Arm homoeology of wheat and rye chromosomes

Abstract

Meiotic pairing was studied at metaphase I in three different cv. Chinese Spring × rye hybrid combinations (5B deficient, 3D deficient, and normal ABDR) to establish the arm homoeology of wheat and rye chromosomes. The majority of individual wheat chromosomes and their arms, as well as the arms of chromosomes 1R and 5R, were identified by means of C-banding. The results on pairing relationships support the genome reallocation of chromosomes 4A and 4B. The short arms of wheat chromosomes belonging to homoeologous groups 1, 3, 5, and 6 and of chromosome pairs 4A–4D and 7A–7D showed full pairing homoeology as well as the long arms of wheat chromosomes of groups 1, 3, 6, and 7 and of chromosome pairs 4A–4D and 5B–5D. Chromosomes 2A, 2B, and 2D were homoeologous, but the homoeologies of their arms were not identified. Reduced homoeologies of the 4BL arm to 7AS and 7DS, of the 5AL arm to 4AL and 4DL, and of the 7BS arm to 5BL and 5DL were identified. Arms 4BL, 5AL, and 7BS are involved in a double translocation that arose during the evolution of common wheat. The homoeology relationships of chromosome arm 4BS were not identified since this arm seldom paired. The homoeologous pairing pattern between wheat chromosomes was characterized by a remarkable predominance of A–D associations, altered only by structural changes in groups 4 and 5. Chromosome arm 1RL showed full pairing homoeology to 1AL, 1BL, and 1DL, while 5RL was homoeologous to 5AL and partially homoeologous to 4AL and 4DL. It is concluded that 5RL carries a translocated segment from 4RL. Key words: homoeologous pairing, translocations, wheat evolution, C-banding.

Single-copy gene fluorescence in situ hybridization and genome analysis: Acc-2 loci mark evolutionary chromosomal rearrangements in wheat

“…Chromosome 4A of T. monococcum, T. turgidum, and bread wheat is known to have a rearranged structure that resulted from a 4AL/5AL translocation, which occurred at the diploid level. Further rearrangements involving chromosome arms 7BS, a paracentric and two pericentric inversions, took place at the tetraploid level (Naranjo et al 1987;Devos et al 1995;Mickelson-Young et al 1995;Miftahudin et al 2004). Our results confirm the presence of the A-genome-specific translocation T4AL/5AL that is shared by several related species and is also present in the derived A genomes of allopolyploid species Rodriguez et al 2000) (Fig.…”

Gene evolution at the ends of wheat chromosomes

“…Nonterminal regions of NSH EST concentration along the chromosome length might be explained by recombination hot spots (41). Increased frequency in the nonterminal 4AL5 deletion bin could be explained by the 4A, 5A, 7B cyclic translocation (42,43) that moved the 5AL terminal segment to this site.…”

Comparative Genomics of Plant Chromosomes

“…Pioneering efforts in the comparative mapping of maize and sorghum (Hulbert et al, 1990) have been supported by more detailed studies (Whitkus et al, 1992;Berhan et al, 1993;Binelli et al, 1993;Chittenden et al, 1994;Pereira et al, 1994) and supplemented by the comparative organization of maize and rice , wheat and rice (Kurata et al, 1994), and maize, wheat, and rice . A host of investigations additionally encompasses many other cultivated Poaceae, with particular emphasis on the interrelationships among the homeologous chromosome sets of the Triticeae and their relatives (see Naranjo et al, 1987;Chao et al, 1989;Liu and Tsunewaki, 1991;Devos et al, 1992aDevos et al, , 1992bDevos et al, , 1993Devos et al, , 1995Liu et al, 1992;Xie et al, 1993;Namuth et al, 1994;Hohmann et al, 1995;Marino et al, 1996;Mickelson-Young et al, 1995;Nelson et al, 1995aNelson et al, , 1995bNelson et al, , 1995cVan Deynze et al, 1995). Curiously, even in the relatively "conservative" Poaceae, certain lineages appear to be rapidly evolving.…”