Chromosome stability of synthetic Triticum turgidum-Aegilops umbellulata hybrids.

BACKGROUND: Unreduced gamete formation during meiosis plays a critical role in natural polyploidization. However, the unreduced gamete formation mechanisms in Triticum turgidum-Aegilops umbellulata triploid F1 hybrid crosses and the chromsome numbers and compostions in T. turgidum-Ae. umbellulata F2 still not known. RESULTS: In this study, 11 T.turgidum-Ae. umbellulata triploid F1 hybrid crosses were produced by distant hybridization. All of the triploid F1 hybrids had 21 chromosomes and two basic pathways of meiotic restitution, namely first-division restitution (FDR) and single-division meiosis (SDM). Only FDR was found in six of the 11 crosses, while both FDR and SDM occurred in the remaining five crosses. The chromosome numbers in the 127 selfed F2 seeds from the triploid F1 hybrid plants of 10 crosses (no F2 seeds for STU 16) varied from 35 to 43, and the proportions of euploid and aneuploid F2 plants were 49.61% and 50.39%, respectively. In the aneuploid F2 plants, the frequency of chromosome loss/gain varied among genomes. The chromosome loss of the U genome was the highest (26.77%) among the three genomes, followed by that of the B (22.83%) and A (11.81%) genomes, and the chromosome gain for the A, B, and U genomes was 3.94%, 3.94%, and 1.57%, respectively. Of the 21 chromosomes, 7U (16.54%), 5 A (3.94%), and 1B (9.45%) had the highest loss frequency among the U, A, and B genomes. In addition to chromosome loss, seven chromosomes, namely 1 A, 3 A, 5 A, 6 A, 1B, 1U, and 6U, were gained in the aneuploids. CONCLUSION: In the aneuploid F2 plants, the frequency of chromosome loss/gain varied among genomes, chromsomes, and crosses. In addition to variations in chromosome numbers, three types of chromosome translocations including 3UL·2AS, 6UL·1AL, and 4US·6AL were identified in the F2 plants. Furthermore, polymorphic fluorescence in situ hybridization karyotypes for all the U chromosomes were also identified in the F2 plants when compared with the Ae. umbellulata parents. These results provide useful information for our understanding the naturally occurred T. turgidum-Ae. umbellulata amphidiploids.

Disomic 1M (1B) Triticum aestivum-Aegilops comosa Substitution Line with Favorable Protein Properties.

Aegilops comosa (2n = 2x = 14, MM) contains many excellent genes/traits for wheat breeding. Wheat-Ae. comosa introgression lines have potential value in the genetic improvement of wheat quality. A disomic 1M (1B) Triticum aestivum-Ae. comosa substitution line NAL-35 was identified by fluorescence in situ hybridization and genomic in situ hybridization analysis from a hybridization cross between a disomic 1M (1D) substitution line NB 4-8-5-9 with CS N1BT1D. The observation of pollen mother cells showed that NAL-35 had normal chromosome pairing, suggesting that NAL-35 could be used for the quality test. NAL-35 with alien Mx and My subunits showed positive effects on some protein-related parameters including high protein content and high ratios of high-molecular-weight glutenin subunits (HMW-GSs)/glutenin and HMW-GS/low-molecular-weight glutenin subunits. The changes in gluten composition improved the rheological properties of the dough of NAL-35, resulting in a tighter and more uniform microstructure. NAL-35 is a potential material for wheat quality improvement that transferred quality-related genes from Ae. comosa.

HFR1, a bHLH Transcriptional Regulator from Arabidopsis thaliana, Improves Grain Yield, Shade and Osmotic Stress Tolerances in Common Wheat.

