Wheat Breeding Programs Research Articles

Development, identification, and utilization of wheat-tetraploid Thinopyrum elongatum 4EL translocation lines resistant to stripe rust.

The new stripe rust resistance gene Yr4EL in tetraploid Th. elongatum was identified and transferred into common wheat via 4EL translocation lines. Tetraploid Thinopyrum elongatum is a valuable genetic resource for improving the resistance of wheat to diseases such as stripe rust, powdery mildew, and Fusarium head blight. We previously reported that chromosome 4E of the 4E (4D) substitution line carries all-stage stripe rust resistance genes. To optimize the utility of these genes in wheat breeding programs, we developed translocation lines by inducing chromosomal structural changes through 60Co-γ irradiation and developing monosomic substitution lines. In total, 53 plants with different 4E chromosomal structural changes were identified. Three homozygous translocation lines (T4DS·4EL, T5AL·4EL, and T3BL·4EL) and an addition translocation line (T5DS·4EL) were confirmed by the genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), FISH-painting, and wheat 55K SNP array analyses. These four translocation lines, which contained chromosome arm 4EL, exhibited high stripe rust resistance. Thus, a resistance gene (tentatively named Yr4EL) was localized to the chromosome arm 4EL of tetraploid Th. elongatum. For the application of marker-assisted selection (MAS), 32 simple sequence repeat (SSR) markers were developed, showing specific amplification on the chromosome arm 4EL and co-segregation with Yr4EL. Furthermore, the 4DS·4EL line could be selected as a good pre-breeding line that better agronomic traits than other translocation lines. We transferred Yr4EL into three wheat cultivars SM482, CM42, and SM51, and their progenies were all resistant to stripe rust, which can be used in future wheat resistance breeding programs.

Identification of Sr67, a new gene for stem rust resistance in KU168-2 located close to the Sr13 locus in wheat

Key messageSr67 is a new stem rust resistance gene that represents a new resource for breeding stem rust resistant wheat cultivarsRe-appearance of stem rust disease, caused by the fungal pathogen Puccinia graminis f. sp. tritici (Pgt), in different parts of Europe emphasized the need to develop wheat varieties with effective resistance to local Pgt populations and exotic threats. A Kyoto University wheat (Triticum aestivum L.) accession KU168-2 was reported to carry good resistance to leaf and stem rust. To identify the genomic region associated with the KU168-2 stem rust resistance, a genetic study was conducted using a doubled haploid (DH) population from the cross RL6071 × KU168-2. The DH population was phenotyped with three Pgt races (TTKSK, TPMKC, and QTHSF) and genotyped using the Illumina 90 K wheat SNP array. Linkage mapping showed the resistance to all three Pgt races was conferred by a single stem rust resistance (Sr) gene on chromosome arm 6AL, associated with Sr13. Presently, four Sr13 resistance alleles have been reported. Sr13 allele-specific KASP and STARP markers, and sequencing markers all showed null alleles in KU168-2. KU168-2 showed a unique combination of seedling infection types for five Pgt races (TTKSK, QTHSF, RCRSF, TMRTF, and TPMKC) compared to Sr13 alleles. The phenotypic uniqueness of the stem rust resistance gene in KU168-2 and null alleles for Sr13 allele-specific markers showed the resistance was conferred by a new gene, designated Sr67. Since Sr13 is less effective in hexaploid background, Sr67 will be a good source of stem rust resistance in bread wheat breeding programs.

TaeC: A manually annotated text dataset for trait and phenotype extraction and entity linking in wheat breeding literature.

