Winter Wheat Lines Research Articles

Estimation of the development of androgenic dihaploid lines of winter wheat of the R1 generation in vivo

Development of dihaploid lines using biotechnological methods can reduce not only the time required to breed a new variety, but also labor costs and technical resources. Earlier in our studies, there has been obtained seed material of androgenic dihaploid of the regenerated plants of the R0 generation, grown ex vitro. The next stage of the work delt with sowing the seeds of these plants in vivo. The purpose of the current study was to estimate the development of winter wheat plants of androgenic dihaploid lines of the R1 generation and parental varieties in vivo according to such characteristics as a length of phenophases, a vegetation period, morphometric estimation for comparison with each other and with parental genotypes, as well as for seed propagation. As a result of the study carried out in 2022–2024, there has been estimated a new nitial material of winter common wheat obtained on the basis of previously conducted biotechnological work. There have been studied androgenic dihaploid R1 lines according to the traits of vegetative and generative organs, for grain productivity of plants and seed germination. There have been selected promising lines for further breeding evaluation. Androgenic dihaploid lines of winter wheat of the R1 generation 79.1.5.1, 79.1.5.2, 79.2.1.1, 84.3.1.1, 84.3.3.1, 85.2.1.1 were the best according to vegetative, generative traits, grain productivity and seed germination. The best indicators of productivity and germination were characterized by androgenic dihaploid lines based on the hybrid ‘Rostovchanka 7 x Bezostaya 100’.

Physiological phenotyping of transpiration response to vapour pressure deficit in wheat

BackgroundPrecision phenotyping of short-term transpiration response to environmental conditions and transpiration patterns throughout wheat development enables a better understanding of specific trait compositions that lead to improved transpiration efficiency. Transpiration and related traits were evaluated in a set of 79 winter wheat lines using the custom-built “DroughtSpotter XXL” facility. The 120 l plant growth containers implemented in this phenotyping platform enable gravimetric quantification of water use in real-time under semi-controlled, yet field-like conditions across the entire crop life cycle.ResultsThe resulting high-resolution data enabled identification of significant developmental stage-specific variation for genotype rankings in transpiration efficiency. In addition, for all examined genotypes we identified the genotype-specific breakpoint in transpiration in response to increasing vapour pressure deficit, with breakpoints ranging between 2.75 and 4.1 kPa.ConclusionContinuous monitoring of transpiration efficiency and diurnal transpiration patterns enables identification of hidden, heritable genotypic variation for transpiration traits relevant for wheat under drought stress. Since the unique experimental setup mimics field-like growth conditions, the results of this study have good transferability to field conditions.

Androgenesis in vitro in anther culture of bread winter wheat

Aim. Study of the effectiveness of stages of in vitro androgenesis in anther culture for the creation of dihaploid lines of bread winter wheat. Methods. In vitro culture of isolated wheat anthers. For each genotype, the following parameters of androgenesis in vitro were determined: the percentage of caluses and the percentage of regeneration of green plants from the number of planted anthers; the percentage of acclimatized plants from regenerated green plantlets, as well as the percentage of fertile (doubled haploid) plants. Results. Androgenesis in vitro in the anther culture of 105 genotypes of soft winter wheat of different genetic origin was studied. Differences regarding the frequency of callusogenesis induction (from 0.17 to 21.25 percent of planted anthers) and the ability to regenerate plants (from 0 to 4.94 percent of planted anthers) were found. The dihaploid lines in anther culturefor almost 50 % of the studied genotypes were obtained. Spontaneous diploidization averaged 29.41 % of the obtained regenerants. Conclusions. Genotype-specific morphogenetic reactions of bread winter wheat microspores in the process of in vitro androgenesis were revealed. 122 dihaploid lines of bread winter wheat were obtained.

