*2.6. Barley*

The first analysis of the barley chromosome structure relative to wheat was based on the compared positions of over 100 RFLP loci in the linkage maps of *T. monococcum* and barley [81]. The synteny of the A m and H genomes was shown to be highly conserved. They di ffer in the translocation T(4AL-5AL) present in *T. monococcum* and in two paracentric inversions that involve the long arm of group 1 and 4 chromosomes. A further reported genetic map constructed using 242 EST and 96 RFLP markers from barley confirmed structural di fferences detected between the long arms of group 4 and 5 chromosomes [82]. Assembly of 21,766 genes in a linear order and its comparison with high-density physical maps of the wheat A, B and D genomes, showed macro-synteny perturbation because of translocations involving chromosome arms 4AL, 5AL and 7BS, pericentric inversions produced in chromosomes 4A, 5A, 2B and 3B, and the absence of some homoeologous segments in chromosome arms 1AS, 1AL, 2AL, 2DL, 5AL, 5BL and 5DL [83]. In addition, a pericentric inversion was assumed to have occurred in chromosome 1H after divergence of the barley lineage. A high-quality reference genome assembly for barley was later reported [84].