Wheat varieties show a large diversity of traits and phenotypes. Linking them to genetic variability is essential for shorter and more efficient wheat breeding programs. A growing number of plant molecular information networks provide interlinked interoperable data to support the discovery of gene-phenotype interactions. A large body of scientific literature and observational data obtained in-field and under controlled conditions document wheat breeding experiments. The cross-referencing of this complementary information is essential. Text from databases and scientific publications has been identified early on as a relevant source of information. However, the wide variety of terms used to refer to traits and phenotype values makes it difficult to find and cross-reference the textual information, e.g. simple dictionary lookup methods miss relevant terms. Corpora with manually annotated examples are thus needed to evaluate and train textual information extraction methods. While several corpora contain annotations of human and animal phenotypes, no corpus is available for plant traits. This hinders the evaluation of text mining-based crop knowledge graphs (e.g. AgroLD, KnetMiner, WheatIS-FAIDARE) and limits the ability to train machine learning methods and improve the quality of information. The Triticum aestivum trait Corpus is a new gold standard for traits and phenotypes of wheat. It consists of 528 PubMed references that are fully annotated by trait, phenotype, and species. We address the interoperability challenge of crossing sparse assay data and publications by using the Wheat Trait and Phenotype Ontology to normalize trait mentions and the species taxonomy of the National Center for Biotechnology Information to normalize species. The paper describes the construction of the corpus. A study of the performance of state-of-the-art language models for both named entity recognition and linking tasks trained on the corpus shows that it is suitable for training and evaluation. This corpus is currently the most comprehensive manually annotated corpus for natural language processing studies on crop phenotype information from the literature.

Molecular and agro-morphological diversity assessment of some bread wheat genotypes and their crosses for drought tolerance.

Wheat, a staple cereal crop, faces challenges due to climate change and increasing global population. Maintaining genetic diversity is vital for developing drought-tolerant cultivars. This study evaluated the genetic diversity and drought response of five wheat cultivars and their corresponding F1 hybrids under well-watered and drought stress conditions. Molecular profiling using ISSR and SCoT-PCR markers revealed 28 polymorphic loci out of 76 amplified. A statistically significant impact of parental genotypes and their crosses was observed on all investigated agro-morphological traits, including root length, root weight, shoot length, shoot weight, proline content, spikelet number/spike, spike length, grain number/spike, and grain weight/spike. The parental genotypes P1 and P3 had desirable positive and significant general combining ability (GCA) effects for shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, shoot length, and root length under well-watered conditions, while P3 and P5 recorded the highest GCA estimates under drought stress. P3 and P4 showed the highest GCA effects for number of spikelets per spike, the number of grains per spike, and grain weight per spike under normal conditions. P5 presented the maximum GCA effects and proved to be the best combiner under drought stress conditions. The cross P1× P3 showed the highest positive specific combining ability (SCA) effects for shoot fresh weight under normal conditions, while P2×P3 excelled under water deficit conditions. P1× P2, P1 × P3, and P4× P5 were most effective for shoot dry weight under normal conditions, whereas P1×P3 and P3×P5 showed significant SCA effects under drought stress. Positive SCA effects for root fresh weight and shoot length were observed for P3×P5 under stressed conditions. Additionally, P4×P5 consistently recorded the highest SCA for root length in both environments, and P3×P5 excelled in the number of spikelets, grains per spike, and grain weight per spike under drought conditions. The evaluated genotypes were categorized based on their agronomic performance under drought stress into distinct groups ranging from drought-tolerant genotypes (group A) to drought-sensitive ones (group C). The genotypes P5, P2×P5, and P3×P5 were identified as promising genotypes to improve agronomic performance under water deficit conditions. The results demonstrated genetic variations for drought tolerance and highlighted the potential of ISSR and SCoT markers in wheat breeding programs for developing drought-tolerant cultivars.

Leveraging trait and QTL covariates to improve genomic prediction of resistance to Fusarium head blight in Central European winter wheat.

Fusarium head blight (FHB) is a devastating disease of wheat, causing yield losses, reduced grain quality, and mycotoxin contamination. Breeding can mitigate the severity of FHB epidemics, especially with genomics-assisted methods. The mechanisms underlying resistance to FHB in wheat have been extensively studied, including phenological traits and genome-wide markers associated with FHB severity. Here, we aimed to improve genomic prediction for FHB resistance across breeding programs by incorporating FHB-correlated traits and FHB-associated loci as model covariates. We combined phenotypic data on FHB severity, anthesis date, and plant height with genome-wide marker data from five Central European winter wheat breeding programs for genome-wide association studies (GWAS) and genomic prediction. Within all populations, FHB was correlated with anthesis date and/or plant height, and a marker linked to the semi-dwarfing locus Rht-D1 was detected with GWAS for FHB. Including the Rht-D1 marker, anthesis date, and/or plant height as covariates in genomic prediction modeling improved prediction accuracy not only within populations but also in cross-population scenarios.

