We studied C-band polymorphism in seven representative Ethiopian tetraploid (2n=4x=28) wheat (Triticum turgidum L.) landrace morphotypes (=genotypes), and attempted to localize chromosomal breakpoints in five of them that are known to carry one reciprocal translocation each, relative to the variety Senatore Cappelli (SC). No difference for chromosomal arm-ratios was observed except that 7B was inconsistent. All chromosomes showed different levels of C-banding variation except 1A and 4A. No two morphotypes were identical. However, the variation was not associated with spike morphology or collection locality. None of the morphotypes showed a similar C-banding pattern to SC for chromosome arms 3BL, 5AL and 5BL. Unusual bands and banding patterns were observed on chromosome arms 2AS, 7AL and 5BL. Chromosome 7B in one of the morphotypes (B-3-11) was conspicuously different. The landrace variety, M-04-118, might have carried a 2B/4B translocation or a terminal deletion on 2BS. Generally, unequivocal localization of translocation breakpoints by C-banding alone proved difficult. Nevertheless, it is plausible that most of the translocations in these landraces have non-centromeric breakpoints. Structural rearrangements within the AB genome alone do not account for the observed C-banding variation, therefore, other possibilities such as "multiple lineage" and/or D genome introgression may need to be pursued.

Key words: Triticum turgidum, Wheat, Karyotype, C-banding polymorphism, Chromosomal rearrangements


Introduction

Wheat (Triticum spp.) consists of diploid (2n=2x=14), tetraploid (2n=4x=28) and hexaploid (2n=6x=42) species. The tetraploids (T. turgidum L.) and hexaploids (T. aestivum L. em. Thell.) share two genomes (AB) in common. Intervarietal C-band polymorphism, is well documented in the diploid progenitors and near relatives (Friebe and Gill 1996), in the wild tetraploid wheat, T. araraticum Jakubz. (A^t G) (Badaeva, Badaev et al. 1994), and hexaploid wheat (ABD) (Friebe and Gill 1994). However, there is no comparable study in the cultivated tetraploid forms (AB genomes) except that of Landgeva et al. (1995) who reported the N-banding patterns of four varieties.

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