Common wheat, Triticum aestivum, is the most widely grown staple crop worldwide. To catch up with the increasing global population and cope with the changing climate, it is valuable to breed wheat cultivars that are tolerant to abiotic or shade stresses for density farming. Arabidopsis LONG HYPOCOTYL IN FAR-RED 1 (AtHFR1), a photomorphogenesis-promoting factor, is involved in multiple light-related signaling pathways and inhibits seedling etiolation and shade avoidance. We report that overexpression of AtHFR1 in wheat inhibits etiolation phenotypes under various light and shade conditions, leading to shortened plant height and increased spike number relative to non-transgenic plants in the field. Ectopic expression of AtHFR1 in wheat increases the transcript levels of TaCAB and TaCHS as observed previously in Arabidopsis, indicating that the AtHFR1 transgene can activate the light signal transduction pathway in wheat. AtHFR1 transgenic seedlings significantly exhibit tolerance to osmotic stress during seed germination compared to non-transgenic wheat. The AtHFR1 transgene represses transcription of TaFT1, TaCO1, and TaCO2, delaying development of the shoot apex and heading in wheat. Furthermore, the AtHFR1 transgene in wheat inhibits transcript levels of PHYTOCHROME-INTERACTING FACTOR 3-LIKEs (TaPIL13, TaPIL15-1B, and TaPIL15-1D), downregulating the target gene STAYGREEN (TaSGR), and thus delaying dark-induced leaf senescence. In the field, grain yields of three AtHFR1 transgenic lines were 18.2-48.1% higher than those of non-transgenic wheat. In summary, genetic modification of light signaling pathways using a photomorphogenesis-promoting factor has positive effects on grain yield due to changes in plant architecture and resource allocation and enhances tolerances to osmotic stress and shade avoidance response.

Clinical and Preclinical Neuroimaging Changes in Spinocerebellar Ataxia Type 12: A Study of Three Chinese Pedigrees.

BACKGROUND: Spinocerebellar ataxia type 12 (SCA12) is a rare SCA subtype with unclear clinical and imaging features. Also, the radiological changes in prodromal and early stages remain unknown. METHODS: Ten symptomatic and two pre-symptomatic cases from three Chinese pedigrees received clinical assessments and imaging studies including routine magnetic resonance imaging (MRI), diffusion kurtosis imaging (DKI), and positron emission tomography (PET) using 18F-flurodeoxyglucose (FDG) to investigate glucose metabolism in brain and 18F-vesicle monoamine transporter 2 (VMAT2) to inspect the integrity of the dopaminergic neuron. Seventy-two healthy individuals were recruited as controls in the quantitative FDG-PET analysis. Imaging parameters were compared between symptomatic and presymptomatic cases with different disease durations. RESULTS: Patients displayed prominent action tremor, moderate ataxia, and subtle parkinsonism with poor levodopa-response. MRI showed extensive but heterogeneous cerebral atrophy, which was most evident in the frontoparietal lobes. Cerebellar atrophy was apparent in later stages. DKI detected impaired fibers in the cerebellar peduncles. In both symptomatic and pre-symptomatic cases, PET-CT showed an earlier FDG decline than atrophic changes in multiple regions, and the frontoparietal lobes were the earliest and most severe. However, the VMAT2 density were normal in the putamen and caudate nucleus of most cases (7/8). CONCLUSIONS: We first found that hypometabolism in the cerebral cortex, but not cerebellum, is an early and prominent change in SCA12. The integrity of presynaptic dopaminergic neurons remains largely spared during the whole disease process.

Identification and Characterization of Wheat-Aegilops comosa 7M (7A) Disomic Substitution Lines with Stripe Rust and Powdery Mildew Resistance.

