<h4>Background</h4>Triticum kiharae (A^tA^tGGDD, 2n = 42) is of interest for the improvement of bread wheat as a source of high grain protein and gluten content, as well as resistance to many diseases. The use of T. kiharae for the improvement of T. aestivum L. is complicated by the fact that the homology degree of their genomes is low and this leads to an unbalanced set of chromosomes in the gametes of its first generations and the elimination of some genotypes. The aim of this study was to analyze the nature of alien introgressions and their effect on the cytological stability of hybrids obtained from crossing of bread wheat varieties with T. kiharae.<h4>Results</h4>Using C-banding, the presence of entire chromosomes of T. kiharae in the karyotypes of hybrid lines (intergenomic substitution 2G/2B), chromosome arms (centric translocation Т2A^tS:2AL) and large inserts in the form of terminal translocations involving chromosomes of 1st, 3rd and 5th homoeologous groups of B- and G-genomes were found. Molecular markers revealed short introgression of T. kiharae into the genome of common wheat varieties. The highest introgression frequency was shown for 1A, 1B, 2A, 5B, and 6A chromosomes, while no foreign chromatin was detected in 4A and 4B chromosomes. A high level of cytological stability (a meiotic index of 88.18-93.0%) was noted for the majority of introgression lines. An exception was found for the lines containing the structural reorganization of chromosome 5B, affecting the main genes of chromosome synapsis in terms of their functioning.<h4>Conclusions</h4>During the stabilization of hybrid karyotypes, the introgression of genetic material from T. kiharae into the genome of T. aestivum occurs in the form of short fragments detectable only by molecular markers and in the form of whole chromosomes (intergenomic substitution) and their large fragments (centric and terminal translocations). The level of cytological stability achieved in Results Using C-banding, the presence of entire chromosomes of T. kiharae in the karyotypes of hybrid lines (intergenomic substitution 2G/2B), chromosome arms (centric translocation Т2A t S:2AL) and large inserts in the form of terminal translocations involving chromosomes of 1st, 3rd and 5th homoeologous groups of B- and G-genomes were found. Molecular markers revealed short introgression of T. kiharae into the genome of common wheat varieties. The highest introgression frequency was shown for 1A, 1B, 2A, 5B, and 6A chromosomes, while no foreign chromatin was detected in 4A and 4B chromosomes. One of the main methods used for the localization of alien introgression is C-banding, which allows to detect the substitution of chromosomes or their arms, as well as extended translocations and large deletions [ 6 ] according to the pattern of the eu- and heterochromatin blocks in each chromosome. However, many cereal genomes contain a small amount of heterochromatin, which limits the use of this method. With the construction of saturated molecular genetic maps of bread wheat and other cereal species, it became possible to use molecular markers to detect structural changes in low-heterochromatic genomes and identify short introgression fragments. For the molecular cytogenetic analysis, we used seven hybrid lines selected on the basis of inheritance of morphological characteristics and productivity in generations F 4 - F 9 . C-banding As already noted, the C-banding technique effectiveness directly depends on the saturation of a differential staining pattern of chromosomes, within which structural transformations are analyzed. If these reorganizations occur in the chromosome regions, which do not contain diagnostic heterochromatin bands, it is not possible to identify rearrangements using C-banding. 1 Karyotypes of common wheat lines (F 10 ) with various introgressions of T. kiharae genetic material (С-banding). а – line 19, b – line 25–2, c – line 34–1, d – line 28 In the studied lines, C-banding did not reveal the introgression of a T. kiharae D-genome genetic material into the genome of common wheat varieties. The transfer of the T. kiharae G-genome genetic material was carried out mainly by means of translocations with breakpoints in interstitial chromosome regions that were formed between the corresponding homoeologous G- and the orthologous to it B-genome. kiharae chromatin in the form of a chromosome arm or large chromosome segments, C-banding revealed the formation of an intergenomic chromosome substitution: in the karyotypes of line 28, a pair of 2G chromosomes substituted a pair of 2B chromosomes (Fig. 1 d). A high frequency of the similar substitution in offsprings obtained from the crossing of common wheat varieties with T. kiharae and T. timopheevii was noted earlier by a number of authors [ 5 , 7 , 12 , 13 ]. Using C-banding, structural changes were detected only in the chromosome 2A of line 19. The presence of rearrangements in other chromosomes of A genome was not established due to the small number of diagnostic heterochromatin blocks in chromosomes A t of T. kiharae , which was also shown earlier by Badaeva et al. [ 5 , 13 ]. Amplification of PCR fragments specific to T. kiharae was detected using SSR markers localized in the short arm of chromosome 3B (lines 19 and 25–2). Single introgressions in chromosomes 2BL, 6BS and 7BL were found only in lines 28, 19 and 34–1, respectively (Table 1 ). In lines 19 and 20–1, only two SSR markers of the telomeric 5BL region amplified a fragment typical of T. kiharae (Fig. 2 ), which indicates the presence of short alien fragments and inability to identify them by C-banding. For lines with large T. kiharae chromatin introgression (25–2 and 34–1), microsatellite analysis data coincide with C-banding results. Microsporogenesis Study of meiosis in pollen mother cells (PMC) has shown the high cytological stability of F 10 lines. At metaphase I, the average number of univalents