The influence of flowering periods on productivity characteristics in breeding samples of soft winter wheat created with the involvement of western european ecotypes

Aim. To determine the nature of the influence of flowering periods on productivity traits in soft winter wheat lines, which were created with the involvement of late-ripening samples of the Western European ecotype. Methods. Research methods are field, laboratory, selection-genetic, statistical. Results. The nature of the manifestation of the "date of flowering" trait in hybrids F1-F3 and selection numbers selected from hybrid populations with the participation of Western European ecotypes of soft winter wheat, the correlation dependence of the date of flowering, grain yield, ear length and the duration of the "flowering-maturity" period were established. Optimums for the manifestation of indicators that determined high yield and ear length were established. Conclusions. For each hybrid population created with the participation of parental components contrasting in duration of vegetation, it is necessary to develop a specific selection plan taking into account intra-population correlations of yield, flowering dates and the duration of the "flowering-maturity" period.

Registration of six albinism wheat sib lines for genetic aberration of photosynthetic pigments

AbstractPlant biologists have long been fascinated with the abnormal, the monstrous, and the defective. Six sib winter wheat (Triticum aestivum L.) lines with varying types of albinism, ShunMai GAG‐1 (Reg. no. GP‐1090, PI 704106), ShunMai GAG‐2 (Reg. no. GP‐1091, PI 704107), ShunMai GAG‐3 (Reg. no. GP‐1092, PI 704108), ShunMai GAG‐4 (Reg. no. GP‐1093, PI 704109), ShunMai GAG‐5 (Reg. no. GP‐1094, PI 704110), and ShunMai GAG‐6, (Reg. no. GP‐1095, PI 704111), were derived from a cross made in 2013 with unknown pedigree, and were developed using conventional phenotypic selections. Albinism, or stage‐specific albino, is their unique abnormal agronomic characteristics. All their leaves and tillers produced before winter are green, all their spring‐emerging leaves and tillers are albino, and all their summer‐producing leaves turn green again. Their main stems could have at least three albino leaves. In some colder springs, their after‐winter emerging leaves are reddish to pinkish. They may serve as useful experimental materials for addressing a wide range of wheat breeding problems, and for wheat field art too, and may also be important materials for functional studies and eventually lead to the gene discovery. We discuss the possible interactions between plastid genes and nuclear genes and between vernalization genes responsible for the transition from vegetative to generative growth stage and photosynthetic genes.

Comparative evaluation of the promising lines of winter soft wheat in the south of the Rostov region

The analysis of variability of winter soft wheat lines by quantitative traits is presented. The research was conducted in 2020–2023 in the Rostov region. Seven lines of winter soft wheat of the competitive variety trial were taken as an object of research. The Ermak variety was used as a standard. The yields of the lines during the years of study averaged from 9.78 to 10.12 t/ha with an average of 9.76 t/ha in the experiment. Plant height ranged from 85.0 to 115.0 cm. All the lines studied were classified as small- to medium-grained (32.9–45.9 g) in terms of 1000 grain weight. On average for the years of study, the minimum mass of 1000 grains was formed by the line 1638/19 (34.6 g), and the maximum – by the line 1361/19 (43.5 g). The lines had different groups of ripeness according to the indicator of the earing date. The spikelet length varied from 7.3 to 10.0 cm. The highest spikelet length was formed by the line 1361/19 (10.0 cm), the shortest – by the line 1120/19 (7.3 cm). The number of productive stems ranged from 471 to 924 stems/m2. The maximum number of productive stems for the years of the study was formed by the line 1921/20 (758 pcs./m2), the minimum – by the line 1361/19 (689 pcs./m2). The number of grains per plant ranged from 61.6 to 110.6. On average, the highest number of grains per plant was formed by the line 1638/19 (100.6 pcs.), the lowest – 1343/19 (70.4 pcs.). The grain weight per plant averaged 3.54 g and ranged from 2.26 to 4.56 g. The number of grains per ear varied from 28.9 to 51.5 pieces, the maximum number was formed by the lines 1361/19 (42.7 pcs.) and 1638/19 (41.2 pcs.). In terms of the grain weight per ear the standard was exceeded by the line 1361/19 (1.93 g), the values for the indicator varied from 1.02 to 2.28 g.