Antioxidant and Secondary Metabolite Responses in Wheat under Cereal Leaf Beetle (Oulema melanopus L.) Infestation

AbstractWheat is one of the most important cereal crops grown in the Western Himalayas of India but its production is challenged by the insect “cereal leaf beetle (CLB)”. This study explores the impact of domestication and modern crop improvement on wheat's defense mechanisms against the CLB, a global threat to wheat cultivation. Sixteen diverse wheat genotypes having different ploidy levels were investigated, including wild wheat, landraces, mutants, advanced breeding lines, commercial varieties, and a Rye grass genotype. Genotypes with resistance genes, landraces, and wild wheat exhibited the lowest CLB infestation and oxidative damage. These genotypes displayed enhanced antioxidant enzyme activity, such as peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), and polyphenol oxidase (PPO), reduced reactive oxygen species (ROS) production, and increased plant secondary metabolite (phenol and tannin) production upon CLB infestation. Resistant durum wheat demonstrated moderate responses and exhibited higher levels of flavonoid production. On the other hand, susceptible durum wheat genotypes, commercial variety Shalimar Wheat‐02 (SW‐2), showed high CLB infestation, ROS production, reduced antioxidant enzyme and secondary metabolite production. This may be because modern varieties like SW‐2 were not selected for insect resistance. These findings emphasize the significance of preserving genetic diversity from wild wheat and landraces to bolster wheat breeding programs against pests such as CLB. This study underscores the need to harness ancestral wheat lines to enhance insect pest resistance in modern wheat cultivars.

Demonstration the effectiveness of NDVI with GGE biplot model in determination of high yielding durum wheat (Triticum durum Desf.) genotypes

The use of spectral indices such as normalised difference vegetation index (NDVI) is becoming an important element in the evaluation of physiological traits in cereal crops. Determining the correlation between spectral readings taken at different phenological stages of wheat plants and grain yield (GY) is crucial. This study aimed to demonstrate the effectiveness of NDVI in combination with the GGE biplot model in identifying high yielding durum wheat genotypes. Field experiments were conducted in multiple environments and growth stages to evaluate the relationship between NDVI and grain yield (GY). Twenty-five durum wheat genotypes were tested for two years under rainfed and supplementary irrigation conditions using a split plot experimental design. The results showed significant positive correlations between NDVI and GY, especially at the generative stages under rain-fed conditions. In contrast, NDVI at the grain-filling stage showed a weaker relationship with GY under supplemental irrigation. Genotypes exhibiting high NDVI values up to the stem elongation stage tended to have lower grain yields, emphasizing the importance of considering growth stage dynamics. GGE biplot analysis provided visual information on genotype-trait relationships, helping to identify genotypes with consistent performance in different environments. This study highlights that NDVI can be used to predict yield potential and guide selection in durum wheat breeding programs and the GGE biplot model serves as a valuable tool for genotype evaluation and selection.

Aggressiveness of Xanthomonas translucens pv. undulosa Isolates and Differential Reaction Among Spring Wheat Varieties Under a Controlled Environment

Xanthomonas translucens pv. undulosa causes bacterial leaf streak (BLS) in wheat that can lead to up to 40% losses globally. Understanding the aggressiveness of isolates from different locations in a state may help in screening for BLS resistance in wheat-breeding programs for that area. A greenhouse study to determine the aggressiveness of 17 isolates collected from South Dakota on spring wheat cultivar SY-Rockford and differential reactions of 21 spring wheat varieties grown in South Dakota to BLS under greenhouse conditions was conducted in 2021 and 2022. To assess BLS severity, one randomly selected plant per pot was rated based on the percentage of leaf area with BLS symptoms. Significant differences among the bacterial isolates were observed, with Xtpvu21OC (23.33%) being the most aggressive in causing BLS in SY-Rockford. Spring wheat varieties MN Washburn (25.0%) and ND Frohberg (22.5%) were found to be the most susceptible to BLS. It is suggested that the most aggressive Xanthomonas translucens pv. undulosa isolate available to researchers in their region be used in screening varieties and lines for BLS resistance.