Aegilops comosa (MM, 2n = 2x = 14), an important diploid species from the wheat tertiary gene pool, contains many unique genes/traits of potential use for wheat breeding, such as disease resistance. In this study, three sister lines, NAL-32, NAL-33, and NAL-34, were identified from a wheat-A. comosa distant cross using fluorescence in situ hybridization, simple sequence repeat markers, and PCR-based unique gene markers combined with single nucleotide polymorphism (SNP) array analysis. Genetically, NAL-32 contained neither an alien nor translocation chromosome, whereas NAL-33 and NAL-34 had disomic 7M (7A) substitution chromosomes but differed in the absence or presence of the 1BL/1RS translocation chromosomes, respectively. The absence of 7A in NAL-33 and NAL-34 and the unusual 1B in the latter were verified by wheat 55K SNP arrays. The two 7M (7A) substitution lines had similar levels of resistance to stripe rust and powdery mildew, but better than that of NAL-32 and their common wheat parents, suggesting that the stripe rust and powdery mildew resistance of NAL-33 and NAL-34 were derived from the 7M of A. comosa. This research provides important bridge materials that can potentially be used for transferring stripe rust and powdery mildew resistance.

Coupling of brain activity and structural network in multiple sclerosis: A graph frequency analysis study.

The brain activities and the underlying wiring diagrams are vulnerable in multiple sclerosis (MS). Also, it remains unknown whether the complex coupling between these functional and structural brain properties would be affected. To address this issue, we adopted graph frequency analysis to quantify the high-order structural-functional interactions based on a combination of brain diffusion and functional MRI data. The structural-functional decoupling index was proposed to measure how much brain regional functional activity with different graph frequency was organized atop the underlying wiring diagram in MS. The identified patterns in MS included (1) disruption of inherent structural-functional coupling in the somatomotor network (ß = 0.05, p = 0.03), and (2) excessive decrease of decoupling in the subcortical (ß = -0.10, p = 0.02), visual (ß = -0.04, p = 0.01), and dorsal attention networks (ß = -0.12, p = 0.03). Besides, this structural-functional coupling signature in the somatomotor network was associated with cognitive worsening of MS patients (ß = -24.31, p = 0.006). Overall, our study unveiled a unique signature of brain structural-functional reorganization in MS.

Characterization of novel LMW-i genes with nine cysteine residues from Chinese wheat landraces (Triticum aestivum L.) and analysis of their functional properties on dough mixing.

The low-molecular-weight glutenin subunits (LMW-GS) with extra cysteine numbers have attracted great research interest for their potential quality value. In this study, 14 LMW-i type genes (YD1-YD14) were isolated from three types of Chinese wheat landraces; and nine of 14 genes (YD1-YD9) had nine cysteines, and the other five genes contained eight cysteines. Phylogenic analysis suggested that all 14 LMW-i genes were related to Glu-A3-1 variants Glu-A3-17/FJ 549934 and Glu-A3-15/FJ 549932. Six randomly selected genes, five genes including YD 1 with nine cysteines and the remaining one with eight cysteines, were successfully expressed in bacteria as mature proteins with a molecular mass of ~ 46 kDa. These proteins were traced to corresponding seed storage proteins for having similar elution times in reverse phase high-performance liquid chromatography (RP-HPLC) profiles. Mass spectrometry verified that bacterial expressed protein pET-30a-YD1 was LMW-i. Dough mixing experiments for incorporation of 50 mg pET-30a-YD1 proteins into the base flour of weak gluten wheat cv. "Chuannong 16" indicated that the dough strength of mixing flours was noticeably weaker than that of the control, which was reflected by mixing parameters in 8-min curve width, peak width, peak height, mixing time, and right of peak slope. The results suggested that the LMW-i genes with nine cysteine residues in the present study contributed to inferior quality properties for wheat flour. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-03044-8.

A Classification and Prediction Hybrid Model Construction with the IQPSO-SVM Algorithm for Atrial Fibrillation Arrhythmia.