Identifying genomic regions associated with key agro‐morphological traits in soft red winter wheat using genome‐wide association study

AbstractAgro‐morphological traits play a significant role in the adaptation of wheat to diverse agroecosystems. Genetic understanding of these traits is crucial to develop cultivars adapted to specific environments and maximize their productivity. This is a comprehensive genome‐wide association study (GWAS) of 230 diverse lines of soft red winter wheat for identifying quantitative trait loci (QTLs) related to eight key agro‐morphological traits. The diversity panel was evaluated in two locations for three consecutive years (2020–2023). A total of 150 significant marker–trait associations were detected, including 65 for three flag leaf traits, 35 for peduncle length, 33 for plant height, 16 for heading date, and one for plant vigor using 27,466 single nucleotide polymorphism (SNP) markers. Eleven high‐confidence major‐effect QTLs explaining greater than 10% phenotypic variance were detected, of which seven were stable, and one showed an association with plant height and peduncle length. QTLs possibly allelic for important dwarfing (Rht23) and vernalization (Vrn‐B1) genes were identified. Six QTLs, QFlw.uga‐1A, QPdl.uga‐1A, QFlw.uga‐2B.2, QPdl.uga‐5A, QPdl.uga‐7A, and QPht.uga‐7B, are presumed to be novel, and nearby candidate gene(s) were identified for all except QPdl.uga‐1A. The pyramiding of favorable alleles from major‐effect QTLs was found to have significant improvement in peduncle length (shortened by 5 cm), flag leaf width (increased by 0.18 cm), and plant height (shortened by 11 cm). This study has improved our genetic understanding of important agro‐morphological traits. These results, upon further validation, can be used in breeding for desirable plant architecture to improve wheat yield potential.

Phytopathological screening of common winter wheat lines for resistance to Puccinia triticina

Abstract. Leaf rust on wheat caused by P. triticina is the most widespread fungal disease worldwide and in Bulgaria. The development of wheat genotypes resistant to leaf rust is related to the different types of resistance and ways of gene inheritance. The different varieties have different susceptibility during the different stages of their ontogenetic development. The study of the initial material is an important step in the breeding for resistance and it is an ongoing process. Two hundred and forty-six breeding lines were tested against the local population of P. triticina during 2015-2017, under conditions of infection field and in a greenhouse at Dobrudzha Agricultural Institute – General Toshevo, Bulgaria. Twenty lines were selected, which demonstrated different degrees of resistance under infection field conditions and which showed resistance to some of the seven pathotypes used in the study. The identification of the pathotypes was based on the type of reaction of 20 monogenic lines. The reaction of isogenic lines was compared with the reaction of the selection lines and the results showed that the reaction of line 165/05-46 corresponded to isogenic lines carrying genes Lr 9, Lr 19 and Lr 25. The response of the other 3 lines (245/03-72, 13/04-97, 14/06-110) partially coincided with the response of the above mentioned genes. The reaction of the other 3 lines (169/05-69, 14/06-81, 8/08-25) partially coincided with the reaction of isogenic lines carrying genes Lr 2a, Lr 28 and Lr 29. It was determined that seven of the lines were carriers of a race-specific gene and that it was necessary to subject these lines to further breeding and genetic studies to determine presence of race-specific resistance. Five of the lines (72/05-53, 61/03-75, 106/04-189, 268/03-151, 79/04-131) combined incomplete resistance at young stage with resistance at adult stage. Four of the tested lines (68/06-78, 29/02-133-38, 79/04-125-28, 197/05-33) exhibited typical race non-specific resistance or APR. Four lines (13/04-165, 14/05-119, 19/06-79 and 61/03-81) demonstrated “slow rusting” type of resistance. Twenty of the studied lines were carriers of effective resistance and can be included in the breeding programs as donors of resistance to P. triticina.