Wheat stripe mosaic virus from Brazil and South Africa evolved as distinct subpopulations with low genetic variability

AbstractWheat stripe mosaic virus (WhSMV) is the causal agent of soilborne wheat mosaic disease (SBWMD) in Brazil, which is a serious threat to wheat production in the southern part of the country. WhSMV also occurs in Paraguay and South Africa. The virus is soilborne, transmitted by Polymyxa graminis, and management strategies are mainly based on genetic resistance. Variation in the reaction (type and severity of symptoms) of cultivars has been reported depending on the region and/or year of cultivation, leading wheat breeding programmes to test their materials in several locations, which increases costs and is time‐consuming. One hypothesis is that this variation in symptoms is a result of the genetic variability of WhSMV. We assessed the genetic variability and population structure of WhSMV infecting wheat in Brazil and South Africa. In field experiments conducted in different locations in southern Brazil, a consistent reproducibility of symptoms was observed in a set of cultivars, and molecular analysis showed a low degree of genetic variability of the Brazilian viral population. The hypothesis that the variation in SBWMD symptoms in Brazil is due to genetic variability of the virus was thus rejected. Comparison of the Brazilian and South African WhSMV isolates indicated that they comprise distinct subpopulations and that the Brazilian subpopulation is more variable than the South African subpopulation. The lower genetic variability of the South African subpopulation suggests genetic stability or a recent emergence of WhSMV in that region.

Comparative transcriptomics of stem rust resistance in wheat NILs mediated by Sr24 rust resistance gene

Stem rust of wheat is a deleterious fungal disease across the globe causing severe yield losses. Although, many stem rust resistance genes (Sr) are being used in wheat breeding programs, new emerging stem rust pathotypes are a challenge to important Sr genes. In recent years, multiple studies on leaf and yellow rust molecular mechanism have been done, however, for stem rust such studies are lacking. Current study investigated stem rust induced response in the susceptible wheat genotype C306 and its Near Isogenic Line (NIL) for Sr24 gene, HW2004, using microarray analysis to understand the transcriptomic differences at different stages of infection. Results showed that HW2004 has higher basal levels of several important genes involved in pathogen detection, defence, and display early activation of multiple defence mechanisms. Further Gene Ontology (GO) and pathway analysis identified important genes responsible for pathogen detection, downstream signalling cascades and transcription factors (TFs) involved in activation and mediation of defence responses. Results suggest that generation of Reactive Oxygen Species (ROS), cytoskeletal rearrangement, activation of multiple hydrolases, and lipid metabolism mediated biosynthesis of certain secondary metabolites are collectively involved in Sr24-mediated defence in HW2004, in response to stem rust infection. Novel and unannotated, but highly responsive genes were also identified, which may also contribute towards resistance phenotype. Furthermore, certain DEGs also mapped close to the Sr24-linked marker on Thinopyrum elongatum translocated fragment on wheat 3E chromosome, which advocate further investigations for better insights of the Sr24-mediated stem rust resistance.

Hybrid Solvent Retention Capacity (SRC) to predict Australian soft wheat cookie quality

