High-molecular-weight glutenins play an important role in providing high baking qualities of bread wheat grain. However, breeding bread wheat for this trait is very laborious and, therefore, the genotyping of variety samples according to the allelic composition of high-molecular-weight glutenin genes is of great interest. The aim of the study was to determine the composition of high-molecular-weight glutenin subunits based on the identification of the allelic composition of the Glu-1 genes, as well as to identify the frequency of the Glu-1 alleles in bread wheat cultivars that are in breeding work under the conditions of the Pre-Ural steppe zone (PSZ). We analyzed 26 winter and 22 spring bread wheat varieties from the PSZ and 27 winter and 20 spring varieties from the VIR collection. Genotyping at the Glu-A1 locus showed that the Ax1 subunits are most common in winter varieties, while the predominance of the Ax2* subunits was typical of spring varieties and lines. In the Glu-B1 locus, the predominance of alleles associated with the production of the Bx7 and By9 subunits was revealed for both winter and spring varieties. In the case of the Glu-D1 gene, for all the wheat groups studied, the composition of the Dx5+Dy10 subunits was the most common: in 92.3 % of winter and 68.2 % of spring PSZ accessions and in 80 % of winter and 55 % of spring VIR accessions. The analysis of genotypes showed the presence of 13 different allelic combinations of the Glu-A1, Glu-B1, Glu-D1 genes in the PSZ varieties, and 19 combinations in the VIR varieties. The b b/al/с d allelic combination (Ax2* Вх7+Ву8/8*/9 Dx5+Dy10) turned out to be the most common for the PSZ spring varieties and lines, while for the PSZ winter accessions it was a с d (Ax1 Вх7+By9 Dx5+Dy10); the b с a and b с d genotypes (Ax2* Вх7+Ву9 Dx2+Dy12 and Ax2* Вх7+Ву9 Dx5+Dy10, respectively) occur with equal frequency among the VIR spring accessions; in the group of VIR winter varieties, the combination of the a b/   al d alleles (Ax1 Вх7+Ву8/8* Dx5+Dy10) prevails. The most preferred combination of alleles for baking qualities was found in the spring variety ‘Ekaterina’ and winter varieties ‘Tarasovskaya 97’, ‘Volzhskaya S3’, as well as in lines k-58164, L43510, L43709, L-67, L-83, which are recommended for further breeding programs to improve and preserve baking qualities in the conditions of the Pre-Ural steppe zone.

   Background. Bread wheat (Triticum aestivum L.) is one of the staple cereal crops, so it is of great interest to breeders and researchers and requires constant monitoring of existing cultivars, including the development of new ones through classical breeding and modern gene engineering. The key stage in these techniques is successful callusogenesis and organogenesis intarget objects. With this in view, the regeneration potential of two spring (‘Saratovskaya 55’ and ‘Sigma’) and three winter (‘Tanya’, ‘Fisht’ and ‘Pamyat’) cultivars of bread wheat was assessed, and optimal conditions were identified for callus induction and organogenesis using mature embryos.   Materials and methods. Immature and mature embryos of the five bread wheat cultivars were used in the study. The in vitro morphogenetic potential was evaluated under the impact of abiotic factors: preliminary exposure of grains to cold and use of exogenous hormones (2,4-D in various concentrations). Pretreatment of wheat with cold was carried out as follows: sterilized grains were incubated on the hormonal medium at a temperature of 4 °C for 2 weeks, and then transferred to 26 °C for 4 more weeks. The efficiency of callusogenesis and rhizogenesis was assessed and the numbers of morphogenetic calluses, regenerated and acclimatized plants were calculated.   Results and conclusions. The analysis made it possible to identify the bread wheat cultivars ‘Fisht’ and ‘Sigma’ for their high morphogenetic and regenerative potential. It was also shown that exposure to cold can serve as a good stimulating factor for producing a large number of calluses, but regenerants are better induced under normal conditions. The results also depended on the concentration of hormones applied. Universal conditions for morphogenesis and regeneration were not identified.

One of the problems of cereal biotechnology is the low efficiency of genetic transformation. The process of creating transgenic plants consists of three stages: transfer of foreign genetic material into the plant genome; obtaining of regenerated plants; selection of transgenic plants. Each stage is important and requires well-developed techniques. A widely used method of making transgenic plant is selection by including a selective antibiotic or herbicide resistance gene in DNA constructs. Effective breeding of transgenic plants requires knowledge of the exact concentrations and exposure duration of selective agents for the specific tissue culture species used. Our study aimed to identify the optimal concentration and exposure duration to glufosinate ammonium (Basta®) for the selection of resistant regenerates of bread wheat in vitro. Several options for the selection of resistant shoots were proposed based on the study results: induction of shoot regeneration on medium with 7.5 mg/L of glufosinate ammonium for 7 days after callus formation in the immature embryos culture on medium with Basta (concentration of at least 7.5 mg/L); constant cultivation of explants on media with glufosinate ammonium (minimum concentration—5 mg/L), when working with the culture of mature embryos on maternal grains; selection at the organogenesis stage should be carried out on the media with glufosinate ammonium concentration of 15 mg/L for 14 days or 10 mg/L for 28 days. The results of the work represent a significant contribution to accelerating work in the field of genetic and genomic studies of bread wheat—an important agricultural crop.

Studies of the genetic base and polymorphism of bread wheat cultivars aimed at identifying alleles of genes associated with high baking and other economically valuable traits seem to be relevant, since bread wheat, along with all representatives of the Triticeae tribe, has a huge genetic potential for creating cultivars with high technological and rheological properties of grain flour. The aim of this study was sequencing and analysis of the nucleotide sequences of the Glu-B1-1 gene, and analysis of the predicted amino acid sequences of its protein product in three cultivars of bread wheat. Thus, in the course of genotyping cultivars and lines of bread wheat for the Glu-B1-1 gene, in the cultivars ‘Avesta’, ‘Leningradka krupnozernaya’ and line C-75094, previously undescribed changes in the size of amplifiable regions of the Glu-B1-1 gene for high-molecular-weight glutenins were found. Comparative analysis of the nucleotide sequences of these genes with known sequences showed the presence of two deletions in ‘Avesta’ and C-75094 and the presence of seven single-nucleotide substitutions in ‘Leningradka krupnozernaya’. Alignment of the predicted Glu-B1 amino acid sequences of the studied accessions and the standard cultivar carrying the Glu-B1-a allele showed that deletions in the amino acid sequences of ‘Avesta’ and C-75094 accessions are localized in the central domain of the protein and affect the amount of tri-, hexa-, and nonapeptides, and in ‘Leningradka krupnozernaya’, a decrease in GQQ and PGQGQQ by one unit was revealed. In addition, substitutions of five amino acids were found in ‘Leningradka krupnozernaya’. Thus, we have found previously undescribed deletions and substitutions in the nucleotide sequences of the Glu-B1-1 gene for high-molecular-weight glutenins, which lead to changes in amino acid sequences in functionally important regions, namely, in the central domains of protein molecules. The identified mutations can be used for genotyping bread wheat cultivars.