Atrial fibrillation (AF) is the most common cardiovascular disease (CVD), and most existing algorithms are usually designed for the diagnosis (i.e., feature classification) or prediction of AF. Artificial intelligence (AI) algorithms integrate the diagnosis of AF electrocardiogram (ECG) and predict the possibility that AF will occur in the future. In this paper, we utilized the MIT-BIH AF Database (AFDB), which is composed of data from normal people and patients with AF and onset characteristics, and the AFPDB database (i.e., PAF Prediction Challenge Database), which consists of data from patients with Paroxysmal AF (PAF; the records contain the ECG preceding an episode of PAF), and subjects who do not have documented AF. We extracted the respective characteristics of the databases and used them in modeling diagnosis and prediction. In the aspect of model construction, we regarded diagnosis and prediction as two classification problems, adopted the traditional support vector machine (SVM) algorithm, and combined them. The improved quantum particle swarm optimization support vector machine (IQPSO-SVM) algorithm was used to speed the training time. During the verification process, the clinical FZU-FPH database created by Fuzhou University and Fujian Provincial Hospital was used for hybrid model testing. The data were obtained from the Holter monitor of the hospital and encrypted. We proposed an algorithm for transforming the PDF ECG waveform images of hospital examination reports into digital data. For the diagnosis model and prediction model trained using the training set of the AFDB and AFPDB databases, the sensitivity, specificity, and accuracy measures were 99.2% and 99.2%, 99.2% and 93.3%, and 91.7% and 92.5% for the test set of the AFDB and AFPDB databases, respectively. Moreover, the sensitivity, specificity, and accuracy were 94.2%, 79.7%, and 87.0%, respectively, when tested using the FZU-FPH database with 138 samples of the ECG composed of two labels. The composite classification and prediction model using a new water-fall ensemble method had a total accuracy of approximately 91% for the test set of the FZU-FPH database with 80 samples with 120 segments of ECG with three labels.

Genome-Wide Association Study for Grain Micronutrient Concentrations in Wheat Advanced Lines Derived From Wild Emmer.

Wheat is one of the important staple crops as the resources of both food and micronutrient for most people of the world. However, the levels of micronutrients (especially Fe and Zn) in common wheat are inherently low. Biofortification is an effective way to increase the micronutrient concentration of wheat. Wild emmer wheat (Triticum turgidum ssp. dicoccoides, AABB, 2n = 4x = 28) is an important germplasm resource for wheat micronutrients improvement. In the present study, a genome-wide association study (GWAS) was performed to characterize grain iron, zinc, and manganese concentration (GFeC, GZnC, and GMnC) in 161 advanced lines derived from wild emmer. Using both the general linear model and mixed linear model, we identified 14 high-confidence significant marker-trait associations (MTAs) that were associated with GFeC, GZnC, and GMnC of which nine MTAs were novel. Six MTAs distributed on chromosomes 3B, 4A, 4B, 5A, and 7B were significantly associated with GFeC. Three MTAs on 1A and 2A were significantly associated with GZnC and five MTAs on 1B were significantly associated with GMnC. These MTAs show no negative effects on thousand kernel weight (TKW), implying the potential value for simultaneous improvement of micronutrient concentrations and TKW in breeding. Meanwhile, the GFeC, GZnC and GMnC are positively correlated, suggesting that these traits could be simultaneously improved. Genotypes containing high-confidence MTAs and 61 top genotypes with a higher concentration of grain micronutrients were recommended for wheat biofortification breeding. A total of 38 candidate genes related to micronutrient concentrations were identified. These candidates can be classified into four main groups: enzymes, transporter proteins, MYB transcription factor, and plant defense responses proteins. The MTAs and associated candidate genes provide essential information for wheat biofortification breeding through marker-assisted selection (MAS).

A high-quality genome assembly highlights rye genomic characteristics and agronomically important genes.

Rye is a valuable food and forage crop, an important genetic resource for wheat and triticale improvement and an indispensable material for efficient comparative genomic studies in grasses. Here, we sequenced the genome of Weining rye, an elite Chinese rye variety. The assembled contigs (7.74 Gb) accounted for 98.47% of the estimated genome size (7.86 Gb), with 93.67% of the contigs (7.25 Gb) assigned to seven chromosomes. Repetitive elements constituted 90.31% of the assembled genome. Compared to previously sequenced Triticeae genomes, Daniela, Sumaya and Sumana retrotransposons showed strong expansion in rye. Further analyses of the Weining assembly shed new light on genome-wide gene duplications and their impact on starch biosynthesis genes, physical organization of complex prolamin loci, gene expression features underlying early heading trait and putative domestication-associated chromosomal regions and loci in rye. This genome sequence promises to accelerate genomic and breeding studies in rye and related cereal crops.