The Solvent Retention Capacity (SRC) method has been widely used in evaluating soft wheat quality elsewhere but not in Australia. This paper studies the potential of applying SRC to predict the Australian soft wheat quality in sugar snap cookies, which the Indonesian mills value. The cost-effective hybrid SRC method improves efficiency and repeatability in general by replacing the manual shaking mechanism with a programable multitube vortex shaker. The hybrid SRC method helps to reduce work health and safety risks by eliminating manual tube shaking steps. The collaborative laboratory study is conducted with two Indonesian mills and compared against SRC measured by the hybrid and automatic SRC methods. All SRC values measured using the hybrid SRC method are significantly correlated with those measured with manual and automatic SRC methods: SRC water (r = 0.8–1.0, p < 0.0001); sucrose (r = 0.9, p < 0.0001); sodium carbonate (r = 0.9, p < 0.0001); and lactic acid (r = 0.7–0.8, p < 0.01). Among the four SRC solvents, considering the SRC water is highly effective in discriminating hard and soft wheat, the high correlations between different laboratories, the relatively smaller standard deviation across laboratories and storage time and temperature at 22 °C and the significant correlation with cookie spread, it could be the best predictor of Australian soft wheat quality. Overall, the hybrid SRC method could be helpful in the Australian soft wheat breeding program, especially in the early-stage selection of soft wheat cultivars. The cookie spread negatively correlates with Rapid Viscosity Analyser peak viscosity (r = −0.8, p < 0.01), suggesting Australian soft wheat targets a lower pasting property for a better cookie performance. The SRC values of flour samples from four different soft wheat cultivars are affected by storage temperature at 22 °C and 32 °C over 12 months with inconsistent trends. The flour samples stored at various temperatures across 0, 1, 3, 6 and 12 moths, particularly those kept at a higher temperature, have more variability in their SRC values and higher uncertainty, which must be accounted for when comparing results between different laboratories. A standard SRC range will be established in collaboration with the Indonesian mills to categorise the Australian soft wheat quality suitable for the Indonesian market.

Molecular Genetic Diversity of Local and Exotic Durum Wheat Genotypes and Their Combining Ability for Agronomic Traits under Water Deficit and Well-Watered Conditions.

Water deficit poses significant environmental stress that adversely affects the growth and productivity of durum wheat. Moreover, projections of climate change suggest an increase in the frequency and severity of droughts, particularly in arid regions. Consequently, there is an urgent need to develop drought-tolerant and high-yielding genotypes to ensure sustained production and global food security in response to population growth. This study aimed to explore the genetic diversity among local and exotic durum wheat genotypes using simple sequence repeat (SSR) markers and, additionally, to explore the combining ability and agronomic performance of assessed durum wheat genotypes and their 28 F1 crosses under normal and drought stress conditions. The investigated SSRs highlighted and confirmed the high genetic variation among the evaluated parental durum wheat genotypes. These diverse eight parental genotypes were consequently used to develop 28 F1s through a diallel mating design. The parental durum genotypes and their developed 28 F1s were assessed under normal and drought stress conditions. The evaluated genotypes were analyzed for their general and specific combining abilities as well as heterosis for agronomic traits under both conditions. The local cultivar Bani-Suef-7 (P8) is maintained as an effective combiner for developing shortened genotypes and improving earliness. Moreover, the local cultivars Bani-Suef-5 (P7) and Bani-Suef-7 (P8) along with the exotic line W1520 (P6) demonstrated excellent general combining ability for improving grain yield and its components under drought stress conditions. Furthermore, valuable specific hybrid combinations, W988 × W994 (P1 × P2), W996 × W1518 (P3 × P5), W1011 × W1520 (P4 × P6), and Bani-Suef-5 × Bani-Suef-7 (P7 × P8), were identified for grain yield and its components under drought stress conditions. The assessed 36 genotypes were grouped according to tolerance indices into five clusters varying from highly drought-sensitive genotypes (group E) to highly drought-tolerant (group A). The genotypes in cluster A (two crosses) followed by thirteen crosses in cluster B displayed higher drought tolerance compared to the other crosses and their parental genotypes. Subsequently, these hybrids could be considered valuable candidates in future durum wheat breeding programs to develop desired segregants under water-deficit conditions. Strong positive relationships were observed between grain yield and number of grains per spike, plant height, and 1000-grain weight under water-deficit conditions. These results highlight the significance of these traits for indirect selection under drought stress conditions, particularly in the early stages of breeding, owing to their convenient measurability.

