Overall, 253 genomic wheat (Triticum aestivum) microsatellite markers were studied for their transferability to the diploid species Aegilops speltoides, Aegilops longissima, and Aegilops searsii, representing the S genome. In total, 88% of all the analyzed primer pairs of markers derived from the B genome of hexaploid wheat amplified DNA fragments in the genomes of the studied species. The transferability of simple sequence repeat (SSR) markers of the T. aestivum A and D genomes totaled 74%. Triticum aestivum – Ae. speltoides, T. aestivum – Ae. longissima, and T. aestivum – Ae. searsii chromosome addition lines allowed us to determine the chromosomal localizations of 103 microsatellite markers in the Aegilops genomes. The majority of them were localized to homoeologous chromosomes in the genome of Aegilops. Several instances of nonhomoeologous localization of T. aestivum SSR markers in the Aegilops genome were considered to be either amplification of other loci or putative translocations. The results of microsatellite analysis were used to study phylogenetic relationships among the 3 species of the Sitopsis section (Ae. speltoides, Ae. longissima, and Ae. searsii) and T. aestivum. The dendrogram obtained generally reflects the current views on phylogenetic relationships among these species.Key words:Triticum aestivum, Aegilops speltoides, Aegilops longissima, Aegilops searsii, microsatellite, SSR, chromosome addition lines, phylogeny.
Telomeric and subtelomeric regions are essential for genome stability and regular chromosome replication. In this work, we have characterized the wheat BAC (bacterial artificial chromosome) clones containing Spelt1 and Spelt52 sequences, which belong to the subtelomeric repeats of the B/G genomes of wheats and Aegilops species from the section Sitopsis.
Transposable elements (TEs) are a rapidly evolving fraction of the eukaryotic genomes and the main contributors to genome plasticity and divergence. Recently, occupation of the A- and D-genomes of allopolyploid wheat by specific TE families was demonstrated. Here, we investigated the impact of the well-represented family of gypsy LTR-retrotransposons, Fatima, on B-genome divergence of allopolyploid wheat using the fluorescent in situ hybridisation (FISH) method and phylogenetic analysis.
Genotyping was performed for the leaf rust-resistant line 73/00i (Triticum aestivum × Aegilops speltoides). Fluorescence in situ hybridization (FISH) with probes Spelt1 and pSc119.2 in combination with microsatellite analysis were used to determine the locations and sizes of the Ae. speltoides genetic fragments integrated into the line genome. Translocations were identified in the long arms of chromosomes 5B and 6B and in the short arm of chromosome 1B. The Spelt1 and pSc119.2 molecular cytological markers made it possible to rapidly establish lines with single translocation in the long arms of chromosomes 5B and 6B. The line carrying the T5BS · 5BL-5SL translocation was highly resistant to leaf rust, and the lines carrying the T6BS · 6BL-6SL translocation displayed moderate resistance. The translocations differed in chromosomal location from known leaf resistance genes transferred into common wheat from Ae. speltoides. Hence, it was assumed that new genes were introduced into the common wheat genome from Ae. speltoides. The locus that determined high resistance to leaf rust and was transferred into the common wheat genome from the long arm of Ae. speltoides chromosome 5S by the T5BS · 5BL-5SL translocation was preliminarily designated as LrAsp5.
Enrichment of grains with anthocyanins is considered a feasible approach to improving the nutritional properties of bread wheat. Here, two black-grained substitution lines with either 4B or 4D chromosomes substituted by wheatgrass (Thinopyrum ponticum) 4Th were created via marker-assisted combining the anthocyanin biosynthesis regulatory genes Pp-1, Pp3 (Purple pericarp), and Ba1 (Blue aleurone) in the genetics background of cv. Saratovskaya 29. The black grains manifested the simultaneous accumulation of anthocyanins in aleurone, and the pericarp layers resulted in the highest total anthocyanin content (TAC), which amounted to approximately the sum of TACs of the purple and blue grains. The lines with substitution 4Th(4B) had long trichomes on the leaves, whereas the lines with substitution 4Th(4D) did not differ from parental cv. Saratovskaya 29. Despite the chromosome substitution having a positive effect on the main spike length, the other yield-related traits (grain weight per main spike, the spike number per plant, and the 1000-grain weight) were decreased in the lines with chromosome substitution. The developed lines together with the parental ones constitute a valuable model for comparative studies and genetic stock for breeding commercial wheat cultivars featuring high levels of anthocyanins in grains.
This review is devoted to the introgressive hybridization of common wheat, the process of integrating the genes of other cultivated or wild species from the secondary and tertiary gene pools into its genome in order to increase the genetic diversity of this most important agricultural crop. The results achieved in the introgressive hybridization of common wheat over the past 20 years are summarized, the distribution of alien translocations by subgenomes and chromosomes of common wheat is analyzed, and the possibilities for further development of this direction of research and selection based on the use of alien genetic material are discussed.