The work is dedicated to solving the question if alien chromatin inclusions (introgressions) to a stable consolidated genome can cause (epi)genetic changes in the resident genome. The research was performed on common wheat introgressive lines, derived from the cross of common wheat cultivar Aurora Triticum aestivum (AABBDD) (♂) with wheat-Aegilops artificially developed genome substituted amphidiploids with genome structure AABBXX. In amphidiploids AABB is tetraploid component of Aurora genome, and XX subgenome is a genome of species Aegilops speltoides (SS) in Aurodes, Ae. sharonensis (SshSsh) in Aurosis, and Ae. umbellulata (UU) in Aurolata. The lines were developed and characterized for homeological identity of their introgressions of different amount and quality in the 90’s. During some time of observation, it became obvious that beside stable lines, that demonstrated the same characteristics from generation to generation, there were also lines that were permanently changing for one or several traits, while remaining 42-chromosome. The assumption was made that their phenotypic instability was correlated with processes occurring in their genomes, and which were triggered by the hybrid nature of the genomes. Introgressive lines, both stable and variable, were studied for their karyotypes, and no difference among two groups of lines was identified. The lines were studied using biochemical (genes of storage proteins and enzymes), morphological (presence/absence of awns, mature glume color, spike shape, glume rigidity, pit on the glume base, glume hairiness) traits, and spectra of PCR products obtained with primers to transposons and SSR loci, specific to chromosomes of particular homeological group or chromosome specific. Comparative study of electrophoretic spectra of proteins and PCR products has shown that variability observed in generations of amphidiploids and introgressive lines is an integral feature of wheat plants with genomes of hybrid origin, and (epi)genetic changes occurring in hybrid genomes are the basis of this variability. This was demonstrated on two models: changes in gliadin spectra of introgressive lines and beta-amylase spectra are accompanied by changes in nucleotide sequences of genes. These changes can be caused by transposon activity, which can be localized directly in the gene (β-Amy), or in the intergenic region (Gli); and also by expansion of microsatellite repeats coding Glutamine (Gli). The main question of this research is: what is the real cause of this burst of variability observed in progenies of hybrid genomes: the presence of alien chromatin in their genomes, which is directly involved in the control of traits that we consider introgressed, or whether the changes arise in the chromatin of the resident genome. This question should be answered in favor of the latter assumption. Stability of the resident genome is disturbed by the molecular processes, which are triggered by the bringing together of different constant consolidated genomes in one hybrid genome. This mechanism of variability increase in introgressive progeny has great potential, as variability of plants of introgressive origin goes beyond the limits defined by the output genomes.
Genetic analysis of introgressive lines for the trait of leaf sheath edge hairiness, presence awns, mature glume color, and powdery mildew resistance, led to the determination of genetic control of these traits in introgressive lines with alien genes, and identification of new genes: Hs-Ssh, Awn1, Bg2, introduced to the genomes of wheat lines from Aegilops species. The main result of this part of the research is the opinion that genetic analysis of introgressive lines does not give adequate results without careful study of cross components as to their genome structures, and hybrids of different populations – regarding features of transmission of the studied traits to their progeny in connection with this structure. For modeling of patterns of inheritance in terms of ratios of volumes of phenotypic classes, it is very important to have information about possibilities of formation of aneuploid gametes with reduced functionality and zygotes with limited viability, variability of progeny viability in segregating populations on different stages of ontogenesis. This information can be obtained through interpretation of chromosome configurations in M1 PMC of F1 hybrid. Development of an adequate model of inheritance requires performance of diallel crossings, and their results will serve to cross-check the model’s accuracy.
