Description:
<jats:p>Most pericentromeric regions of eukaryotic chromosomes are heterochromatic and are the most rapidly evolving regions of complex genomes. The closely related genomes within hexaploid wheat ( Triticum aestivum L., 2n = 6x = 42, AABBDD), as well as in the related Triticeae taxa, share large conserved chromosome segments and provide a good model for the study of the evolution of pericentromeric regions. Here we report on the comparative analysis of pericentric inversions in the Triticeae, including Triticum aestivum, Aegilops speltoides , Ae. longissima, Ae. searsii, Hordeum vulgare , Secale cereale , and Agropyron elongatum . Previously, 4 pericentric inversions were identified in the hexaploid wheat cultivar ‘Chinese Spring’ (‘CS’) involving chromosomes 2B, 4A, 4B, and 5A. In the present study, 2 additional pericentric inversions were detected in chromosomes 3B and 6B of ‘CS’ wheat. Only the 3B inversion pre-existed in chromosome 3S, 3S<jats:sup>l</jats:sup>, and 3S<jats:sup>s</jats:sup>of Aegilops species of the Sitopsis section, the remaining inversions occurring after wheat polyploidization. The translocation T2BS/6BS previously reported in ‘CS’ was detected in the hexaploid variety ‘Wichita’ but not in other species of the Triticeae. It appears that the B genome is more prone to genome rearrangements than are the A and D genomes. Five different pericentric inversions were detected in rye chromosomes 3R and 4R, 4S<jats:sup>l</jats:sup>of Ae. longissima, 4H of barley, and 6E of Ag. elongatum. This indicates that pericentric regions in the Triticeae, especially those of group 4 chromosomes, are undergoing rapid and recurrent rearrangements.</jats:p>