl.sicau-BLE18-4A) for KL was identified and verified in two F3 biparental populations across three environments. Significant relationships among KL, kernel width (KW) and thousand kernel weight (TKW) were identified. Four predicted genes related to kernel growth regulation were detected in the interval of Qkl.sicau-BLE18-4A. Furthermore, this study laid foundation on subsequent fine mapping work and provided a possibility for breeding of elite wheat varieties.

The wheat AGL6-like MADS-box gene is a master regulator for floral organ identity and a target for spikelet meristem development manipulation.

The AGAMOUS-LIKE6 (AGL6)-like genes are ancient MADS-box genes and are functionally studied in a few model plants. The knowledge of these genes in wheat remains limited. Here, by studying a 'double homoeolog mutant' of the AGL6 gene in tetraploid wheat, we showed that AGL6 was required for the development of all four whorls of floral organs with dosage-dependent effect on floret fertility. Yeast two-hybrid analyses detected interactions of AGL6 with all classes of MADS-box proteins in the ABCDE model for floral organ development. AGL6 was found to interact with several additional proteins, including the G protein ß and γ (DEP1) subunits. Analysis of the DEP1-B mutant showed a significant reduction in spikelet number per spike in tetraploid wheat, while overexpression of AGL6 in common wheat increased the spikelet number per spike and hence the grain number per spike. RNA-seq analysis identified the regulation of several meristem activity genes by AGL6, such as FUL2 and TaMADS55. Our work therefore extensively updated the wheat ABCDE model and proposed an alternative approach to improve wheat grain yield by manipulating the AGL6 gene.

Quick mapping and characterization of a co-located kernel length and thousand-kernel weight-related QTL in wheat.

KEY MESSAGE: 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.

Characterization and fine mapping of a lesion mimic mutant (Lm5) with enhanced stripe rust and powdery mildew resistance in bread wheat (Triticum aestivum L.).

KEY MESSAGE: A novel light intensity-dependent lesion mimic mutant with enhanced disease resistance was physiologically, biochemically, and genetically characterized, and the causative gene was fine mapped to a 1.28 Mbp interval containing 17 high-confidence genes. Lesion mimic mutants are ideal for studying disease resistance and programmed cell death photosynthesis in plants to improve crop yield. In this study, a novel light intensity-dependent lesion mimic mutant (MC21) was obtained from the wheat variety Chuannong16 (CN16) by ethyl methane sulfonate treatment. The mutant initially developed tiny lesion spots on the basal part of the leaves, which then gradually proceeded down to leaf sheaths, stems, shells, and awns at the flowering stage. The major agronomic traits were significantly altered in the mutant compared to that in the wild-type CN16. Furthermore, the mutant exhibited a lesion phenotype with degenerated chloroplast structure, decreased chlorophyll content, increased level of reactive oxygen species, and increased resistance to stripe rust and powdery mildew. Genetic analysis indicated that the lesion phenotype was controlled by a novel single semi-dominant nuclear gene. The target gene was mapped on chromosome arm 2AL located between Kompetitive Allele Specific PCR (KASP) markers, KASP-4211 and KASP-5353, and tentatively termed as lesion mimic 5 (Lm5). The fine mapping suggested that Lm5 was located in a 1.28 Mbp interval between markers KASP-5825 and KASP-9366; 17 high-confidence candidate genes were included in this genomic region. This study provides an important foundational step for further cloning of Lm5 using a map-based approach.

Regulation of Amylose Content by Single Mutations at an Active Site in the Wx-B1 Gene in a Tetraploid Wheat Mutant.