New Prospects for Improving Microspore Embryogenesis Induction in Highly Recalcitrant Winter Wheat Lines

Among various methods stimulating biological progress, double haploid (DH) technology, which utilizes the process of microspore embryogenesis (ME), is potentially the most effective. However, the process depends on complex interactions between many genetic, physiological and environmental variables, and in many cases, e.g., winter wheat, does not operate with the efficiency required for commercial use. Stress associated with low-temperature treatment, isolation and transfer to in vitro culture has been shown to disturb redox homeostasis and generate relatively high levels of reactive oxygen species (ROS), affecting microspore vitality. The aim of this study was to investigate whether controlled plant growth, specific tiller pre-treatment and culture conditions could improve the potential of microspores to cope with stress and effectively induce ME. To understand the mechanism of the stress response, hydrogen peroxide levels, total activity and the content of the most important low-molecular-weight antioxidants (glutathione and ascorbate), as well as the content of selected macro- (Mg, Ca, NA, K) and micronutrients (Mn, Zn, Fe, Cu, Mo) were determined. These analyses, combined with the cytological characteristics of the microspore suspensions, allowed us to demonstrate that an increased microspore vitality and stronger response to ME induction were associated with higher stress resistance based on more efficient ROS scavenging and nutrient management. It was shown that a modified procedure, combining a low temperature with mannitol and sodium selenate tiller pre-treatment, reduced oxidative stress and improved the effectiveness of ME in winter wheat lines.

Genetic Diversity and Genome-Wide Association Study for the Phenology Response of Winter Wheats of North America, Western Asia, and Europe

Wheat is a staple food in many areas around the World. In the 20th century, breeders and scientists were able to boost wheat yield considerably. However, a yield plateau has become a concern and is threatening food security. Investments in cutting-edge technologies, including genomics and precision phenology measurements, can provide valuable tools to drive crop improvement. The objectives of this study were to (i) investigate the genetic diversity in a set of winter wheat lines, (ii) characterize their phenological response under different vernalization and photoperiod conditions, and (iii) identify effective markers associated with the phenological traits. A total of 249 adapted genotypes of different geographical origin were genotyped using the 35K Axiom® Wheat Breeder’s Array. A total of 11,476 SNPs were used for genetic analysis. The set showed an average polymorphism information content of 0.37 and a genetic diversity of 0.43. A population structure analysis revealed three distinct subpopulations mainly related to their geographical origin (Europe, North America, and Western Asia). The lines of CGIAR origin showed the largest diversity and the lowest genetic distance to all other subpopulations. The phenology of the set was studied under controlled conditions using four combinations of long (19 h light) and short photoperiod (13 h light) and long vernalization (49 days at 5 °C) and no vernalization. With this, phenological traits such as earliness per se (Eps), relative response to vernalization (RRV), and relative response to photoperiod (RRP) were calculated. The phenotypic variation of growing degree days was significant in all phenology combinations. RRV ranged from 0 to 0.56, while RRP was higher with an overall average of 0.25. The GWAS analysis detected 30 marker-trait associations linked to five phenological traits. The highest significant marker was detected on chromosome 2D with a value of −log10(p) = 11.69. Only four loci known to regulate flowering exceeded the Bonferroni correction threshold of −log10(p) > 5.1. These results outline a solid foundation to address global food security and offer tremendous opportunities for advancing crop improvement strategies.

Root phenotyping and root water uptake calculation using soil water contents measured in a winter wheat field

Non-destructive phenotyping of roots and measurement of root water uptake from different soil layers in the field are vital for improving water management and facilitating the development of drought-resistant crop varieties, but difficult because of their opaqueness. As a result, indirect methods using easy-to-measure variables such as soil water content have been used as alternatives. However, the inherent measurement errors could undermine the robustness and reliability of these methods. This paper proposes a new method to bridge this knowledge gap by using soil water content profiles measured at two time points to calculate root uptake and root-length density. It is based on the Richards' equation by treating root uptake from different soil layers between the two time points as random unknown numbers; their distributions are calculated using the Bayesian framework, solved by the Markov Chain Monte Carlo method. We applied the method to 39 winter wheat lines grown in a silt-clay loam field. Soil water content profile measured at the first time point from each plot served as the initial condition, and water content measured at the second time point was the target to match the model for calculating average root water uptake and root-length density between the two time points. The results show that the measured soil water contents fall within the 95% confidence interval of the calculated soil water contents. The inherent soil water measurement errors lead to uncertainties in the calculated root water uptake for all lines, but such uncertainties decrease with soil depth. Although the soil types and agronomic management were the same for all 39 lines, their root water uptake from different soil layers varies considerably, with some lines more capable of using subsoil water than others. Generally, the calculated and measured root-length densities agree well, albeit the degree of the agreement varies with lines. While this paper focuses on methodology and applies the method to one growth stage spanning one month only, the consistent results for all 39 lines indicates the method is robust and can be applied to other crops cultivated in different conditions. Given the growing interest in improving root traits to enhance water use efficiency, the proposed method has important implications as phenotyping roots and understanding their water uptake from different soil layers in the field is a prerequisite to achieve this crucial target.