Analysis of Genetic Architecture for Ten Genotypes of Bread Wheat Using Half Diallel Crosses Under Nitrogen Stress

This study included 10 genotypes of bread wheat are M45, Yakora, Giza168, Sids 12, SK95, Misr2, Giemiza 9, Sahel 1, Sids14, and Silano. The genotypes (parents and F1 crosses) were cultivated at the research station of the Department of Field Crops of the College of Agriculture at the University of Kirkuk, during the season (2021-2022) in two separate experiments on sufficiency and insufficiency of the nitrogen element using a Randomized Complete Block Design (R.C.B.D) and with three replications, to estimate the general and specific combining ability, gene action and some genetic parameters. The results of the statistical and genetic analysis showed that there are highly significant differences for the general and specific combining ability values and that the ratio of the combining ability variance components to the specific combining ability variance components was less than the one for nitrogen sufficiency and insufficiency for all the studied traits. Sids14 variety excelled in its desirable effects of general combining ability, followed by Sr. (Sids12). The hybrid (M45 × Sids14) had the highest desired values for the effects of the special combining ability at nitrogen levels for all the traits studied, followed by the cross (Sahel 1 × Sids 12) also for all the traits studied except for The number of spikes plant-1 when there was insufficient nitrogen. The heritability broad sense was high with sufficient and insufficient nitrogen, while heritability narrow sense was high with sufficient nitrogen in the number of grains spike-1 and grains yield plant-1 (gm) and medium in The number of spikes plant-1 and the weight 1000 grains (gm) and the biological yield in the insufficient amount of the nitrogen element, the heritability narrow sense was medium in all studied traits. The average degree of dominance was greater than one when nitrogen was sufficient and insufficient, which indicates the existence of Over dominance, and the expected genetic advance as a percentage was low except for the number of grains spike-1 when nitrogen was sufficient and the grains yield plant-1 (gm) when nitrogen was insufficient, as it was medium. (11.908 and 12.250), respectively, these parents that are superior in the general combining ability with high phenotypic significance can be included in wheat breeding programs to produce hybrids that are superior in the specific combining ability that can be invested in the following generations with in the breeding programs to reach the best promising varieties with future nitrogen insufficiency.

A platform for whole-genome speed introgression from Aegilops tauschii to wheat for breeding future crops.

Breeding new and sustainable crop cultivars of high yields and desirable traits has been a major challenge for ensuring food security for the growing global human population. For polyploid crops such as wheat, introducing genetic variation from wild relatives of its subgenomes is a key strategy to improve the quality of their breeding pools. Over the past decades, considerable progress has been made in speed breeding, genome sequencing, high-throughput phenotyping and genomics-assisted breeding, which now allows us to realize whole-genome introgression from wild relatives to modern crops. Here, we present a standardized protocol to rapidly introgress the entire genome of Aegilops tauschii, the progenitor of the D subgenome of bread wheat, into elite wheat backgrounds. This protocol integrates multiple modern high-throughput technologies and includes three major phases: development of synthetic octaploid wheat, generation of hexaploid A. tauschii-wheat introgression lines (A-WIs) and homozygosis of the generated A-WIs. Our approach readily generates stable introgression lines in 2 y, thus greatly accelerating the generation of A-WIs and the introduction of desirable genes from A. tauschii to wheat cultivars. These A-WIs are valuable for wheat-breeding programs and functional gene discovery. The current protocol can be easily modified and used for introgressing the genomes of wild relatives to other polyploid crops.

Phenotypic response of a core collection of Aegilops triuncialis accessions to wheat leaf rust and expression pattern of genes involved in resistance

AbstractLeaf rust caused by Puccinia triticina Eriks. is a serious threat to wheat production worldwide. Exploiting wild relatives can effectively help to improve the genetic resistance of wheat against rust. This study aimed to evaluate the responses of 34 Aegilops triuncialis accessions to seven Pt pathotypes and to analyse expression of genes associated with resistance at the seedling stage. Following multipathotype testing, two accessions with contrasting resistance were analysed at 0, 6, 12 and 24 h post‐inoculation for the expression profile of genes related to PR1, PR2, PR4, PR9, phenylalanine ammonia‐lyase and ATP‐binding cassette transporter. Of the accessions tested, eight showed high infection types of “3” to at least one Pt pathotype, while the remaining accessions had low ITs (“0;=” to “2+”) against all pathotypes. The relative expressions of all candidate genes increased at all‐time points, but the expression level in the incompatible interaction was significantly higher than that of the compatible. The close relationship between PR proteins, PAL, salicylic acid‐ and jasmonic acid‐responsive proteins, as well as the proteins involved in the production of reactive oxygen species and lignin, could point to the specific recognition of the pathogen followed by the timely and intense induction of the expression of PR genes as the main reasons for resistance in incompatible interaction. In conclusion, the present study identified potentially new sources of resistance in this Ae. triuncialis population, which can be exploited in wheat breeding programs.