The granule-bound starch synthase I (GBSSI) encoded by the waxy gene is responsible for amylose synthesis in the endosperm of wheat grains. In the present study, a novel Wx-B1 null mutant line, M3-415, was identified from an ethyl methanesulfonate-mutagenized population of Chinese tetraploid wheat landrace Jianyangailanmai (LM47). The gene sequence indicated that the mutated Wx-B1 encoded a complete protein; this protein was incompatible with the protein profile obtained using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which showed the lack of Wx-B1 protein in the mutant line. The prediction of the protein structure showed an amino acid substitution (G470D) at the edge of the ADPG binding pocket, which might affect the binding of Wx-B1 to starch granules. Site-directed mutagenesis was further performed to artificially change the amino acid at the sequence position 469 from alanine (A) to threonine (T) (A469T) downstream of the mutated site in M3-415. Our results indicated that a single amino acid mutation in Wx-B1 reduces its activity by impairing its starch-binding capacity. The present study is the first to report the novel mechanism underlying Wx-1 deletion in wheat; moreover, it provided new insights into the inactivation of the waxy gene and revealed that fine regulation of wheat amylose content is possible by modifying the GBSSI activity.

Analysis of starch structure and functional properties of tetraploid wheat (Triticum turgidum L.) with differing waxy protein composition.

BACKGROUND: An increased demand for food has mirrored the increasing global population. Obesity and diabetes are two disorders induced by poor eating choices. Consequently, there is an urgent need to develop modified foods that can ameliorate such illnesses. The objective of this study was to explore the effect of Waxy genes on the structural and functional properties of starch, with the aim of improving food quality. Wild-type tetraploid wheat was compared with three mutants with different Waxy gene combinations. RESULTS: The proportion of B-type granules was higher in the mutants than in the wild-type (Wx-AB), and there were significant changes in the starch granule size, number, and phenotype in the Wx free mutant (Wx-ab). The lowest branch chain length was observed in Wx-ab, whereas Wx-AB had the highest branch chain length of DP ≥ 37. Wx-ab had the highest degree of crystallinity. The crystallinity trend followed the order Wx-ab>Wx-Ab>Wx-aB>Wx-AB. The amount of slowly digestible starch (SDS) was higher in native, gelatinized, and retrograded starch in the mutant. The amount of retrograded starch was closer to gelatinized starch than to native starch. CONCLUSION: Waxy proteins make a substantial contribution to starch structure. A lack of waxy proteins reduced the unit chains markedly compared with the control. Waxy proteins significantly affected the smaller and longer chains of starch. The lines with differing waxy composition had different effects on food digestion. The Wx-AB in native starch and Wx-Ab in gelatinized starch can control obesity and diabetes by slow-digesting carbohydrates and high resistance to digestion. © 2022 Society of Chemical Industry.

A single base change at exon of Wx-A1 caused gene inactivation and starch properties modified in a wheat EMS mutant line.

BACKGROUND: Wheat is an essential source of starch. The GBSS or waxy genes are responsible for synthesizing amylose in cereals. The present study identified a novel Wx-A1 null mutant line from an ethyl methanesulfonate (EMS)-mutagenized population of common wheat cv. SM126 using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and agarose gel analyses. RESULTS: The alignment of the Wx-A1 gene sequences from the mutant and parental SM126 lines showed only one single nucleotide polymorphism causing the appearance of a premature stop codon and Wx-A1 inactivation. The lack of Wx-A1 protein resulted in decreased amylose, total starch and resistant starch. The starch morphology assessment revealed that starch from mutant seeds was more wrinkled, increasing its susceptibility to digestion. Regarding the starch thermodynamic properties, the gelatinization temperature was remarkably reduced in the mutant compared to parental line SM126. The digestibility of native, gelatinized, and retrograded starches was analyzed for mutant M4-627 and the parental SM126 line. In the M4-627 line, rapidly digestible starch contents were increased, whereas resistant starch was decreased in the three types of starch. CONCLUSION: Waxy protein is essential for starch synthesis. The thermodynamic characteristics were decreased in the Wx-A1 mutant line. The digestibility properties of starch were also affected. Therefore, the partial waxy mutant M3-627 might play a significant role in food improvement. Furthermore, it might also be used to produce high-quality noodles. © 2021 Society of Chemical Industry.