The use of weighted multiple linear regression to estimate QTL × QTL × QTL interaction effects of winter wheat (Triticum aestivum L.) doubled-haploid lines

Knowledge of the magnitude of gene effects and their interactions, their nature, and contribution to determining quantitative traits is very important in conducting an effective breeding program. In traditional breeding, information on the parameter related to additive gene effect and additive-additive interaction (epistasis) and higher-order additive interactions would be useful. Although commonly overlooked in studies, higher-order interactions have a significant impact on phenotypic traits. Failure to account for the effect of triplet interactions in quantitative genetics can significantly underestimate additive QTL effects. Understanding the genetic architecture of quantitative traits is a major challenge in the post-genomic era, especially for quantitative trait locus (QTL) effects, QTL–QTL interactions, and QTL–QTL–QTL interactions. This paper proposes using weighted multiple linear regression to estimate the effects of triple interaction (additive–additive–additive) quantitative trait loci (QTL–QTL–QTL). The material for the study consisted of 126 doubled haploid lines of winter wheat (Mandub × Begra cross). The lines were analyzed for 18 traits, including percentage of necrosis leaf area, percentage of leaf area covered by pycnidia, heading data, and height. The number of genes (the number of effective factors) was lower than the number of QTLs for nine traits, higher for four traits and equal for five traits. The number of triples for unweighted regression ranged from 0 to 9, while for weighted regression, it ranged from 0 to 13. The total aaagu effect ranged from − 14.74 to 15.61, while aaagw ranged from − 23.39 to 21.65. The number of detected threes using weighted regression was higher for two traits and lower for four traits. Forty-nine statistically significant threes of the additive-by-additive-by-additive interaction effects were observed. The QTL most frequently occurring in threes was 4407404 (9 times). The use of weighted regression improved (in absolute value) the assessment of QTL–QTL–QTL interaction effects compared to the assessment based on unweighted regression. The coefficients of determination for the weighted regression model were higher, ranging from 0.8 to 15.5%, than for the unweighted regression. Based on the results, it can be concluded that the QTL–QTL–QTL triple interaction had a significant effect on the expression of quantitative traits. The use of weighted multiple linear regression proved to be a useful statistical tool for estimating additive-additive-additive (aaa) interaction effects. The weighted regression also provided results closer to phenotypic evaluations than estimator values obtained using unweighted regression, which is closer to the true values.

Technological evaluation and determination of the traits stability in breeding materials in the early generations