Production and characterization of a disomic 1M/1D Triticum aestivum-Aegilops comosa substitution line.

PI 554419, formerly designated as Ae. uniaristata, showed significant difference with other Ae. uniaristata and Ae. comosa accessions in morphological traits at the seedling stage and its leaf color, length, and width behaved as an intermediate type. In this study, we reclassified PI 554419 as Ae. comosa subsp. comosa by comparing the fluorescence in situ hybridization (FISH) signals and the patterns of PCR-based landmark unique gene (PLUG) markers and conserved orthologous set (COS) markers of PI 554419 with other Ae. uniaristata and Ae. comosa accessions as well as the taxonomic character of spike morphology. A disomic 1M/1D substitution line NB 4-8-5-9 derived from PI 554419 was identified from a distant hybridization of Ae. comosa with common wheat (STM 10/CSph1b//CM 39///13 P2-6) by the molecular cytological method. Furthermore, the agronomic and seed morphological traits, as well as the flour processing quality properties of NB 4-8-5-9, were compared with those of its three common wheat parents in two different locations during the 2017-2018 growing seasons. The agronomical traits of NB 4-8-5-9 were similar to or even better than its parents. The seed size-related traits of NB 4-8-5-9 were better than those of all three parents, and the 1000-grain weight and grain width were close to those of Chuanmai 39 (CM 39) and 13 P2-6 and larger than those of CSph1b. The processing quality properties of NB 4-8-5-9 were more similar to those of 13 P2-6 and CSph1b but less similar to those of CM 39. The 1M/1D substitution line NB 4-8-5-9 could further be used for developing translocation lines with 1M segment. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-021-01207-2.

Characterization of high- and low-molecular-weight glutenin subunits from Chinese Xinjiang wheat landraces and historical varieties.

Landraces and historical varieties are necessary germplasms for genetic improvement of modern cereals. Allelic variations at the Glu-1 and Glu-3 loci in 300 common wheat landraces and 43 historical varieties from Xinjiang, China, were evaluated by Sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and allele-specific molecular markers. Among the materials investigated, three, nine, and seven alleles were identified from the Glu-A1, Glu-B1, and Glu-D1 loci, respectively, and a total of 26 high-molecular-weight glutenin subunit (HMW-GS) combinations were found, of which 18 combinations were identified in landraces and historical varieties. Allelic frequency of HMW-GS combinations null, 7 + 8, 2 + 12 was found to be the highest in both the landraces (63.3%) and historical varieties (39.5%). Besides, some distinctive HMW-GS alleles, such as the novel Glu-B1 allele 6.1* + 8.1* and Glu-D1 alleles 2.6 + 12, 2.1 + 10.1, and 5** + 10 were observed in Xinjiang wheat landraces. Among the Glu-A3 and Glu-B3 loci of landraces and historical varieties, a total of eight and nine alleles were found, respectively. At each locus, two novel alleles were identified. A total of 33 low-molecular-weight glutenin subunit (LMW-GS) combinations of Glu-A3 and Glu-B3 were identified, with 31 and 14 combinations occurring in landraces and historical varieties, respectively, but only 10 combinations shared by both of them. As Glu-D1, Glu-A3, and Glu-B3 have highest contribution to the end-use quality and processing properties as compared to Glu-A1, Glu-B1, and Glu-D3 locus, the novel or distinctive HMW-GS and LMW-GS alleles in these loci could potentially be utilized for the improvement in the quality of modern wheat.

Analysis of Structural Genomic Diversity in Aegilops umbellulata, Ae. markgrafii, Ae. comosa, and Ae. uniaristata by Fluorescence In Situ Hybridization Karyotyping.