Genetic identification and characterization of chromosomal regions for kernel length and width increase from tetraploid wheat.

BACKGROUND: Improvement of wheat gercTriticum aestivum L.) yield could relieve global food shortages. Kernel size, as an important component of 1000-kernel weight (TKW), is always a significant consideration to improve yield for wheat breeders. Wheat related species possesses numerous elite genes that can be introduced into wheat breeding. It is thus vital to explore, identify, and introduce new genetic resources for kernel size from wheat wild relatives to increase wheat yield. RESULTS: In the present study, quantitative trait loci (QTL) for kernel length (KL) and width (KW) were detected in a recombinant inbred line (RIL) population derived from a cross between a wild emmer accession 'LM001' and a Sichuan endemic tetraploid wheat 'Ailanmai' using the Wheat 55 K single nucleotide polymorphism (SNP) array-based constructed linkage map and phenotype from six different environments. We identified eleven QTL for KL and KW including two major ones QKL.sicau-AM-3B and QKW.sicau-AM-4B, the positive alleles of which were from LM001 and Ailanmai, respectively. They explained 17.57 to 44.28% and 13.91 to 39.01% of the phenotypic variance, respectively. For these two major QTL, Kompetitive allele-specific PCR (KASP) markers were developed and used to successfully validate their effects in three F3 populations and two natural populations containing a panel of 272 Chinese wheat landraces and that of 300 Chinese wheat cultivars, respectively. QKL.sicau-AM-3B was located at 675.6-695.4 Mb on chromosome arm 3BL. QKW.sicau-AM-4B was located at 444.2-474.0 Mb on chromosome arm 4BL. Comparison with previous studies suggested that these two major QTL were likely new loci. Further analysis indicated that the positive alleles of QKL.sicau-AM-3B and QKW.sicau-AM-4B had a great additive effect increasing TKW by 6.01%. Correlation analysis between KL and other agronomic traits showed that KL was significantly correlated to spike length, length of uppermost internode, TKW, and flag leaf length. KW was also significantly correlated with TKW. Four genes, TRIDC3BG062390, TRIDC3BG062400, TRIDC4BG037810, and TRIDC4BG037830, associated with kernel development were predicted in physical intervals harboring these two major QTL on wild emmer and Chinese Spring reference genomes. CONCLUSIONS: Two stable and major QTL for KL and KW across six environments were detected and verified in three biparental populations and two natural populations. Significant relationships between kernel size and yield-related traits were identified. KASP markers tightly linked the two major QTL could contribute greatly to subsequent fine mapping. These results suggested the application potential of wheat related species in wheat genetic improvement.

QTL mapping and validation of bread wheat flag leaf morphology across multiple environments in different genetic backgrounds.

KEY MESSAGE: 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.

Genome-wide identification of bZIP transcription factor genes related to starch synthesis in barley (Hordeum vulgare L.).

The basic leucine zipper (bZIP) family of genes encode transcription factors that play key roles in plant growth and development. In this study, a total of 92 HvbZIP genes were identified and compared with previous studies using recently released barley genome data. Two novel genes were characterized in this study, and some misannotated and duplicated genes from previous studies have been corrected. Phylogenetic analysis results showed that 92 HvbZIP genes were classified into 10 groups and three unknown groups. The gene structure and motif distribution of the three unknown groups implied that the genes of the three groups may be functionally different. Expression profiling indicated that the HvbZIP genes exhibited different patterns of spatial and temporal expression. Using qRT-PCR, more than 10 HvbZIP genes were identified with expression patterns similar to those of starch synthase genes in barley. Yeast one-hybrid analysis revealed that two of the HvbZIP genes exhibited in vitro binding activity to the promoter of HvAGP-S. The two HvbZIP genes may be candidate genes for further study to explore the mechanism by which they regulate the synthesis of barley starch.