The experiment was carried out on an experimental field of Institute of Plant Genetic Resources “K. Malkov”, Sadovo during the period 2016 - 2018. Nineteen common winter wheat lines and variety Sadovo 1 were studied, under the controlled trial conditions. The purpose of the research is technological evaluation and determination of the stability of traits in breeding materials in the early generations. The analyzes were carried out in a laboratory to assess the technological qualities of the grain. For the characterization of the studied lines, the following traits were taken into account: sedimentation value (SV) - using a 2% solution of glacial acetic acid (Pumpyanskiy, 1971); fermentation number FN - Pelshenke test (PT) by mixing a sample with live yeast in two repetitions (Pelshenke et al., 1953). The traits stability of breeding material was evaluated by the stability variances σi2 and Si2 according to Shukla (1972), the equivalency Wi according to Wricke (1962) and the criterion of phenotypic stability (Ysi) according to Kang (1993). The program product IPCSSVKYSI (Interactive program for calculating Shukla’s stability index (Ysi), developed by Kang & Magari (1995) was used to determine the stability index. The highest value for the trait sedimentation value was reported for line RU 32/2072.73.74, followed by line RU 47/3504. With a high value of the trait fermentation number are the lines RU 32/2072.73.74, RU 91/1729; RU 93/1895 and RU 128/2900. The influence of the factors genotype, environment and their interaction on the phenotypic appearance of the studied traits has been significant. The following lines can be highlighted as valuable breeding materials: RU 32/2072,73,74 and RU 47/3504 (high value and stability of the traits of sedimentation value and fermentation number). RU 49/2300 (high value and stability of the trait sedimentation value). RU 91/1729 (high value and stability of the trait fermentation number) The listed genotypes can be successfully used in breeding and improvement work to create new and high-quality common winter wheat varieties.

Phenomic versus genomic prediction—A comparison of prediction accuracies for grain yield in hard winter wheat lines

AbstractCommon bread wheat (Triticum aestivum L.) is a key component of global diets, but the genetic improvement of wheat is not keeping pace with the growing demands of the world's population. To increase efficiency and reduce costs, breeding programs are rapidly adopting the use of unoccupied aerial vehicles to conduct high‐throughput spectral analyses. This study examined the effectiveness of multispectral indices in predicting grain yield compared to genomic prediction. Multispectral data were collected on advanced generation yield nursery trials during the 2019–2021 growing seasons in the Colorado State University Wheat Breeding Program. Genome‐wide genotyping was performed on these advanced generations and all plots were harvested to measure grain yield. Two methods were used to predict grain yield: genomic estimated breeding values (GEBVs) generated by a genomic best linear unbiased prediction (gBLUP) model and phenomic phenotypic estimates (PPEs) using only spectral indices via multiple linear regression (MLR), k‐nearest neighbors (KNNs), and random forest (RF) models. In cross‐validation, PPEs produced by MLR, KNN, and RF models had higher prediction accuracy () than GEBVs produced by gBLUP ( ). In leave‐one‐year‐out forward validation using only multispectral data for 2020 and 2021, PPEs from MLR and KNN models had higher prediction accuracy of grain yield than GEBVs of those same lines. These findings suggest that a limited number of spectra may produce PPEs that are more accurate than or equivalently accurate as GEBVs derived from gBLUP, and this method should be evaluated in earlier development material where sequencing is not feasible.

Obtaining dihaploid lines of soft winter wheat with complex resistance to rust and hard smut by anther culture in vitro

Aim. Obtaining homozygous linear material of winter soft wheat of different genetic origin (complex hybrids), which are resistant to different types of rust by androgenesis in vitro. Methods. In vitro culture of isolated anthers of wheat. The percentage of callus and regeneration of green plants for each genotype calculated as a percentage of the planted anthers. Methods of phytopathological assessment of resistance to complex of various diseases. Results. The differences in the frequency of сallus induction (from 0.99 to 16.26 % of planted anthers) and the ability to regenerate plants (from 0 to 3.05 % of planted anthers) in the process of androgenesiss in vitro of winter soft wheat were detected. Fertile regenerants in the anthers culture 5 out of 9 studied hybrids have been obtained. The effectiveness of the last process was different: from 12.5 to 60.0 % (an average of 29.41 %) from the received regenerants. The high degree (8–9 points) of the resistance of the obtained dihaploids to a complex of diseases was shown. Conclusions. Genotype-specific of microspores morphogenetic reactions of soft winter wheat in the process of androgenesis in vitro were revealed. The highest level of callus formation were shown for samples 120/20 and 132/20. 15 dihaploid lines with complex rust resistance and hard smut were obtained.

