Molecular cytological analysis of alien introgressions in common wheat lines created by crossing of Triticum aestivum with T. dicoccoides and T. dicoccum.

Wild and domesticated emmer (ВВАА, 2n = 28) are of significant interest for expanding the genetic diversity of common wheat as sources of a high protein and microelement grain content, resistance to many biotic and abiotic factors. Particular interest in these species is also determined by their close relationship with Triticum aestivum L., which facilitates interspecific hybridization. The objective of this work was to analyze the nature of alien introgressions in hybrid lines from crossing common wheat varieties with T. dicoccoides and T. dicoccum, and to assess the effect of their genome fragments on the cytological stability of introgression lines. A C-banding technique and genotyping with SNP and SSR markers were used to determine localization and length of introgression fragments. Assessment of cytological stability was carried out on the basis of chromosome behavior in microsporogenesis. A molecular cytogenetic analysis of introgression wheat lines indicated that the inclusion of the genetic material of wild and domesticated emmer was carried out mainly in the form of whole arms or large fragments in the chromosomes of the B genome and less extended inserts in the A genome. At the same time, the highest frequency of introgressions of the emmer genome was observed in chromosomes 1A, 1B, 2B, and 3B. The analysis of the final stage of meiosis showed a high level of cytological stability in the vast majority of introgression wheat lines (meiotic index was 83.0-99.0 %), which ensures the formation of functional gametes in an amount sufficient for successful reproduction. These lines are of interest for the selection of promising material with agronomically valuable traits and their subsequent inclusion in the breeding process.

The HMA2 Gene Expression in Leaves of Introgressive Wheat Lines under Zn Optimum and Deficiency Content in Root Environment.

In two introgressive lines of bread wheat (15-7-1 and 15-7-2), which differ in the allelic status of the Gpc-B1 gene, the expression of the gene encoding the HMA2 transport protein in flag leaves under optimum Zn content in substrate (2 µÐœ) and in its deficiency (0 µÐœ) was investigated. This is the first study to show that the plants carrying functional allele of the Gpc-В1 gene (line 15-7-1) have a higher level of TaHMA2 transcripts than the plants with nonfunctional allele of the Gpc-В1 gene (line 15-7-2) both at optimum Zn content in substrate and at its deficiency. Importantly, the high TaHMA2 gene expression did not affect the wheat shoot growth but correlated with a high Zn concentration in the aboveground part of plants. It is assumed that the NAC transcription factor encoded by the Gpc-В1 gene may be involved in the regulation of the ТаНМА2 gene expression.

[Preferential elimination of chromosome 5R of rye in the progeny of 5R5D dimonosomics].

Transmission of chromosome 5R of rye (Secale cereale L.) and chromosome 5D of common wheat (Triticum aestivum L.) through gametes of 5R5D dimonosomics (2n = 42, 20W" + 5R' + 5D') was studied. Chromosome 5R was found to have lower competitiveness as compared to 5D. Gametes with the rye chromosome were two times less often involved in the formation of a progeny. The combined frequency of the karyotypes of wheat (5D5D) and wheat monosomics (5D) was 11.6-fold higher than the frequency of the karyotypes of substitution lines (5R5R) and monosomics for the rye chromosome (5R). The karyotypes of 10.38% of hybrid plants had aberrant 5R chromosomes with different translocations formed as a result of breakages in the centromere and in the proximal region of the long arm. Telocentrics for the short arm (t5RS), i5RS isochromosomes, and chromosomes with a terminal deletion T5RS.5RL-del were identified. The absence of amplification of SSR markers mapped on 5RS and the detection of PCR products for a number of 5RL markers (ineluding the genome-specific rye marker Xrms115) permitted nine plants carrying only the long arm of chromosome 5R to be revealed. Since t5RL telocentrics were not detected by the cytological analysis, the results obtained allow us to suggest the presence of small intercalary translocations of the long arm of chromosome 5R in chromosome 5D or in other wheat chromosomes.