Fluorescence in situ hybridization karyotypes have been widely used for evolutionary analysis on chromosome organization and genetic/genomic diversity in the wheat alliance (tribe Triticeae of Poaceae). The karyotpic diversity of Aegilops umbellulata, Ae. markgrafii, Ae. comosa subsp. comosa and subsp. subventricosa, and Ae. uniaristata was evaluated by the fluorescence in situ hybridization (FISH) probes oligo-pSc119.2 and pTa71 in combination with (AAC)5, (ACT)7, and (CTT)12, respectively. Abundant intra- and interspecific genetic variation was discovered in Ae. umbellulata, Ae. markgrafii, and Ae. comosa, but not Ae. uniaristata. Chromosome 7 of Ae. umbellulata had more variants (six variants) than the other six U chromosomes (2-3 variants) as revealed by probes oligo-pSc119.2 and (AAC)5. Intraspecific variation in Ae. markgrafii and Ae. comosa was revealed by oligo-pSc119.2 in combination with (ACT)7 and (CTT)12, respectively. At least five variants were found in every chromosome of Ae. markgrafii and Ae. comosa, and up to 18, 10, and 15 variants were identified for chromosomes 2 of Ae. markgrafii, 4 of Ae. comosa subsp. comosa, and 6 of Ae. comosa subsp. subventricosa. The six Ae. uniaristata accessions showed identical FISH signal patterns. A large number of intra-specific polymorphic FISH signals were observed between the homologous chromosomes of Ae. markgrafii and Ae. comosa, especially chromosomes 1, 2, 4, and 7 of Ae. markgrafii, chromosome 4 of Ae. comosa subsp. comosa, and chromosome 6 of Ae. comosa subsp. subventricosa. Twelve Ae. comosa and 24 Ae. markgrafii accessions showed heteromorphism between homologous chromosomes. Additionally, a translocation between the short arms of chromosomes 1 and 7 of Ae. comosa PI 551038 was identified. The FISH karyotypes can be used to clearly identify the chromosome variations of each chromosome in these Aegilops species and also provide valuable information for understanding the evolutionary relationships and structural genomic variation among Aegilops species.

The genetic diversity of group-1 homoeologs and characterization of novel LMW-GS genes from Chinese Xinjiang winter wheat landraces (Triticum aestivum L.).

Group-1 homoelog genes in wheat genomes encode storage proteins and are the major determinants of wheat product properties. Consequently, understanding the genetic diversity of group-1 homoelogs and genes encoding storage proteins, especially the low-molecular-weight glutenins (LMW-GSs), within wheat landrace genomes is necessary to further improve the quality of modern wheat crops. The genetic diversity of group-1 homoelogs in 75 Xinjiang winter wheat landraces was evaluated by Diversity Arrays Technology (DArT) markers. These data were used to select 15 landraces for additional LMW-GS gene isolation. The genetic similarity coefficients among landraces were highly similar regardless if considering the diversity markers on 1A, 1B, and 1D chromosomes individually or using all of the markers together. These similarities were evinced by the generation of four similar cluster dendrograms that comprised 11-15 landrace groups, regardless of the dataset used to generate the dendrograms. A total of 105 LMW-GS sequences corresponding to 79 unique genes were identified overall by using primers designed to target Glu-A3 and Glu-B3 loci, and 54 mature proteins were predicted from the unique LMW-GS genes. Nine novel chimeric LMW-GS genes were also identified, of which, one was recombinant for -i/-m, one for -s/-m, and seven for -m/-m parent genes, respectively. Phylogenetic analysis separated all of the LMW-GSs into three clades that were supported by moderate bootstrap values (> 70%). The clades corresponded to LMW-GS genes primarily harboring different N-terminals. These results provide useful information for better understanding the evolutionary genetics of the important Glu-3 locus of wheat, and they also provide new novel gene targets that can potentially be exploited to improve wheat quality.

The Resurgence of Introgression Breeding, as Exemplified in Wheat Improvement.