Influence of alleles of the Ppd-D1 gene and different duration of requirement in yarovization on economic valuable signs of winter bread wheat

Aim. To determine the influence of alternative alleles of the Ppd-D1 gene and phenotypic differences in the duration of the need for vernalization and their interaction on earing time and grain yield of recombinant lines of bread winter wheat. Methods. Growing plants in the field and on the vegetation site, PCR with specific primers for Ppd-D1 and Ppd-B1c genes, phenological observations, artificial vernalization, statistical analysis. Results. 136 recombinant F7 lines from crossing [F1 (Chaika//Cappelle Desperez/2В Chinese Spring) / Kharkivska 81] F2 / Obryi identified by alleles of the Ppd-D1 gene, characterized by the duration of the need for vernalization, duration of the period to earing, plant height, weight 1000 grains and grain harvest. Conclusions. Genotypes with the presence of the Ppd-D1a allele eared 2.9 days earlier than those with the Ppd-B1b allele, and the lines with a 30-day need – one day earlier than those with a 40-day need for vernalization. Different combinations of alternative alleles of the Ppd-D1 gene and characteristics of the lines regarding the need for vernalization significantly influenced the differences in the duration of the period before heading and the weight of 1000 grains. Among the lines that significantly exceeded the control varieties Antonivka and Kuyalnik in terms of yield, those with a different combination of two traits were found, but the share of lines with a combination of the Ppd-D1a gene and 30 daily need for vernalization was greater and they formed the largest yield.

Resistance to Powdery Mildew Is Conferred by Different Genetic Loci at the Adult-Plant and Seedling Stages in Winter Wheat Line Tianmin 668.

Winter wheat line Tianmin 668 was crossed with susceptible cultivar Jingshuang 16 to develop 216 recombinant inbred lines (RILs) for dissecting its adult-plant resistance (APR) and all-stage resistance (ASR) against powdery mildew. The RIL population was genotyped on a 16K genotyping by target sequencing single-nucleotide polymorphism array and phenotyped in six field trials and in the greenhouse. Three loci-QPmtj.caas-2BL, QPmtj.caas-2AS, and QPmtj.caas-5AL-conferring APR to powdery mildew were detected on chromosomes 2BL, 2AS, and 5AL, respectively, of Tianmin 668. The effect of resistance to powdery mildew for QPmtj.caas-2BL was greater than that of the other two loci. A Kompetitive allele-specific PCR marker specific for QPmtj.caas-2BL was developed and verified on 402 wheat cultivars or breeding lines. Results of virulence and avirulence patterns to 17 Blumeria graminis f. sp. tritici isolates, bulked segregant analysis-RNA-sequencing, and a genetic linkage mapping identified a resistance allele at locus Pm4 in Tianmin 668 based on the seedling phenotypes of the RIL population. The PCR-based DNA sequence alignment and cosegregation of the functional marker with the phenotypes of the RIL population demonstrated that Pm4d was responsible for the ASR to isolate Bgt1 in Tianmin 668. The dissection of genetic loci for APR and ASR may facilitate the application of Tianmin 668 in developing powdery mildew-resistant wheat cultivars.

Genomic prediction with haplotype blocks in wheat.

Haplotype blocks might carry additional information compared to single SNPs and have therefore been suggested for use as independent variables in genomic prediction. Studies in different species resulted in more accurate predictions than with single SNPs in some traits but not in others. In addition, it remains unclear how the blocks should be built to obtain the greatest prediction accuracies. Our objective was to compare the results of genomic prediction with different types of haplotype blocks to prediction with single SNPs in 11 traits in winter wheat. We built haplotype blocks from marker data from 361 winter wheat lines based on linkage disequilibrium, fixed SNP numbers, fixed lengths in cM and with the R package HaploBlocker. We used these blocks together with data from single-year field trials in a cross-validation study for predictions with RR-BLUP, an alternative method (RMLA) that allows for heterogeneous marker variances, and GBLUP performed with the software GVCHAP. The greatest prediction accuracies for resistance scores for B. graminis, P. triticina, and F. graminearum were obtained with LD-based haplotype blocks while blocks with fixed marker numbers and fixed lengths in cM resulted in the greatest prediction accuracies for plant height. Prediction accuracies of haplotype blocks built with HaploBlocker were greater than those of the other methods for protein concentration and resistances scores for S. tritici, B. graminis, and P. striiformis. We hypothesize that the trait-dependence is caused by properties of the haplotype blocks that have overlapping and contrasting effects on the prediction accuracy. While they might be able to capture local epistatic effects and to detect ancestral relationships better than single SNPs, prediction accuracy might be reduced by unfavorable characteristics of the design matrices in the models that are due to their multi-allelic nature.

