A Set of Cytogenetic Markers Allows the Precise Identification of All A-Genome Chromosomes in Diploid and Polyploid Wheat

Karyotypes of 3 diploid wheat species containing different variants of the A-genome, Triticum boeoticum (A b ), T. monococcum (A b ), and T. urartu (A u ), were examined using C-banding and FISH with DNA probes representing 5S and 45S rDNA families, the microsatellite sequences GAA n and GTT n , the already known satellite sequences pSc119.2, Spelt52, Fat , pAs1, and pTa535, and a newly identified repeat called Aesp_SAT86. The C-banding patterns of the 3 species in general were similar; differences were observed in chromosomes 4A and 6A. Besides 2 major 45S rDNA loci on chromosomes 1A and 5A, 2 minor polymorphic NORs were observed in the terminal part of 5AL and in the distal part of 6AS in all species. An additional minor locus was found in the distal part of 7A b L of T. boeoticum and T. monococcum, but not in T. urartu. Two 5S rDNA loci were observed in 1AS and 5AS.