Genetic analysis of yield related traits in 5×5 diallel crosses of spring wheat (Triticum aestivum L.)

Wheat, a staple crop and an essential component of global food security, holds immense significance for Pakistan due to its historical roots, agricultural contributions, and socio-economic impact. The present study was conducted to reveal the genetics of various yield associated traits in spring wheat using 5 × 5 diallel cross scheme involving high yielding wheat varieties. A total of ten tillers per plant, 1000-grain weight, number of total grains per spike, peduncle length, length of spike, and yield of grain per plant were among the characteristics that were evaluated. Hybrid vigor can be a viable strategy for further improving these characteristics, as the graphical analysis for all characteristics per plant demonstrated supremacy form of gene activity. While additive action of gene with partial dominance dictated the transmission of peduncle length and number of tillers per plant, these features might be improved in early generations by selecting for attractive transgressive segregates. For all of the studied characteristics no epistasis was evaluated. This study is promising and has the potential to significantly impact wheat breeding programs, agricultural productivity, and food security in the coming years.

Paternally imprinted LATE-FLOWERING2 transcription factor contributes to paternal-excess interploidy hybridization barriers in wheat.

Interploidy hybridization between hexaploid and tetraploid genotypes occurred repeatedly during genomic introgression events throughout wheat evolution, and is commonly employed in wheat breeding programs. Hexaploid wheat usually serves as maternal parent because the reciprocal cross generates progeny with severe defects and poor seed germination, but the underlying mechanism is poorly understood. Here, we performed detailed analysis of phenotypic variation in endosperm between two interploidy reciprocal crosses arising from tetraploid (Triticum durum, AABB) and hexaploid wheat (Triticum aestivum, AABBDD). In the paternal- versus the maternal-excess cross, the timing of endosperm cellularization was delayed and starch granule accumulation in the endosperm was repressed, causing reduced germination percentage. The expression profiles of genes involved in nutrient metabolism differed strongly between these endosperm types. Furthermore, expression patterns of parental alleles were dramatically disturbed in interploidy versus intraploidy crosses, leading to increased number of imprinted genes. The endosperm-specific TaLFL2 showed a paternally imprinted expression pattern in interploidy crosses partially due to allele-specific DNA methylation. Paternal TaLFL2 binds to and represses a nutrient accumulation regulator TaNAC019, leading to reduced storage protein and starch accumulation during endosperm development in paternal-excess cross, as confirmed by interploidy crosses between tetraploid wild-type and clustered regularly interspaced palindromic repeats (CRISPR) - CRISPR-associated protein 9 generated hexaploid mutants. These findings reveal a contribution of genomic imprinting to paternal-excess interploidy hybridization barriers during wheat evolution history and explains why experienced breeders preferentially exploit maternal-excess interploidy crosses in wheat breeding programs.

Mineral contents and antioxidant activities of Karakılçık durum wheat (Triticum turgidum subsp. durum (Desf.) Husn.) genotypes