Post-translational cleavage of HMW-GS Dy10 allele improves the cookie-making quality in common wheat (Triticum aestivum).

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. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-021-01238-9.

Major Facilitator Superfamily Transporter Gene FgMFS1 Is Essential for Fusarium graminearum to Deal with Salicylic Acid Stress and for Its Pathogenicity towards Wheat.

Wheat is a major staple food crop worldwide, due to its total yield and unique processing quality. Its grain yield and quality are threatened by Fusarium head blight (FHB), which is mainly caused by Fusarium graminearum. Salicylic acid (SA) has a strong and toxic effect on F. graminearum and is a hopeful target for sustainable control of FHB. F. graminearum is capable of efficientdealing with SA stress. However, the underlying mechanisms remain unclear. Here, we characterized FgMFS1 (FGSG_03725), a major facilitator superfamily (MFS) transporter gene in F. graminearum. FgMFS1 was highly expressed during infection and was upregulated by SA. The predicted three-dimensional structure of the FgMFS1 protein was consistent with the schematic for the antiporter. The subcellular localization experiment indicated that FgMFS1 was usually expressed in the vacuole of hyphae, but was alternatively distributed in the cell membrane under SA treatment, indicating an element of F. graminearum in response to SA. ΔFgMFS1 (loss of function mutant of FgMFS1) showed enhanced sensitivity to SA, less pathogenicity towards wheat, and reduced DON production under SA stress. Re-introduction of a functional FgMFS1 gene into ∆FgMFS1 recovered the mutant phenotypes. Wheat spikes inoculated with ΔFgMFS1 accumulated more SA when compared to those inoculated with the wild-type strain. Ecotopic expression of FgMFS1 in yeast enhanced its tolerance to SA as expected, further demonstrating that FgMFS1 functions as an SA exporter. In conclusion, FgMFS1 encodes an SA exporter in F. graminearum, which is critical for its response to wheat endogenous SA and pathogenicity towards wheat.

A novel, major, and validated QTL for the effective tiller number located on chromosome arm 1BL in bread wheat.

KEY MESSAGE: A novel and major QTL for the effective tiller number was identified on chromosomal arm 1BL and validated in two genetic backgrounds The effective tiller number (ETN) substantially influences plant architecture and the wheat yield improvement. In this study, we constructed a genetic map of the 2SY (20828/SY95-71) recombinant inbred line population based on the Wheat 55K array as well as the simple sequence repeat (SSR) and Kompetitive Allele Specific PCR (KASP) markers. A comparison between the genetic and physical maps indicated the marker positions were consistent in the two maps. Additionally, we identified seven tillering-related quantitative trait locus (QTLs), including Qetn-sau-1B.1, which is a major QTL localized to a 6.17-cM interval flanked by markers AX-89635557 and AX-111544678 on chromosome 1BL. The Qetn-sau-1B.1 QTL was detected in eight environments and explained 12.12-55.71% of the phenotypic variance. Three genes associated with the ETN were detected in the physical interval of Qetn-sau-1B.1. We used a tightly linked KASP marker, KASP-AX-110129912, to further validate this QTL in two other populations with different genetic backgrounds. The results indicated that Qetn-sau-1B.1 significantly increased the ETN by up to 23.5%. The results of this study will be useful for the precise mapping and cloning of Qetn-sau-1B.1.

Identification and characterization of mRNAs and lncRNAs of a barley shrunken endosperm mutant using RNA-seq.