Breeding progress in most crops has relied heavily on the exploitation of variation within the species' primary gene pool, a process which is destined to fail once the supply of novel variants has been exhausted. Accessing a crop's secondary gene pool, as represented by its wild relatives, has the potential to greatly expand the supply of usable genetic variation. The crop in which this approach has been most strongly championed is bread wheat (Triticum aestivum), a species which is particularly tolerant of the introduction of chromosomal segments of exotic origin thanks to the genetic buffering afforded by its polyploid status. While the process of introgression can be in itself cumbersome, a larger problem is that linkage drag and/or imperfect complementation frequently impose a yield and/or quality penalty, which explains the reluctance of breeders to introduce such materials into their breeding populations. Thanks to the development of novel strategies to induce introgression and of genomic tools to facilitate the selection of desirable genotypes, introgression breeding is returning as a mainstream activity, at least in wheat. Accessing variation present in progenitor species has even been able to drive genetic advance in grain yield. The current resurgence of interest in introgression breeding can be expected to result in an increased deployment of exotic genes in commercial wheat cultivars.

Development and characterization of Triticum turgidum - Aegilops comosa and T. turgidum - Ae. markgrafii amphidiploids.

Aegilops comosa and Ae. markgrafii are diploid progenitors of polyploidy species of Aegilops sharing M and C genomes, respectively. Transferring valuable genes/traits from Aegilops into wheat is an alternative strategy for wheat genetic improvement. The amphidiploids between diploid species of Aegilops and tetraploid wheat can act as bridges to overcome obstacles from direct hybridization and can be developed by the union of unreduced gametes. In this study, we developed seven Triticum turgidum - Ae. comosa and two T. turgidum - Ae. markgrafii amphidiploids. The unreduced gametes mechanisms, including first-division restitution (FDR) and single-division meiosis (SDM), were observed in triploid F1 hybrids of T. turgidum - Ae. comosa (STM) and T. turgidum - Ae. markgrafii (STC). Only FDR was observed in STC hybrids, whereas FDR or both FDR and SDM were detected in the STM hybrids. All seven pairs of M chromosomes of Ae. comosa and C chromosomes of Ae. markgrafii were distinguished by fluorescent in situ hybridization (FISH) probes pSc119.2 and pTa71 combinations with pTa-535 and (CTT)12/(ACT)7, respectively. Meanwhile, the chromosomes of tetraploid wheat and diploid Aegilops parents were distinguished by the same FISH probes. The amphidiploids possessed specific valuable traits such as multiple tillers, large seed size related traits, and stripe rust resistance that could be utilized in the genetic improvement of wheat.

Correction to: Identification and mapping of expressed genes associated with the 2DL QTL for fusarium head blight resistance in the wheat line Wuhan 1.

Following publication of the original article [1], we have been notified that some important information was omitted by the authors in the Copyright note. The Copyright note should read as below.

A breeding strategy targeting the secondary gene pool of bread wheat: introgression from a synthetic hexaploid wheat.

KEY MESSAGE: Introgressing one-eighth of synthetic hexaploid wheat genome through a double top-cross plus a two-phase selection is an effective strategy to develop high-yielding wheat varieties. The continued expansion of the world population and the likely onset of climate change combine to form a major crop breeding challenge. Genetic advances in most crop species to date have largely relied on recombination and reassortment within a relatively narrow gene pool. Here, we demonstrate an efficient wheat breeding strategy for improving yield potentials by introgression of multiple genomic regions of de novo synthesized wheat. The method relies on an initial double top-cross (DTC), in which one parent is synthetic hexaploid wheat (SHW), followed by a two-phase selection procedure. A genotypic analysis of three varieties (Shumai 580, Shumai 969 and Shumai 830) released from this program showed that each harbors a unique set of genomic regions inherited from the SHW parent. The first two varieties were generated from very small populations, whereas the third used a more conventional scale of selection since one of bread wheat parents was a pre-breeding material. The three varieties had remarkably enhanced yield potential compared to those developed by conventional breeding. A widely accepted consensus among crop breeders holds that introducing unadapted germplasm, such as landraces, as parents into a breeding program is a risky proposition, since the size of the breeding population required to overcome linkage drag becomes too daunting. However, the success of the proposed DTC strategy has demonstrated that novel variation harbored by SHWs can be accessed in a straightforward, effective manner. The strategy is in principle generalizable to any allopolyploid crop species where the identity of the progenitor species is known.

