Wild relatives of bread wheat are potential sources of valuable genetic materials for wheatimprovement. Karyotype analysis plays an important role in the identification and designation ofchromosomes in many plant species. In this study, the karyotype features and nucleolar organizer regions(NORs) of 21 wheat genotypes representing diploid, tetraploid and hexaploid species and belonging towild, cultivated and synthetic groups were investigated. Total chromosome length (TCL) values varyacross the genotypes. The highest value (99.1 µm) was recorded in one of a synthetic hexaploid wheat(Doy1/ Ae. squarrosa (458)) with a mean chromosome length (MCL) of 5.67±0.59 µm, while the lowestvalue (39.48µm) was found in T. monococcum species with a mean chromosome length (MCL) of4.06±0.51 µm. Cluster analysis based on chromosomal characteristics and karyotype asymmetry indicesincluding symmetry index (S %), total form percentage (TF %), Romero-Zarco's indices (A1and A2) andStebbin's classification divided the genotypes into three groups. Results revealed that group 1, includingsynthetic hexaploid wheat accessions, had the most asymmetric karyotype in terms of centromere positionand chromosome length. Ag-NOR banding identified two nucleolus organizer regions (NORs) on the longarms of the chromosomes 1B and 6B in both tetraploid and hexaploid wheats.
Key words: Wild relatives, synthetic wheat, chromosome, karyotype, nucleolus organizer regions.