Repeated sequence DNA comparisons between Triticum and Aegilops species

Abstract

The families of repeated sequences in the genomes of a range of Triticum and Aegilops species have been compared. All the genomes are very similar. However, using a DNA probe from Aegilops speltoides that contains the most highly repeated sequences, diploid Aegilops species could be distinguished from diploid Triticum species. Different Aegilops species' DNAs also hybridise to differing extents with this probe. The results are consistent with the hypothesis that speciation is accompanied by quantitative changes in the repeated sequence complements of genomes. Most if not all of the families of repeated sequences in hexaploid wheat can be detected in Aegilops speltoides (related to the B genome) and in Aegilops squarrosa (related to the D genome). However, some families of repeated sequences of hexaploid wheat were not found in Triticum monococcum (related to the A genome). Some of the most highly repeated sequences of hexaploid wheat are preferentially concentrated in the B genome. These sequences are useful as probes for distinguishing the three diploid genomes of hexaploid wheat.