Barley shrunken endosperm mutants have been extensively reported. However, knowledge of the underlying molecular mechanisms of these mutants remains limited. Here, a pair of near isogenic lines (normal endosperm: Bowman and shrunken endosperm: sex1) was subjected to transcriptome analysis to identify mRNAs and lncRNAs related to endosperm development to further dissect its mechanism of molecular regulation. A total of 2123 (1140 up- and 983 down-regulated) unique differentially expressed genes (DEGs) were detected. Functional analyses showed that these DEGs were mainly involved in starch and sucrose metabolism, biosynthesis of secondary metabolites, and plant hormone signal transduction. A total of 343 unique target genes were identified for 57 differentially expressed lncRNAs (DE lncRNAs). These DE lncRNAs were mainly involved in glycerophospholipid metabolism, starch and sucrose metabolism, hormone signal transduction, and stress response. In addition, key lncRNAs were identified by constructing a co-expression network of the target genes of DE lncRNAs. Transcriptome results suggested that mRNA and lncRNA played a critical role in endosperm development. The shrunken endosperm in barley seems to be closely related to plant hormone signal transduction, starch and sucrose metabolism, and cell apoptosis. This study provides a foundation for fine mapping, elucidates the molecular mechanism of shrunken endosperm mutants, and also provides a reference for further studies of lncRNAs during the grain development of plants.

A novel, validated, and plant height-independent QTL for spike extension length is associated with yield-related traits in wheat.

KEY MESSAGE: 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.

Flag leaf size and posture of bread wheat: genetic dissection, QTL validation and their relationships with yield-related traits.

KEY MESSAGE: Major and environmentally stable QTL for flag leaf-related traits in wheat were identified and validated across ten environments using six populations with different genetic backgrounds. Flag leaf size and posture are two important factors of "ideotype" in wheat. Despite numerous studies on genetic analysis of flag leaf size including flag leaf length (FLL), width (FLW), area (FLA) and the ratio of length/width (FLR), few have focused on flag leaf posture including flag leaf angle (FLANG), opening angle (FLOA) and bend angle (FLBA). Further, the numbers of major, environmentally stable and verified genetic loci for flag leaf-related traits are limited. In this study, QTL for FLL, FLW, FLA, FLR, FLANG, FLOA and FLBA were identified based on a recombinant inbred line population together with values from up to ten different environments. Totally, eight major and stably expressed QTL were identified. Three co-located chromosomal intervals for seven major QTL were identified. The five major QTL QFll.sicau-5B.3 and QFll.sicau-2D.3 for FLL, QFlr.sicau-5B for FLR, QFlw.sicau-2D for FLW and QFla.sicau-2D for FLA were successfully validated by the tightly linked Kompetitive Allele Specific PCR (KASP) markers in the other five populations with different genetic backgrounds. A few genes related to leaf growth and development in intervals for these major QTL were predicated. Significant relationships between flag leaf- and yield-related traits were evidenced by analyses of Pearson correlations, conditional QTL and genetic mapping. Taken together, these results provide valuable information for understanding flag leaf size and posture of "ideotype" as well as fine mapping and breeding utilization of promising loci in bread wheat.

Correction to: Identification and validation of a major and stably expressed QTL for spikelet number per spike in bread wheat.

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

The production of wheat - Aegilops sharonensis 1Ssh chromosome substitution lines harboring alien novel high-molecular-weight glutenin subunits.

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.

Quantitative trait loci for seeding root traits and the relationships between root and agronomic traits in common wheat.

A completely developed and vigorous root system can provide a stable platform for aboveground plant organs. To identify loci controlling root traits that could be used in wheat (Triticum aestivum L.) breeding, 199 recombinant inbred lines were used to measure and analyze eight root traits. A total of 18 quantitative trait loci (QTL) located on chromosomes 1A, 2A, 2B, 2D, 4B, 4D, 6A, 7A, and 7B were identified. The phenotypic variation explained by these 18 QTL ranged from 3.27% to 11.75%, and the logarithm of odds scores ranged from 2.50 to 6.58. A comparison of physical intervals indicated several new QTL for root traits were identified. In addition, significant correlations between root and agronomic traits were detected and discussed. The results presented in this study, along with those of previous reports, suggest that chromosomes 2 and 7 likely play important roles in the growth and development of wheat roots.