*2.4. Other Aegilops Species*

Exploration of the chromosome structure in other *Aegilops* species has been based on genetic mapping and, in some instance, on physical mapping of low copy DNA sequences. Construction of a linkage map in *Ae. umbellulata* (UU), which was based on RFLP loci previously mapped in bread wheat, revealed that multiple chromosome rearrangements occurred in the evolution of this species. The U genome underwent a minimum of 11 reciprocal translocations and inversions to arrive at its current structure [75]. Additional possible rearrangements involving chromosomes 2U, 5U and 6U were supported by macrosyntenic comparisons of wheat and *Ae. umbellulata* chromosomes based on the chromosomal assignment of Conserved Orthologous Set (COS) markers in both species [76].

The M genome of *Ae. comosa* underwent some rearrangements relative to wheat. Chromosome 2M carries some genetic material from 5M, and a segmen<sup>t</sup> from 7M is present on 3M [76]. However, the M genome poses a chromosome structure more similar to that of wheat than the U genome.

A FISH map of 121 cDNA probes, with an average of 18 markers per chromosome, revealed the presence of evolutionary rearrangements in *Ae. markgrafii* (syn. *Ae. caudata*, genome CC) [77]. Chromosomes 1C and 5C are collinear to wheat chromosomes 1D and 5D. The other five chromosomes are highly rearranged. The density of markers per chromosome arm made possible to determine the positions of at least 19 breakpoints, which flanked adjacent rearranged chromosome segments with preserved synteny. Rearrangements consisted of pericentric inversions (chromosomes 2C, 3C, 4C and 6C), intra-chromosomal translocations (2C, 3C, 6C and 7C) and inter-chromosomal translocations between 2C-4C, 3C-4C and 6C-7C. In addition, one duplicated segmen<sup>t</sup> was found on chromosomes 6C and 7C, and three deletions on chromosomes 4C and 6C.