[Recombinant genome of cereals: the pattern of formation and the role in evolution of polyploid species].

The pivotal-differential model of evolution of polyploid species of cereals has been experimentally reproduced, and the pattern of the formation of a recombinant genome has been analyzed. It has been found that mutual substitution of chromosomes of the original genomes is subjected to selection pressure and, hence, is nonrandom. The selection occurs at the level of homeologs, whose selective advantages are determined by interactions between the genotype and the environment. If a homeolog has distinct selective advantages, the chromosomal composition of the corresponding homeologous group is completed rapidly, which leads to the formation of intergenomic recombination at the level of whole chromosomes. If homeologs have the same competitiveness, the composition of the group is stabilized more slowly. Domination of the genetic systems of the basic genome ensures a high rate of pairing of homeologous chromosomes of the recombinant genome during meiosis, which leads to recombinations at the level of chromosomal segments. It has been demonstrated that different combinations of chromosomes from original genomes are selected at different conditions of plant growth.

[Production of wheat-rye substitution lines based on winter rye cultivars with karyotype identification by means of C-banding, GISH, and SSR markers].

The study presents a continuation of the research aimed at producing of wheat-rye substitution lines based on the cross (Triticum aestivum L. x Secale sereale L.) x Triticum aestivum L., and using winter rye cultivars Vyatka and Vietnamskaya Mestnaya. In BC1F5 two lines were identified, having karyotypes in which a pair of homologous wheat chromosomes was substituted by a homeologous pair of rye chromosomes. The chromosome composition of these lines was analyzed using C-banding, GISH, and SSR markers. It was demonstrated that karyotype of each line included a single pair of rye chromosomes and lacked wheat-rye translocations. The rye chromosomes were identified, and the chromosomes of wheat, at which the substitutions occurred, were determined. The lines generated by crosses with rye of Vyatka and Vietnamskaya Mestnaya cultivars were designated 1Rv(1A) and 5Rviet(5A), respectively. Chromosome identification and classification of the lines makes it possible to use them in breeding programs and genetic studies.

[Production of wheat-rye substitution lines and identification of chromosome composition of karyotypes using C-banding, GISH, and SSR markers].

Based on the cross (Triticum aestivum L. x Secale cereale L.) x T. aestivum L., wheat-rye substitution lines (2n = 42) were produced with karyotypes containing, instead of a pair of homologous wheat chromosomes, a homeologous pair of rye chromosomes. The chromosome composition of these lines was described by GISH and C-banding methods, and SSR analysis. The results of genomic in situ hybridization demonstrated that karyotype of these lines included one pair of rye chromosomes each and lacked wheat--rye translocations. C-banding and SSR markers were used to identify rye chromosomes and determine the wheat chromosomes at which the substitution occurred. The lines were designated 1R(1D), 2R(2D)2, 2R(2D)3, 3R(3B), 6R(6A)2. The chromosome composition of lines IR(1A), 2R(W)1, 5R(W), 5R(5A), and 6R(W)1, which were earlier obtained according to the same scheme for crossing, was characterized using methods of telocentric analysis, GISH, C-banding, and SSR analysis. These lines were identified as 1R(1A), 2R(2D)1, 5R(5D), 5R(5A), and 6R(6A)1, C-banding of chromosomes belonging to line 1R(1A) revealed the presence of two translocated chromosomes (3DS.3DL-del. and 4AL.W) during simultaneous amplification of SSR markers located on 3DL and 4AS arms. The "combined" long arm of the newly derived chromosome 4A is assumed to be formed from the long arm of chromosome 4AS itself and a deleted segment 3DL. All examined lines are cytologically stable, except for 3R(3B), which does not affect the stability of rye 3R chromosome transfer. Chromosome identification and classification of the lines will permit them to be models for genetic studies that can be used thereafter as promising "secondary gene pools" for the purpose of plant breeding.