The importance of antioxidants and minerals in food has increased with the growing awareness of consumers in recent years. Türkiye is rich in genetic diversity for wheat as it is located at the intersection of three floristic regions and is part of the Fertile Crescent. In this study, the antioxidant activity of Karakılçık durum wheat (Triticum turgidum subsp. durum (Desf.) Husn.) populations from 12 different regions of Türkiye was determined using the DPPH method. In addition, the contents of mineral nutrients (Ca, Cu, Fe, Mg, Mn, Zn) were determined in an ICP-OES device with milled wheat. Karakılçık genotypes were sowed in a field using an augmented trial design consisting of five rows and six blocks, with each block containing five control varieties. The result of the study was that the landrace Karakılçık genotypes exhibited antioxidant activity varying between 14.7-40.2 μmol TE g-1. The Ca contents of landrace Karakılçık genotypes varied between 13.0-249.9 ppm, Cu contents 0.6-22.7 ppm, Fe contents 28.7-93.9 ppm, Mg contents 583.7-1194.0 ppm, Mn contents 31.4-87.7 ppm, and Zn contents 22.3-68.5 ppm. The results of the study reveal that Karakılçık landrace genotypes have large differences in antioxidant and mineral content, that these differences have the potential to be used in wheat breeding programs, and that wheat flour obtained from Karakılçık landrace genotypes is important.

HaploCatcher: An R package for prediction of haplotypes.

Wheat (Triticum aestivum L.) is crucial to global food security but is often threatened by diseases, pests, and environmental stresses. Wheat-stem sawfly (Cephus cinctus Norton) poses a major threat to food security in the United States, and solid-stem varieties, which carry the stem-solidness locus (Sst1), are the main source of genetic resistance against sawfly. Marker-assisted selection uses molecular markers to identify lines possessing beneficial haplotypes, like that of the Sst1 locus. In this study, an R package titled "HaploCatcher" was developed to predict specific haplotypes of interest in genome-wide genotyped lines. A training population of 1056 lines genotyped for the Sst1 locus, known to confer stem solidness, and genome-wide markers was curated to make predictions of the Sst1 haplotypes for 292 lines from the Colorado State University wheat breeding program. Predicted Sst1 haplotypes were compared to marker-derived haplotypes. Our results indicated that the training set was substantially predictive, with kappa scores of 0.83 for k-nearest neighbors and 0.88 for random forest models. Forward validation on newly developed breeding lines demonstrated that a random forest model, trained on the total available training data, had comparable accuracy between forward and cross-validation. Estimated group means of lines classified by haplotypes from PCR-derived markers and predictive modeling did not significantly differ. The HaploCatcher package is freely available and may be utilized by breeding programs, using their own training populations, to predict haplotypes for whole-genome sequenced early generation material.

Identification of a Novel Pm65 Allele Conferring a Wide Spectrum of Resistance to Powdery Mildew in Wheat Accession PI 351817.

Powdery mildew is caused by the highly adaptive biotrophic fungus Blumeria graminis f. sp. tritici infecting wheat worldwide. Novel powdery mildew resistance genes are urgently needed that can be used rapidly in wheat cultivar development with minimal disruption of trait advances elsewhere. PI 351817 is a German cultivar exhibiting a wide spectrum of resistance to B. graminis f. sp. tritici isolates collected from different wheat-growing regions of the United States. Evaluation of an F2 population and 237 F2:3 lines derived from OK1059060-2C14 × PI 351817 for responses to B. graminis f. sp. tritici isolate OKS(14)-B-3-1 identified a single dominant gene, designated Pm351817, for powdery mildew resistance in PI 351817. Using bulked segregant analysis (BSA) and simple sequence repeat (SSR) markers, Pm351817 was mapped in the terminal region of the long arm of chromosome 2A. Deep sequencing of the genotyping-by-sequencing libraries of the two parental lines identified a set of single-nucleotide polymorphism (SNP) markers in the 2AL candidate gene region. Those SNP markers was subsequently converted to Kompetitive allele-specific PCR (KASP) markers for genotyping the mapping population. Linkage analysis delimited Pm351817 to a 634-kb interval between Stars-KASP656 (771,207,512 bp) and Stars-KASP662 (771,841,609 bp) on 2AL, based on the Chinese Spring reference sequence IWGSC RefSeq v 2.1. Tests of allelism indicated that Pm351817 is located at the Pm65 locus. Pm351817 shows resistance to all B. graminis f. sp. tritici isolates used in this study and can be used to enhance powdery mildew resistance in the United States. KASP markers flanking Pm351817 can be used to select Pm351817 in wheat breeding programs after further tests for polymorphism.