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 pos sible 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 deter mined 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.

Although the wheat A genomes have been intensively studied over past decades, many questions concerning the mechanisms of their divergence and evolution still remain unsolved. In the present study we performed comparative analysis of the A genome chromosomes in diploid (Triticum urartu Tumanian ex Gandilyan, 1972, Triticum boeoticum Boissier, 1874 and Triticum monococcum Linnaeus, 1753) and polyploid wheat species representing two evolutionary lineages, Timopheevi (Triticum timopheevii (Zhukovsky) Zhukovsky, 1934 and Triticum zhukovskyi Menabde & Ericzjan, 1960) and Emmer (Triticum dicoccoides (Körnicke ex Ascherson & Graebner) Schweinfurth, 1908, Triticum durum Desfontaines, 1798, and Triticum aestivum Linnaeus, 1753) using a new cytogenetic marker – the pTm30 probe cloned from Triticum monococcum genome and containing (GAA)56 microsatellite sequence. Up to four pTm30 sites located on 1AS, 5AS, 2AS, and 4AL chromosomes have been revealed in the wild diploid species, although most accessions contained one–two (GAA)n sites. The domesticated diploid species Triticum monococcum differs from the wild diploid species by almost complete lack of polymorphism in the distribution of (GAA)n site. Only one (GAA)n site in the 4AL chromosome has been found in Triticum monococcum. Among three wild emmer (Triticum dicoccoides) accessions we detected 4 conserved and 9 polymorphic (GAA)n sites in the A genome. The (GAA)n loci on chromosomes 2AS, 4AL, and 5AL found in of Triticum dicoccoides were retained in Triticum durum and Triticum aestivum. In species of the Timopheevi lineage, the only one, large (GAA)n site has been detected in the short arm of 6At chromosome. (GAA)n site observed in Triticum monococcum are undetectable in the Ab genome of Triticum zhukovskyi, this site could be eliminated over the course of amphiploidization, while the species was established. We also demonstrated that changes in the distribution of (GAA)n sequence on the A-genome chromosomes of diploid and polyploid wheats are associated with chromosomal rearrangements/ modifications, involving mainly the NOR (nucleolus organizer region)-bearing chromosomes, that took place during the evolution of wild and domesticated species.

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