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Based on a C-banded chromosome analysis of Triticum aestivum x T. timopheevii hybrid lines, we developed a classification of the A(t) and G genome chromosomes that agrees with the standard genetic nomenclature of T. aestivum chromosomes. Transfer of genetic material from T. timopheevii to T. aestivum involved complete chromosomes, chromosome arms, or segments. Frequencies of chromosome substitution were highest for homoeologous group 2 and lowest for group 4. Moreover, B(G) substitutions were frequent compared to A(A(t)). The pattern of chromosome substitutions and rearrangements were unequal and depended on the genotype of the parental T. aestivum cultivar.

Triticum timopheevii and related species T. militinae (2n=28, A(t)G) and T. zhukovskyi (2n=42, A(m)A(t)G), hybrids T. kiharae, T. miguschovae, the amphidiploid T. timopheevii x T. tauschii (all 2n=42, A(t)GD), T. fungicidum (ABA(t)G) and T. timonovum (2n=56, A(t)A(t)GG) were analyzed using the C-banding technique. Chromosomes of the A(m) and A(t) genomes in the karyotype of T. zhukovskyi differed in their C-banding pattern. Partial substitutions of A(t)-genome chromosomes and a complete substitution of the G-genome chromosomes by homoeologous chromosomes of an unidentified tetraploid wheat species with an AB genome composition were found in the T. timonovum karyotype. A(t)- and G-genome chromosomes in the karyotypes of all studied species had similar C-banding patterns and were characterized by a low level of polymorphism. The comparative stability of the A(t) and G genomes is determined by the origin and specifity of cultivation of studied species.

Hexaploid triticales were crossed with common wheats, and the resultant froms were selected for either triticale (AD 213/5-80) or common wheat (lines 381/80, 391/80, 393/80). The cytogenetic analysis showed that all forms differ in their chromosome composition. Triticale AD 213/5-80 and wheat line 381/80 were stable forms with 2n = 6x = 42. Lines 391/80 and 393/80 were cytologically unstable. In triticale AD 213/5-80, a 2R (2D) chromosome substitution was found. Each of the three wheat lines had a chromosome formed by the translocation of the short arm of IR into the long arm of the IB chromosome. In line 381/80, this chromosome seems to be inherited from the 'Kavkaz' wheat variety. In lines 391/80 and 393/80, this chromosome apparently formed de novo since the parent forms did not have it. The karyotype of line 381/80 was found to contain rye chromosomes 4R/7R, 5R and 7R/4R. About 15% of the cells in line 391/80 contained an isochromosome for the 5R short arm and also a chromosome which arose from the translocation of the long arms of the 5D and 5R chromosomes. About one-third of the cells in the common wheat line 393/80 contained the 5R chromosome. This chromosome was normal or rearranged. Practical applications of the C-banding technique in the breeding of triticale is discussed.