Identification and mapping of expressed genes associated with the 2DL QTL for fusarium head blight resistance in the wheat line Wuhan 1.

BACKGROUND: Fusarium head blight (FHB) is a problem of great concern in small grain cereals, especially wheat. A quantitative trait locus (QTL) for FHB resistance (FHB_SFI) located on the long arm of chromosome 2D in the spring wheat genotype Wuhan 1 is a resistance locus which has potential to improve the FHB resistance of bread wheat since it confers effective resistance to wheat breeding lines. Recently, differentially expressed genes (DEG) have been identified by comparing near isogenic lines (NIL) carrying the susceptible and resistant alleles for the 2DL QTL, using RNA-Seq. In the present study, we aimed to identify candidate genes located within the genetic interval for the 2DL QTL for FHB resistance, as assessed by single floret inoculation (FHB_SFI), and possibly contributing to it. RESULTS: Combining previous and additional bioinformatics analyses, 26 DEG that were located on chromosome arm 2DL were selected for further characterization of their expression profile by RT-qPCR. Seven of those DEG showed a consistent differential expression profile between either three pairs of near isogenic lines or other genotypes carrying the R and S alleles for the 2DL QTL for FHB resistance. UN25696, which was identified in previous expression work using microarray was also confirmed to have a differential expression pattern. Those eight candidate genes were further characterized in 85 lines of a double haploid mapping population derived from the cross Wuhan 1/Nyubai, the population where the 2DL QTL was originally identified. The expression QTL for gene Traes_2DL_179570792 overlapped completely with the mapping interval for the 2DL QTL for FHB_SFI while the expression QTL for UN25696 mapped near the QTL, but did not overlap with it. None of the other genes had a significant eQTL on chromosome 2DL. Higher expression of Traes_2DL_179570792 and UN25696 was associated with the resistant allele at that locus. CONCLUSIONS: Of the 26 DEG from the 2DL chromosome further characterized in this study, only two had an expression QTL located in or near the interval for the 2DL QTL. Traes_2DL_179570792 is the first expression marker identified as associated with the 2DL QTL.

Genome-Wide Association Study Reveals Novel Genomic Regions Associated With High Grain Protein Content in Wheat Lines Derived From Wild Emmer Wheat.

Grain protein content (GPC) and yield are of two important traits in wheat, but their negative correlation has hampered their simultaneous improvement in conventional breeding. Wild emmer wheat (Triticum turgidum ssp. dicoccoides) is an important genetic resource for wheat quality improvement. In this study, we report a genome-wide association study (GWAS) using 13116 DArT-seq markers to characterize GPC in 161 wheat lines derived from wild emmer. Using a general linear model, we identified 141 markers that were significantly associated with GPC, and grouped into 48 QTL regions. Using both general linear model and mixed linear model, we identified four significant markers that were grouped into two novel QTL regions on chromosomes 2BS (QGpc.cd1-2B.1) and 7BL (QGpc.cd1-7B.2). The two QTLs have no negative effects on thousand kernel weight (TKW) and should be useful for simultaneous improvement of GPC and TKW in wheat breeding. Searches of public databases revealed 61 putative candidate/flanking genes related to GPC. The putative proteins of interest were grouped in four main categories: enzymes, kinase proteins, metal transport-related proteins, and disease resistance proteins. The linked markers and associated candidate genes provide essential information for cloning genes related to high GPC and performing marker-assisted breeding in wheat.