Genome-wide association mapping in elite winter wheat breeding for yield improvement

Increased grain yield (GY) is the primary breeding target of wheat breeders. We performed the genome-wide association study (GWAS) on 168 elite winter wheat lines from an ongoing breeding program to identify the main determinants of grain yield. Sequencing of Diversity Array Technology fragments (DArTseq) resulted in 19,350 single-nucleotide polymorphism (SNP) and presence-absence variation (PAV) markers. We identified 15 main genomic regions located in ten wheat chromosomes (1B, 2B, 2D, 3A, 3D, 5A, 5B, 6A, 6B, and 7B) that explained from 7.9 to 20.3% of the variation in grain yield and 13.3% of the yield stability. Loci identified in the reduced genepool are important for wheat improvement using marker-assisted selection. We found marker-trait associations between three genes involved in starch biosynthesis and grain yield. Two starch synthase genes (TraesCS2B03G1238800 and TraesCS2D03G1048800) and a sucrose synthase gene (TraesCS3D03G0024300) were found in regions of QGy.rut-2B.2, QGy.rut-2D.1, and QGy.rut-3D, respectively. These loci and other significantly associated SNP markers found in this study can be used for pyramiding favorable alleles in high-yielding varieties or to improve the accuracy of prediction in genomic selection.

Influence of agroclimatic conditions of the spring-summer vegetation on the formation of winter wheat yield under the needs of the forest-steppe of Western Siberia

Air temperature and moisture availability are the main environmental factors that have a significant impact on the development of plants during the growing season. The aim of this study is to study the relationship of yield and its constituent elements with climatic factors and to show their role in the formation of productivity of winter wheat. The research was carried out in 2009-2022 in the fields of the Siberian Research Institute of Plant Growing and Breeding, a branch of the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences. The research material was varieties and breeding lines of winter soft wheat of competitive variety testing. A positive dependence of the amount of precipitation and the hydrothermal coefficient in the interphase period “resumption of vegetation - trumpeting” with the duration of the growing season (r = 0.78; r = 0.73), productive tillering (r = 0.59; r = 0.64) was revealed, plant height (r = 0.60; r = 0.58), number of grains per plant (r = 0.66; r = 0.67). The correlation coefficient of productivity with the HTC and the amount of precipitation was r = 0.66 and r = 0.67, respectively, in the period of “booting - earing”. There is a significant negative correlation of resistance to lodging with both HTC and precipitation (r = -0.63; r = -0.56). The correlation coefficient of the HTC and the amount of rainfall with resistance to lodging in the interphase period “heading - wax ripeness” was significant (r = 0.55). HTC in the period “heading - wax ripeness” was directly proportional to the grain size index r = 0.60 and the amount of precipitation with a mass of 1000 grains r = 0.58. For the entire period of spring-summer vegetation, the correlation coefficient of the HTC and the amount of rainfall with the duration of the growing season was r = 0.63 and r = 0.65, respectively, with a height of r = 0.71 and r = 0.72, resistance to lodging r = -0.68 and r = -0.64 and overall bakery score r = -0.62 and r = -0.63. The amount of precipitation throughout the entire spring-summer vegetation has a positive effect on the grain weight per plant (r = 0.57). The sum of effective temperatures has a positive relationship with the nature of the grain in the period of “booting - heading” (r = 0.65). The correlation coefficient of the sum of effective temperatures with the amount of gluten in the period “heading - wax ripeness” r = 0.74 for the entire spring-summer vegetation r = 0.67.